Evaluation of cerebrospinal fluid Human Epididymis Protein 4 for leptomeningeal metastasis in Non-Small Cell Lung Cancer: A retrospective cohort study

Evaluation of cerebrospinal fluid Human Epididymis Protein 4 for leptomeningeal metastasis in Non-Small Cell Lung Cancer: A retrospective cohort study | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Evaluation of cerebrospinal fluid Human Epididymis Protein 4 for leptomeningeal metastasis in Non-Small Cell Lung Cancer: A retrospective cohort study Yongjuan Lin, Mingyang He, Yu Xie, Zhenyu Yin, Xiawen Lin, Lingli Hu This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8736012/v1 This work is licensed under a CC BY 4.0 License Status: Under Revision Version 1 posted 11 You are reading this latest preprint version Abstract Background : Diagnosing and monitoring leptomeningeal metastasis presents a significant clinical challenge. This study evaluated cerebrospinal fluid (CSF) Human Epididymis Protein 4 (HE4) as a novel diagnostic and monitoring biomarker for leptomeningeal metastasis in non-small cell lung cancer. Methods : A prospective cohort study enrolled 117 participants (including 61 non-small cell lung cancer patients with leptomeningeal metastasis and 56 controls without central nervous systemmalignancies) from March 2023 to December 2024. Paired CSF and serum levels of HE4, carcinoembryonic antigen (CEA), and CYFRA21-1 were measured using electrochemiluminescence immunoassay. Diagnostic performance was assessed using receiver operating characteristic (ROC) curve analysis. Serial monitoring was also performed in a subset of patients. Results : CSF HE4 levels were significantly higher in leptomeningeal metastasis patients compared to controls (median 807.00 vs. 99.35 pmol/L, P < 0.001) and markedly exceeded paired serum levels, indicating a distinct CSF-serum gradient. For leptomeningeal metastasis diagnosis, CSF HE4 (AUC = 0.895) demonstrated superior performance to CSF CEA and CYFRA21-1. At an optimal cutoff of 173.00 pmol/L, the sensitivity and specificity were 83.21% and 92.86%, respectively. Subgroup analysis revealed significantly higher CSF HE4 levels in patients with positive CSF cytology, particularly those with progressive disease. Serial monitoring demonstrated that dynamic changes in CSF HE4 levels correlated with treatment response during intrathecal chemotherapy. Conclusion : CSF HE4 is a promising biomarker for the diagnosis of non-small cell lung cancer related leptomeningeal metastasis. For CSF HE4, its robust diagnostic performance and correlation with disease activity support its use for both initial diagnosis and therapeutic monitoring. Leptomeningeal metastasis Non-small cell lung cancer Cerebrospinal fluid Human epididymis protein 4 Biomarker Diagnosis Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 1. Background Leptomeningeal metastasis (LM) is a severe complication of non-small cell lung cancer (NSCLC), affecting 3-5% of patients with advanced disease and resulting in a poor prognosis[1,2]. Its diagnosis remains difficult, as cerebrospinal fluid (CSF) cytology has a low initial sensitivity (~50%), and magnetic resonance imaging (MRI) is non-diagnostic in a significant proportion of cases[3,4]. This highlights an urgent need for reliable CSF biomarkers to enhance LM detection. Human epididymis protein 4 (HE4), a secretory protein overexpressed in lung cancer, has emerged as a promising candidate. Beyond its established role in diagnosis, HE4 is increasingly recognized as a critical tool for dynamic disease monitoring and prognostic stratification across various malignancies[5,6]. In high-grade serous ovarian carcinoma, baseline serum HE4 levels correlate more strongly with surgical tumor burden than cancer antigen 125 (CA125) , providing a more accurate initial assessment of disease extent[7]. Notably, longitudinal monitoring shows that HE4 levels during primary therapy are a significant predictor of platinum-resistant relapse, while serum HE4 concentration at first recurrence serves as an independent prognostic factor for overall survival[8]. This prognostic value is further refined in the context of modern targeted therapies. For instance, during poly ADP-ribose polymerase (PARP) inhibitor maintenance treatment for epithelial ovarian cancer, serial HE4 measurement (using a ≥25% increase threshold) demonstrates significantly higher accuracy than CA125 in detecting disease progression, highlighting its superior reliability in this novel therapeutic setting[9]. The translational utility of HE4 dynamic monitoring is also evident in lung adenocarcinoma, where combining HE4 with CYFRA21-1 in post-resection surveillance improves recurrence detection, outperforming either marker alone[10]. Taken together, serial HE4 assessment offers a powerful, integrative approach for evaluating real-time tumor dynamics, predicting therapeutic resistance, and detecting early recurrence, thereby supporting a more proactive and personalized cancer management strategy. A recent landmark study by Li et al. established the diagnostic value of CSF HE4 for LM in lung adenocarcinoma, demonstrating its superior performance and synergistic effect when combined with carcinoembryonic antigen related cell adhesion molecule 6 (CEACAM6) [11]. These promising findings positioned CSF HE4 as a potent diagnostic biomarker. Notably, the study of Li et al. exclusively enrolled patients with cytologically positive CSF, which inherently confirms LM diagnosis[11]. To comprehensively assess the biomarker’s performance in a more representative clinical spectrum, our study included both CSF cytology-positive and cytology-negative patients. However, despite these advances, current evidence on the application of CSF HE4 for monitoring treatment response and predicting progression in LM remains limited. Thus, our study aimed to validate the diagnostic accuracy of CSF HE4 in an independent cohort and, more importantly, to explore its potential for serial therapeutic monitoring, addressing one of the key unresolved clinical challenges in LM management. 2. Materials and methods 2.1. Ethical approval A prospective cohort study was conducted using data from the Department of Geriatric Oncology at XX Hospital, a tertiary comprehensive hospital (hospital information is concealed for peer review). The study received approval from the Ethics Committee of XX Hospital (No. 2024-544-02; hospital information is concealed for peer review). Informed consent was obtained from the family members of all patients, and all procedures adhered to the ethical principles outlined in the Declaration of Helsinki. 2.2. Patients Between March 2023 and December 2024, 61 consecutive NSCLC patients with a confirmed diagnosis of LM were enrolled. The LM diagnosis followed the European Association of Neuro-Oncology (EANO)-ESMO criteria[12]. Inclusion criteria were: 1) patients aged 18 years or older; 2) a confirmed pathological diagnosis of NSCLC; 3) LM diagnosis based on positive CSF cytology or, in the absence of cytology, the presence of typical neurological symptoms/signs combined with characteristic MRI findings. Exclusion criteria included: 1) a history of encephalitis, significant craniocerebral trauma, neurosurgical intervention, or cerebral radiotherapy within the previous six months; 2) concurrent active malignancies; 3) incomplete clinical data or insufficient biological samples for study analysis. Fig.1 shows the recruitment flowchart of NSCLC patients with LM. Control subjects were selected from patients presenting with other neurological conditions (e.g., cognitive impairment, benign intracranial tumors, meningitis) during the same study period. Control participants were required to have undergone lumbar puncture yielding sufficient CSF volume, with paired serum samples collected on the same day. Individuals with evidence of central nervous system malignancy or current metastatic disease were excluded. 2.3. Clinical data collection Lumbar puncture was performed as the standard initial diagnostic procedure to confirm LM in all suspected cases. Patients were transferred to the procedure room, where an assistant prepared the necessary equipment and assisted with positioning. Lumbar puncture was performed under aseptic conditions, and CSF flow confirmation was followed by measurement of opening pressure. Approximately 6-8 mL of CSF was collected for laboratory analysis, including cytological examination, HE4 measurement, tumor marker assessment, and circulating tumor cell detection. After needle removal, the puncture site was disinfected and covered with a sterile dressing. Patients were instructed to remain supine, without a pillow, for six hours following the procedure. Paired CSF and peripheral blood samples were collected during intrathecal chemotherapy for dynamic HE4 monitoring. These samples were analyzed using previously described methods. The initial lumbar puncture in LM patients was used to establish a cytological diagnosis and obtain baseline measurements of HE4 and other tumor markers. Subsequent lumbar punctures or Ommaya reservoir accesses for intrathecal drug administration followed the same protocol, with CSF sampled prior to each chemotherapy cycle for HE4 and biomarker assessments. Clinical and demographic data, including age, sex, Karnofsky Performance Status (KPS), intracranial pressure (ICP), CSF routine parameters (white blood cell count, protein, glucose, chloride), and MRI findings, were extracted from electronic medical records. 2.4. Laboratory measurement of biomarkers CSF and blood samples were centrifuged at 3000 rpm for 5 minutes to isolate the supernatant CSF and serum for analysis. The specimens were stored at room temperature for no more than 5 hours, or at 2–8°C for up to 2 days. Alternatively, they could be stored at -20 to -70°C for up to 12 weeks. HE4 and CYFRA21-1 concentrations were measured using the Roche cobas e801 electrochemiluminescence immunoassay system (Roche Diagnostics GmbH, Mannheim, Germany), while carcinoembryonic antigen ( CEA) was assessed using the Siemens Atellica Solution chemiluminescence immunoassay analyzer (Siemens Healthcare Diagnostics Inc., New York, USA). All assays were conducted using instrument-specific reagent kits and calibrators, with the following lot numbers: HE4 reagent Lot: 84899001, HE4 calibrator Lot: 768265; CYFRA21-1 reagent Lot: 81414301, CYFRA21-1 calibrator Lot: 794449; CEA reagent Lot: 69175223, CEA calibrator Lot: CAL D57940A20. Bio-Rad tumor marker control sets (Levels 547, Lot: 94991, and 549, Lot: 94993) were used for quality control. Testing was conducted in strict accordance with the standard operating procedures (SOP) for both reagents and instruments. All measurements were performed by technicians blinded to the study hypothesis and the clinical group allocation of participants, with blinding maintained until all data were collected and locked for analysis. 2.5. Statistical Analysis Statistical analyses were performed using SPSS 25.0 (IBM Corp.) and GraphPad Prism 9.0. Continuous variables with non-normal distributions were expressed as medians and interquartile ranges (IQR) and compared using the Mann-Whitney U test or Kruskal-Wallis test. Categorical variables were compared using the Chi-square test or Fisher's exact test. Paired comparisons between CSF and serum levels were made using the Wilcoxon signed-rank test. Spearman's rank correlation coefficient was used to assess correlations. The diagnostic performance of biomarkers was evaluated through receiver operating characteristic (ROC) curve analysis, and the area under the curve (AUC) values were compared using the DeLong test. A two-sided P- value of < 0.05 was considered statistically significant. 3. Results 3.1. Patient Characteristics The clinical characteristics of the 61 LM patients and 56 controls are summarized in Table 1. No significant differences were observed between the two groups in terms of age, sex, or KPS. As expected, LM patients exhibited significantly higher ICP ( P = 0.003) and CSF protein levels ( P = 0.001), alongside lower CSF glucose levels ( P = 0.001) compared to controls. Table 1. The comparison of clinical characteristics between LM patients and control group. Group LM (n=61) Control (n=56) Z /X 2 value P value Male/Femal(n) 26/35 28/28 0.639 0.424 Age, Mean ± SEM (yr) 56.00 (53.00, 62.00) 56.00 (47.50, 66.50) 0.966 0.334 ICP 150.00 (120.00, 230.00) 130.00 (100.00, 155.00) 2.993 0.003 KPS 60.00 (50.00, 70.00) 60.00 (50.00, 70.00) -0.073 0.942 CSF WBC 5.00 (2.00, 8.00) 3.00 (2.00, 29.00) -0.167 0.867 CSF Lymphocyte 4.00 (2.00, 7.00) 3.00 (1.00, 19.50) -0.248 0.804 CSF Neutrophil 1.00 (0.00, 1.00) 1.00 (0.00, 3.00) 0.230 0.818 CSF Protein 563.70 (370.50, 885.50) 495.05 (337.45, 726.00) -3.258 0.001 CSF Glucose 2.92 (2.64, 3.42) 3.45 (2.94, 3.98) -3.277 0.001 CSF chloride 123.50 (119.40, 125.60) 125.50 (122.85, 127.25) 1.129 0.259 CSF HE4 (pmol/L) 807.00 (206.00, 1580.00) 99.35 (79.55, 124.50) 7.361 0.000 CSF CEA (U/ml) 11.28 (1.62, 71.21) 2.50 (1.50, 2.50) 3.803 0.000 CSF CYFRA21-1 (U/ml) 3.16 (1.30, 12.50) 1.63 (1.50, 1.74) 4.147 0.000 Serum HE4 (U/ml) 128.00 (98.10, 182.00) 61.05 (46.15, 75.65) 7.707 0.000 Serum CEA (U/ml) 30.81 (2.36, 76.08) 7.50 (1.89, 7.50) 3.945 0.000 Serum CYFRA21-1 (U/ml) 2.66 (1.93, 3.41) 1.76 (1.35, 2.33) 4.567 0.000 Abbreviations: CEA:carcinoembryonic antigen; CSF: cerebrospinal fluid; HE4: human epididymis protein 4; ICP: intracranial pressure; KPS: Karnofsky Performance Status; LM: leptomeningeal metastasis; SEM: standard error of the mean; WBC: white blood cell 3.2. Elevated CSF HE4 Levels in LM Patients CSF HE4 levels were markedly elevated in the LM group compared to controls [807.00 (206.00-1580.00) vs. 99.35 (79.55-124.50), Z = 7.361, P < 0.001; Fig. 2A]. Similarly, serum HE4 levels were higher in LM patients than in controls [128.00 (98.10-182.00) vs. 61.05 (46.15-75.65), Z = 7.707, P < 0.001; Fig. 2B]. Notably, in LM patients, CSF HE4 levels significantly exceeded those in the paired serum samples ( P < 0.001; Fig. 2C), with a weak but statistically significant correlation between the two compartments ( r = 0.376, P = 0.003; Fig. 2D). This CSF-serum gradient was not observed in the control group. 3.3. Diagnostic Performance of CSF Biomarkers ROC curve analysis was performed to evaluate the diagnostic performance of the three CSF biomarkers (Table 2, Fig. 3). CSF HE4 demonstrated excellent diagnostic accuracy, with an AUC of 0.895 (95% confidence intervals: 0.830-0.960). At an optimal cutoff value of 173.00 pmol/L, the sensitivity and specificity for diagnosing LM were 83.21% and 92.86%, respectively. In contrast, the diagnostic power of CSF CEA (AUC 0.701, sensitivity 63.96%, specificity 89.29% at 3.01 U/mL) and CSF CYFRA21-1 (AUC 0.664, sensitivity 73.77%, specificity 67.21% at 1.78 U/mL) was significantly lower ( P < 0.05 for both comparisons with HE4). Table 2. ROC curves for CSF HE4 level for differentiating LM patients from control group. 95% CIs Influence factor AUC Cut-off value Sensitivity Specificity P Lower limit Upper limit CSF HE4 (pmol/L) 0.895 173.00 83.21% 92.86% ＜0.0001 0.830 0.960 CSF CEA (U/ml) 0.701 3.01 63.96% 89.29% 0.0002 0.597 0.805 CSF CYFRA21-1 (U/ml) 0.664 1.78 73.77% 67.21% 0.0018 0.560 0.767 Abbreviations: AUC: area under the curve; CEA:carcinoembryonic antigen; CI:Confidence interval; CSF: cerebrospinal fluid; HE4: human epididymis protein 4; LM: leptomeningeal metastasis; ROC: receiver operating characteristic 3.4. Correlation of CSF HE4 with Other Parameters and Clinical Subgroups Spearman correlation analysis in LM patients revealed that CSF HE4 levels showed a weak positive correlation with CSF white blood cell count ( r = 0.385, P = 0.002), protein ( r = 0.354, P = 0.005) and IL6 ( r = 0.255, P = 0.048). Additionally, moderate positive correlations were observed with CSF CEA ( r = 0.412, P = 0.001) and CYFRA21-1 ( r = 0.623, P < 0.0001). In contrast, CSF HE4 showed a moderate negative correlation with CSF glucose levels ( r =−0.493, P < 0.0001). Fig 4 illustrates the details. Subgroup analyses assessed CSF HE4 levels under different clinical conditions (Table 3). No significant differences were observed based on the presence of concurrent brain metastases ( P = 0.318), specific MRI findings ( P = 0.253), or the duration of LM symptoms ( P = 0.658). However, CSF HE4 levels were significantly higher in patients with positive CSF cytology compared to those diagnosed clinically or radiographically with negative cytology [964.50 (320.50-1600.00) vs. 152.80 (77.80-214.00) pmol/L, P = 0.015]. Notably, patients with progressive disease (PD) had substantially higher CSF HE4 levels than those with non-PD [1189.00 (784.00-2120.00) vs. 352.50 (180.50-1162.50), P = 0.011]. Table 3. Comparison of CSF HE4, CEA, and CYFRA21-1 levels in different groups Cases (n=61) CSF HE4 CSF CEA CSF CYFRA21-1 P P P Accompanying brain metastasis 0.318 0.537 0.701 Yes 765.00 (239.00, 1171.50) 11.83 (1.83, 112.17) 3.79 (1.79, 11.85) No 990.00 (206.00, 2120.00) 9.72 (0.72, 65.26) 2.24 (1.24, 14.60) MRI finding at LM diagnosis 0.253 0.489 0.644 Yes 784.00 (206.00, 1384.00) 11.70 (1.70, 71.21) 3.30 (1.30, 11.20) No 1046.00 (278.00, 3444.00) 3.87 (0.87, 110.09) 4.44 (1.44, 18.95) Positive for CSF cytology 0.015 0.005 0.045 Yes 964.50 (320.50, 1600.00) 11.27 (2.27, 107.37) 3.72 (1.72, 13.55) No 152.80 (77.80, 214.00) 0.50 (0.50, 4.38) 1.73 (0.73, 1.92) Treatment approaches 0.053 0.457 0.165 Ommaya 295.50 (180.50, 485.00) 5.45 (1.45, 28.00) 1.10 (1.10, 3.02) Lumbar puncture 972.00 (214.00, 1630.00) 11.62 (1.62, 72.21) 3.58 (1.58, 17.50) LM symtoms to diagnosis 0.658 0.482 0.447 ＜6m 893.50 (194.50, 1895.00) 7.92 (0.92, 97.01) 3.45 (1.45, 27.75) ≥6m 807.00 (267.00, 1384.00) 11.39 (2.39, 71.21) 3.24 (1.24, 7.57) Treatment efficacy evaluation 0.011 0.096 0.003 Non-PD 352.50 (180.50, 1162.50) 3.59 (0.59, 61.80) 1.93 (0.93, 4.20) PD 1189.00 (784.00, 2120.00) 34.85 (5.85, 71.21) 9.16 (3.16, 23.20) Abbreviations: CEA:carcinoembryonic antigen; CSF: cerebrospinal fluid; HE4: human epididymis protein 4; LM: leptomeningeal metastasis; PD: progressive disease 3.5. Serial Monitoring of CSF HE4 in Guiding Treatment and Predicting Progression To explore the potential of CSF HE4 in therapeutic monitoring, serial measurements were performed in four LM patients undergoing intrathecal chemotherapy (Fig. 5). These longitudinal profiles demonstrated that serial CSF HE4 measurements could reflect dynamic changes in leptomeningeal tumor burden, offering valuable clinical insights. This suggests that CSF HE4 could be a useful tool for monitoring treatment response and providing early indications of LM progression. 4. Discussion LM in NSCLC is associated with a poor prognosis, compounded by diagnostic delays and the complexity of predicting treatment response, posing significant clinical challenges[13-15]. This study identified CSF HE4 as a promising biomarker for both diagnosis and monitoring. Findings suggest that elevated CSF HE4 levels appear to show an enhanced diagnostic performance, providing a potential molecular basis to guide treatment decisions and predict clinical responses in this high-risk population. The diagnostic challenge in LM is highlighted by the limited sensitivity of initial CSF cytology and the frequent non-diagnostic nature of MRI findings in a significant proportion of patients[16,17]. Compounding this challenge is the established clinical consensus that positive CSF cytology, when detectable, often indicates a higher leptomeningeal tumor burden and is independently associated with a poorer prognosis[18,19]. In this context, our study aimed to explore a novel biomarker across a broader clinical spectrum. Notably, unlike the pivotal work by Li et al., which focused exclusively on a cytology-confirmed cohort[11], our investigation included both cytology-positive and cytology-negative patients with high clinical/radiological suspicion of LM. Our findings show that CSF HE4 achieves an AUC of 0.895, significantly outperforming CSF CEA and CYFRA21-1. Importantly, we observed that HE4 levels were significantly higher in the CSF cytology-positive subgroup compared to the cytology-negative group, reinforcing its correlation with disease burden. Moreover, CSF HE4 retained promising diagnostic value even within the cytology-negative cohort, addressing a critical unmet need in patients with suspected LM but negative routine cytology. Furthermore, serial monitoring revealed statistically significant changes in CSF HE4 levels before and after treatment, suggesting its potential utility in therapeutic monitoring. A key discovery in our study is the marked discrepancy between CSF and serum HE4 levels in LM patients, with CSF concentrations significantly exceeding those in the systemic circulation. A weak but statistically significant correlation was observed between CSF and serum HE4 ( r = 0.376, P = 0.003). This suggests that elevated CSF HE4 is not merely a passive reflection of systemic levels but likely indicates disproportionate local secretion or accumulation within the subarachnoid space. It is hypothesized that HE4 is actively secreted or released following the lysis of metastatic tumor cells within the leptomeninges, where it becomes concentrated due to the relative containment of the CSF compartment. As a result, CSF HE4 levels may provide a more sensitive and direct indicator of leptomeningeal tumor activity compared to serum levels. The biological role of HE4 in tumor pathogenesis offers a plausible mechanism for its elevated levels in LM. In addition to its diagnostic value, HE4 is functionally involved in tumor progression. Research in ovarian and endometrial cancers has demonstrated that HE4 promotes cell proliferation, invasion, and metastasis[20-22]. In the context of lung cancer-related LM, the high local concentration of HE4 may contribute to tumor cell survival and colonization within the leptomeningeal space by modulating the local microenvironment, potentially through interactions with proteolytic pathways or immune evasion mechanisms. While the exact molecular pathways in LM remain to be fully elucidated, the persistently high CSF HE4 levels observed in progressing disease support its potential pro-tumorigenic role, suggesting that HE4 may not only serve as a diagnostic marker but also lead to the aggressive pathophysiology of LM. Beyond its diagnostic utility, the dynamic changes in CSF HE4 levels provide valuable insights into disease progression and treatment response. Our data point to an association between CSF HE4 levels and clinical outcomes, with significantly higher CSF HE4 levels observed in patients with PD compared to those with non-PD. This finding is consistent with serological studies in lung and ovarian cancers, where elevated serum HE4 levels are associated with advanced disease stages, treatment resistance, and poorer overall survival[23-25]. The longitudinal case profiles in our study extend this prognostic association to the CSF compartment, demonstrating that serial measurements of CSF HE4 could track real-time changes in leptomeningeal tumor burden and responses to intrathecal therapy. These findings position CSF HE4 as a promising tool for monitoring therapeutic efficacy and predicting disease progression in LM management. Interpretation of HE4 levels should be approached with caution, especially when considering the relationship between circulating HE4 and tumor biology. Evidence suggests that elevated serum HE4 concentrations may not always directly correlate with tumor tissue HE4 overexpression and may be influenced by factors such as tumor stage, necrosis, or malignant effusions[26-28]. This highlights the complexity of HE4 biology. In our study, the distinct behavior of CSF HE4, decoupled from serum levels in LM patients, supports the notion that its source is local. Therefore, in the context of LM, CSF HE4 is likely a more specific and reliable indicator of leptomeningeal disease activity than serum HE4, as it is less influenced by systemic tumor factors. Despite these compelling findings, several limitations should also be considered. First, the single-center design of this study necessitates further validation in larger, multi-institutional cohorts. Second, the influence of various systemic and intrathecal therapies on CSF HE4 kinetics remains to be fully understood. Clarifying these dynamics will be helpful in determining its specific role in monitoring therapeutic efficacy. Finally, it remains unclear whether our findings are applicable to LM originating from other solid tumors. 5. Conclusion In conclusion, this study validates CSF HE4 as a sensitive and specific biomarker for diagnosing NSCLC-related LM and, more importantly, pioneers its use in serial therapeutic monitoring. The robust diagnostic performance, high correlation with disease progression, and dynamic changes during treatment highlight CSF HE4’s significant clinical potential as a comprehensive tool to guide the management of this devastating complication. Abbreviations CEA: Carcinoembryonic antigen CSF: Cerebrospinal fluid HE4: Human Epididymis Protein 4 ICP: Intracranial pressure KPS: Karnofsky performance status LM: Leptomeningeal metastasis NSCLC: Non-small cell lung cancer ROC: Receiver operating characteristic Declarations Ethics approval and consent to participate The study protocol adhered to the principles of the Helsinki Declaration and was approved by the Ethics Committee of Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School (No.2024-544-02). Written informed consent was obtained from all participants. Consent for publication Not applicable. Availability of data and materials The datasets used and analysed during the current study are available from the corresponding author on reasonable request. Competing interests The authors declare no competing interests. Funding This research was funded by the National Natural Science Foundation of XX country Youth Program (82304567); Health Research Project of XX Province (LKZ2023013); Medical Key Science and Technology Development Project of XX (ZKX18014); Cadre Health Care Project of XX Province (BJ23033); Cancer Research Funding of XXX (Y-HS2019-5); Undergraduate Education Reform Research Project, School of Medicine, XX University (NDY202502); Project of XX Hospital Reform and Development Research Institute, XX University (NDYGN2024120); and Clinical Teaching Program, XX University (NZYJY2025-L-35). Relevant information is concealed for peer review. The funding bodies had no role in the design, implementation, writing, or submission for publication of the study. Authors' contributions YJL: Experimental design, manuscript writing, statistical analysis; LLH and XWL: Experimental operations, research guidance and manuscript revision; MYH: Data processing; ZYY and YX: Manuscript preparation and revision. Acknowledgements We express our gratitude to the study participants and clinical staff for their kind contributions to this study. References Remsik J, Boire A. The path to leptomeningeal metastasis. Nat Rev Cancer . 2024;24(7):448-60. Remsik J, Tong X, Kunes RZ, Li MJ, Estrera R, Snyder J, et al. Interferon-γ orchestrates leptomeningeal anti-tumour response. Nature. 2025;643(8073):1087-96. Cheng H, Perez-Soler R. Leptomeningeal metastases in non-small-cell lung cancer. Lancet Oncol. 2018;19(1):e43-e55. Freret ME, Boire A. The anatomic basis of leptomeningeal metastasis. J Exp Med. 20 2 4;221(4):e20212121. 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HE4 in the evaluation of tumor load and prognostic stratification of high grade serous ovarian carcinoma. Acta Oncol. 2020;59(12):1461-68. Lan T, Mu C, Wang Z, Wang Y, Li Y, Mai Y, et al. Diagnostic and Prognostic Values of Serum EpCAM, TGM2, and HE4 Levels in Endometrial Cancer. Front Oncol. 2020;10:1697. Alegría-Baños JA, Jiménez-López JC, Vergara-Castañeda A, de León DFC, Mohar-Betancourt A, Pérez-Montiel D, et al. Kinetics of HE4 and CA125 as prognosis biomarkers during neoadjuvant chemotherapy in advanced epithelial ovarian cancer. J Ovarian Res. 2021;14(1):96. Zhen S, Bian LH, Chang LL, Gao X. Comparison of serum human epididymis protein 4 and carbohydrate antigen 125 as markers in ovarian cancer: A meta-analysis. Mol Clin Oncol. 2014;2(4):559-66. Cao H, You D, Lan Z, Ye H, Hou M, Xi M. Prognostic value of serum and tissue HE4 expression in ovarian cancer: a systematic review with meta-analysis of 90 studies. Expert Rev Mol Diagn. 2018;18(4):371-83. Plotti F, Bartolone M, Terranova C, Luvero D, Scaletta G, Gatti A, et al . Role of human epididymis protein 4 (HE4) as predictor of response to platinum based chemotherapy: a systematic review of literature . Eur J Gynaecol Oncol. 2020; 41 (6): 889. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Revision Version 1 posted Editorial decision: Revision requested 17 Apr, 2026 Reviews received at journal 16 Apr, 2026 Reviewers agreed at journal 16 Apr, 2026 Reviewers agreed at journal 16 Apr, 2026 Reviews received at journal 14 Mar, 2026 Reviewers agreed at journal 14 Feb, 2026 Reviewers invited by journal 13 Feb, 2026 Editor invited by journal 03 Feb, 2026 Editor assigned by journal 03 Feb, 2026 Submission checks completed at journal 03 Feb, 2026 First submitted to journal 03 Feb, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8736012","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":591371828,"identity":"5f8aa6cf-0889-4eca-a259-49379b17a337","order_by":0,"name":"Yongjuan Lin","email":"","orcid":"","institution":"Nanjing Drum Tower Hospital","correspondingAuthor":false,"prefix":"","firstName":"Yongjuan","middleName":"","lastName":"Lin","suffix":""},{"id":591371829,"identity":"a1f7e59a-bc15-456c-87e7-5979117537a8","order_by":1,"name":"Mingyang He","email":"","orcid":"","institution":"Nanjing Drum Tower Hospital","correspondingAuthor":false,"prefix":"","firstName":"Mingyang","middleName":"","lastName":"He","suffix":""},{"id":591371830,"identity":"656d51de-3e44-4983-814b-99f5378a02c1","order_by":2,"name":"Yu Xie","email":"","orcid":"","institution":"Nanjing Drum Tower Hospital","correspondingAuthor":false,"prefix":"","firstName":"Yu","middleName":"","lastName":"Xie","suffix":""},{"id":591371831,"identity":"9075773c-6ad5-438d-b098-d9128bbd25b4","order_by":3,"name":"Zhenyu Yin","email":"","orcid":"","institution":"Nanjing Drum Tower Hospital","correspondingAuthor":false,"prefix":"","firstName":"Zhenyu","middleName":"","lastName":"Yin","suffix":""},{"id":591371832,"identity":"bad12725-0f55-48ef-9b3f-05fde33e184a","order_by":4,"name":"Xiawen Lin","email":"","orcid":"","institution":"Nanjing Drum Tower Hospital","correspondingAuthor":false,"prefix":"","firstName":"Xiawen","middleName":"","lastName":"Lin","suffix":""},{"id":591371833,"identity":"9a7003d7-46b3-4b9f-b605-e4456f23e98f","order_by":5,"name":"Lingli Hu","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA2klEQVRIiWNgGAWjYBACPmYg8cCAQY6fvfngg4QKG8Ja2EBaEgwYjCV7jiUbPDiTRoQWEJHAwJC44UaOmeTDtkNEaGHnPfwioYAhceaMtLSKBLYDDPzt3QkEHMaXZgFyWD/P42M3EnjuMEicObuBgBYeMwOgFtmZ7WlpNxIknjEYSOQSp4Vxw4Ecs4IEg8NEaTF+ANSiuOFEjhlDQgJxWszggSyRcCCNh6Bf+PnPGH/48AcSlR9//rOR42/vxa8FZJEEA8N/OI+HkHIQYP5AjKpRMApGwSgYwQAA3SBGRTfuWw8AAAAASUVORK5CYII=","orcid":"","institution":"Nanjing Drum Tower Hospital","correspondingAuthor":true,"prefix":"","firstName":"Lingli","middleName":"","lastName":"Hu","suffix":""}],"badges":[],"createdAt":"2026-01-30 01:53:41","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8736012/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8736012/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":103504742,"identity":"5b0c2d09-8f1f-4d97-a024-9e32dc78c029","added_by":"auto","created_at":"2026-02-26 13:21:12","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":245260,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eRecruitment flowchart of NSCLC patients with LM\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-8736012/v1/ebb1a14169bca1fab196b6fc.png"},{"id":103165464,"identity":"a8cfda41-4806-40aa-bc26-3189bc6c847a","added_by":"auto","created_at":"2026-02-22 12:28:26","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":154917,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eHE4 levels in CSF and Serum between patients with LM and control group\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFig 2A: The CSF HE4 level in LM patients and control group;\u003c/p\u003e\n\u003cp\u003eFig 2B. The Serum HE4 level in LM patients and control group;\u003c/p\u003e\n\u003cp\u003eFig 2C. The paired CSF and serum HE4 level in LM patients;\u003c/p\u003e\n\u003cp\u003eFig 2D. The correlation between CSF and serum HE4 level in LM patients.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-8736012/v1/45b15c982a336abecbde5f41.png"},{"id":103165453,"identity":"7527ddf8-2a40-4f67-8d04-d0f7b800ad57","added_by":"auto","created_at":"2026-02-22 12:28:26","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":123576,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eROC curve analysis of CSF HE4, CEA and CYFRA21-1 for the detection of LM\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-8736012/v1/534eda443609b21f8d8d36a0.png"},{"id":103504328,"identity":"5fc05cc0-8529-43b0-9422-ff7a8277acf3","added_by":"auto","created_at":"2026-02-26 13:19:14","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":265176,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSpearman correlation analysis of CSF HE4 and other biomarkers in LM patients\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eA: \u003c/strong\u003eHE4 and WBC;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eB: \u003c/strong\u003eHE4 and Glucose;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eC: \u003c/strong\u003eHE4 and Protein;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eD: \u003c/strong\u003eHE4 and IL-6;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eE: \u003c/strong\u003eHE4 and CEA;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eF: \u003c/strong\u003eHE4 and CYFRA21-1.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-8736012/v1/94f10b4dc1b8d3ccac0c7963.png"},{"id":103165456,"identity":"2868f716-4040-4f65-bb06-3f7da215420e","added_by":"auto","created_at":"2026-02-22 12:28:26","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":183089,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eCSF and serum HE4 level were determined prior to each intrathecal chemotherapy in four LM patients\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eA: \u003c/strong\u003eThe CSF CEA levels were higher than the serum in patient 1, but with successful intrathecal chemotherapy, HE4 levels decreased in CSF, while they increased in serum, heralding extrathecal lesions relapse;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eB: \u003c/strong\u003eThe CSF and serum level of HE4 were not significantly different in patient 2. With the progression of the disease, serum HE4 levels did not increase, while CSF HE4 level significantly increased, suggesting intracranial progression;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eC: \u003c/strong\u003eThe CSF HE4 level was increased at diagnosis of LM, while serum HE4 levels were normal and decreased progressively with treatment, indicating effective therapy. Then both CSF and serum CEA levels increased over time due to the progression of LM, with CSF HE4 level persistently being higher than in serum until death;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eD: \u003c/strong\u003eWith the progression of LM, both the serum and CSF level of HE4 gradually increased, meanwhile the level of HE4 in CSF were continuously higher than in serum until death.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-8736012/v1/87b7d3f4d53e426adb757bd9.png"},{"id":103509310,"identity":"a9a8d037-04b1-4b13-93ea-c862b944e054","added_by":"auto","created_at":"2026-02-26 13:58:08","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2505563,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8736012/v1/f1567b25-b65c-4757-b83d-6ea80945a064.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Evaluation of cerebrospinal fluid Human Epididymis Protein 4 for leptomeningeal metastasis in Non-Small Cell Lung Cancer: A retrospective cohort study","fulltext":[{"header":"1. Background","content":"\u003cp\u003eLeptomeningeal metastasis (LM) is a severe complication of non-small cell lung cancer (NSCLC), affecting 3-5% of patients with advanced disease and resulting in a poor prognosis[1,2]. Its diagnosis remains difficult, as cerebrospinal fluid (CSF) cytology has a low initial sensitivity (~50%), and magnetic resonance imaging (MRI) is non-diagnostic in a significant proportion of cases[3,4]. This highlights an urgent need for reliable CSF biomarkers to enhance LM detection.\u003c/p\u003e\n\u003cp\u003eHuman epididymis protein 4 (HE4), a secretory protein overexpressed in lung cancer, has emerged as a promising candidate. Beyond its established role in diagnosis, HE4 is increasingly recognized as a critical tool for dynamic disease monitoring and prognostic stratification across various malignancies[5,6]. In high-grade serous ovarian carcinoma, baseline serum HE4 levels correlate more strongly with surgical tumor burden than cancer antigen 125 (CA125) , providing a more accurate initial assessment of disease extent[7]. Notably, longitudinal monitoring shows that HE4 levels during primary therapy are a significant predictor of platinum-resistant relapse, while serum HE4 concentration at first recurrence serves as an independent prognostic factor for overall survival[8]. This prognostic value is further refined in the context of modern targeted therapies. For instance, during poly ADP-ribose polymerase (PARP) inhibitor maintenance treatment for epithelial ovarian cancer, serial HE4 measurement (using a \u0026ge;25% increase threshold) demonstrates significantly higher accuracy than CA125 in detecting disease progression, highlighting its superior reliability in this novel therapeutic setting[9]. The translational utility of HE4 dynamic monitoring is also evident in lung adenocarcinoma, where combining HE4 with CYFRA21-1 in post-resection surveillance improves recurrence detection, outperforming either marker alone[10]. Taken together, serial HE4 assessment offers a powerful, integrative approach for evaluating real-time tumor dynamics, predicting therapeutic resistance, and detecting early recurrence, thereby supporting a more proactive and personalized cancer management strategy.\u003c/p\u003e\n\u003cp\u003eA recent landmark study by Li et al. established the diagnostic value of CSF HE4 for LM in lung adenocarcinoma, demonstrating its superior performance and synergistic effect when combined with carcinoembryonic antigen related cell adhesion molecule 6 (CEACAM6) [11]. These promising findings positioned CSF HE4 as a potent diagnostic biomarker. Notably, the study of Li et al. exclusively enrolled patients with cytologically positive CSF, which inherently confirms LM diagnosis[11]. To comprehensively assess the biomarker\u0026rsquo;s performance in a more representative clinical spectrum, our study included both CSF cytology-positive and cytology-negative patients. However, despite these advances, current evidence on the application of CSF HE4 for monitoring treatment response and predicting progression in LM remains limited. Thus, our study aimed to validate the diagnostic accuracy of CSF HE4 in an independent cohort and, more importantly, to explore its potential for serial therapeutic monitoring, addressing one of the key unresolved clinical challenges in LM management.\u003c/p\u003e"},{"header":"2. Materials and methods","content":"\u003cp\u003e\u003cstrong\u003e2.1. Ethical approval\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA prospective cohort study was conducted using data from the Department of Geriatric Oncology at XX Hospital, a tertiary comprehensive hospital (hospital information is concealed for peer review). The study received approval from the Ethics Committee of XX Hospital (No. 2024-544-02; hospital information is concealed for peer review). Informed consent was obtained from the family members of all patients, and all procedures adhered to the ethical principles outlined in the Declaration of Helsinki.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.2. Patients\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eBetween March 2023 and December 2024, 61 consecutive NSCLC patients with a confirmed diagnosis of LM were enrolled. The LM diagnosis followed the European Association of Neuro-Oncology (EANO)-ESMO criteria[12]. Inclusion criteria were: 1) patients aged 18 years or older; 2) a confirmed pathological diagnosis of NSCLC; 3) LM diagnosis based on positive CSF cytology or, in the absence of cytology, the presence of typical neurological symptoms/signs combined with characteristic MRI findings. Exclusion criteria included: 1) a history of encephalitis, significant craniocerebral trauma, neurosurgical intervention, or cerebral radiotherapy within the previous six months; 2) concurrent active malignancies; 3) incomplete clinical data or insufficient biological samples for study analysis. Fig.1 shows the recruitment flowchart of NSCLC patients with LM. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eControl subjects were selected from patients presenting with other neurological conditions (e.g., cognitive impairment, benign intracranial tumors, meningitis) during the same study period. Control participants were required to have undergone lumbar puncture yielding sufficient CSF volume, with paired serum samples collected on the same day. Individuals with evidence of central nervous system malignancy or current metastatic disease were excluded.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.3. \u003cstrong\u003eClinical data collection\u003c/strong\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eLumbar puncture was performed as the standard initial diagnostic procedure to confirm LM in all suspected cases. Patients were transferred to the procedure room, where an assistant prepared the necessary equipment and assisted with positioning. Lumbar puncture was performed under aseptic conditions, and CSF flow confirmation was followed by measurement of opening pressure. Approximately 6-8 mL of CSF was collected for laboratory analysis, including cytological examination, HE4 measurement, tumor marker assessment, and circulating tumor cell detection. After needle removal, the puncture site was disinfected and covered with a sterile dressing. Patients were instructed to remain supine, without a pillow, for six hours following the procedure.\u003c/p\u003e\n\u003cp\u003ePaired CSF and peripheral blood samples were collected during intrathecal chemotherapy for dynamic HE4 monitoring. These samples were analyzed using previously described methods. The initial lumbar puncture in LM patients was used to establish a cytological diagnosis and obtain baseline measurements of HE4 and other tumor markers. Subsequent lumbar punctures or Ommaya reservoir accesses for intrathecal drug administration followed the same protocol, with CSF sampled prior to each chemotherapy cycle for HE4 and biomarker assessments.\u003c/p\u003e\n\u003cp\u003eClinical and demographic data, including age, sex, Karnofsky Performance Status (KPS), intracranial pressure (ICP), CSF routine parameters (white blood cell count, protein, glucose, chloride), and MRI findings, were extracted from electronic medical records.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.4. Laboratory measurement of biomarkers\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCSF and blood samples were centrifuged at 3000 rpm for 5 minutes to isolate the supernatant CSF and serum for analysis. The specimens were stored at room temperature for no more than 5 hours, or at 2\u0026ndash;8\u0026deg;C for up to 2 days. Alternatively, they could be stored at -20 to -70\u0026deg;C for up to 12 weeks. HE4 and CYFRA21-1 concentrations were measured using the Roche cobas e801 electrochemiluminescence immunoassay system (Roche Diagnostics GmbH, Mannheim, Germany), while \u003cstrong\u003ecarcinoembryonic antigen\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;(\u003c/strong\u003eCEA) was assessed using the Siemens Atellica Solution chemiluminescence immunoassay analyzer (Siemens Healthcare Diagnostics Inc., New York, USA). All assays were conducted using instrument-specific reagent kits and calibrators, with the following lot numbers: HE4 reagent Lot: 84899001, HE4 calibrator Lot: 768265; CYFRA21-1 reagent Lot: 81414301, CYFRA21-1 calibrator Lot: 794449; CEA reagent Lot: 69175223, CEA calibrator Lot: CAL D57940A20. Bio-Rad tumor marker control sets (Levels 547, Lot: 94991, and 549, Lot: 94993) were used for quality control. Testing was conducted in strict accordance with the standard operating procedures (SOP) for both reagents and instruments. All measurements were performed by technicians blinded to the study hypothesis and the clinical group allocation of participants, with blinding maintained until all data were collected and locked for analysis.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.5. Statistical Analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eStatistical analyses were performed using SPSS 25.0 (IBM Corp.) and GraphPad Prism 9.0. Continuous variables with non-normal distributions were expressed as medians and interquartile ranges (IQR) and compared using the Mann-Whitney \u003cem\u003eU\u003c/em\u003e test or Kruskal-Wallis test. Categorical variables were compared using the Chi-square test or Fisher\u0026apos;s exact test. Paired comparisons between CSF and serum levels were made using the Wilcoxon signed-rank test. Spearman\u0026apos;s rank correlation coefficient was used to assess correlations. The diagnostic performance of biomarkers was evaluated through receiver operating characteristic (ROC) curve analysis, and the area under the curve (AUC) values were compared using the DeLong test. A two-sided \u003cem\u003eP-\u003c/em\u003evalue of \u0026lt; 0.05 was considered statistically significant.\u003c/p\u003e"},{"header":"3. Results","content":"\u003cp\u003e\u003cstrong\u003e3.1. Patient Characteristics\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe clinical characteristics of the 61 LM patients and 56 controls are summarized in Table 1. No significant differences were observed between the two groups in terms of age, sex, or KPS. As expected, LM patients exhibited significantly higher ICP (\u003cem\u003eP\u003c/em\u003e = 0.003) and CSF protein levels (\u003cem\u003eP\u003c/em\u003e = 0.001), alongside lower CSF glucose levels (\u003cem\u003eP\u003c/em\u003e = 0.001) compared to controls.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 1. \u0026nbsp; The comparison of clinical characteristics between LM patients and control group.\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"582\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 27.9588%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGroup\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.729%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eLM (n=61)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.2144%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eControl (n=56)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.2916%;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003eZ /X\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.8062%;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003eP\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp; value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 27.9588%;\"\u003e\n \u003cp\u003eMale/Femal(n)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.729%;\"\u003e\n \u003cp\u003e26/35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.2144%;\"\u003e\n \u003cp\u003e28/28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.2916%;\"\u003e\n \u003cp\u003e0.639\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.8062%;\"\u003e\n \u003cp\u003e0.424\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 27.9588%;\"\u003e\n \u003cp\u003eAge, Mean \u0026plusmn; SEM (yr)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.729%;\"\u003e\n \u003cp\u003e56.00 (53.00, 62.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.2144%;\"\u003e\n \u003cp\u003e56.00 (47.50, 66.50)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.2916%;\"\u003e\n \u003cp\u003e0.966\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.8062%;\"\u003e\n \u003cp\u003e0.334\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 27.9588%;\"\u003e\n \u003cp\u003eICP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.729%;\"\u003e\n \u003cp\u003e150.00 (120.00, 230.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.2144%;\"\u003e\n \u003cp\u003e130.00 (100.00, 155.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.2916%;\"\u003e\n \u003cp\u003e2.993\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.8062%;\"\u003e\n \u003cp\u003e0.003\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 27.9588%;\"\u003e\n \u003cp\u003eKPS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.729%;\"\u003e\n \u003cp\u003e60.00 (50.00, 70.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.2144%;\"\u003e\n \u003cp\u003e60.00 (50.00, 70.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.2916%;\"\u003e\n \u003cp\u003e-0.073\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.8062%;\"\u003e\n \u003cp\u003e0.942\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 27.9588%;\"\u003e\n \u003cp\u003eCSF WBC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.729%;\"\u003e\n \u003cp\u003e5.00 (2.00, 8.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.2144%;\"\u003e\n \u003cp\u003e3.00 (2.00, 29.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.2916%;\"\u003e\n \u003cp\u003e-0.167\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.8062%;\"\u003e\n \u003cp\u003e0.867\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 27.9588%;\"\u003e\n \u003cp\u003eCSF Lymphocyte\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.729%;\"\u003e\n \u003cp\u003e4.00 (2.00, 7.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.2144%;\"\u003e\n \u003cp\u003e3.00 (1.00, 19.50)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.2916%;\"\u003e\n \u003cp\u003e-0.248\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.8062%;\"\u003e\n \u003cp\u003e0.804\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 27.9588%;\"\u003e\n \u003cp\u003eCSF Neutrophil\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.729%;\"\u003e\n \u003cp\u003e1.00 (0.00, 1.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.2144%;\"\u003e\n \u003cp\u003e1.00 (0.00, 3.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.2916%;\"\u003e\n \u003cp\u003e0.230\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.8062%;\"\u003e\n \u003cp\u003e0.818\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 27.9588%;\"\u003e\n \u003cp\u003eCSF Protein\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.729%;\"\u003e\n \u003cp\u003e563.70 (370.50, 885.50)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.2144%;\"\u003e\n \u003cp\u003e495.05 (337.45, 726.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.2916%;\"\u003e\n \u003cp\u003e-3.258\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.8062%;\"\u003e\n \u003cp\u003e0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 27.9588%;\"\u003e\n \u003cp\u003eCSF Glucose\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.729%;\"\u003e\n \u003cp\u003e2.92 (2.64, 3.42)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.2144%;\"\u003e\n \u003cp\u003e3.45 (2.94, 3.98)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.2916%;\"\u003e\n \u003cp\u003e-3.277\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.8062%;\"\u003e\n \u003cp\u003e0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 27.9588%;\"\u003e\n \u003cp\u003eCSF chloride\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.729%;\"\u003e\n \u003cp\u003e123.50 (119.40, 125.60)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.2144%;\"\u003e\n \u003cp\u003e125.50 (122.85, 127.25)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.2916%;\"\u003e\n \u003cp\u003e1.129\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.8062%;\"\u003e\n \u003cp\u003e0.259\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 27.9588%;\"\u003e\n \u003cp\u003eCSF HE4 (pmol/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.729%;\"\u003e\n \u003cp\u003e807.00 (206.00, 1580.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.2144%;\"\u003e\n \u003cp\u003e99.35 (79.55, 124.50)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.2916%;\"\u003e\n \u003cp\u003e7.361\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.8062%;\"\u003e\n \u003cp\u003e0.000\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 27.9588%;\"\u003e\n \u003cp\u003eCSF CEA (U/ml)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.729%;\"\u003e\n \u003cp\u003e11.28 (1.62, 71.21)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.2144%;\"\u003e\n \u003cp\u003e2.50 (1.50, 2.50)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.2916%;\"\u003e\n \u003cp\u003e3.803\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.8062%;\"\u003e\n \u003cp\u003e0.000\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 27.9588%;\"\u003e\n \u003cp\u003eCSF CYFRA21-1 (U/ml)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.729%;\"\u003e\n \u003cp\u003e3.16 (1.30, 12.50)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.2144%;\"\u003e\n \u003cp\u003e1.63 (1.50, 1.74)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.2916%;\"\u003e\n \u003cp\u003e4.147\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.8062%;\"\u003e\n \u003cp\u003e0.000\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 27.9588%;\"\u003e\n \u003cp\u003eSerum HE4 (U/ml)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.729%;\"\u003e\n \u003cp\u003e128.00 (98.10, 182.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.2144%;\"\u003e\n \u003cp\u003e61.05 (46.15, 75.65)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.2916%;\"\u003e\n \u003cp\u003e7.707\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.8062%;\"\u003e\n \u003cp\u003e0.000\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 27.9588%;\"\u003e\n \u003cp\u003eSerum CEA (U/ml)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.729%;\"\u003e\n \u003cp\u003e30.81 (2.36, 76.08)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.2144%;\"\u003e\n \u003cp\u003e7.50 (1.89, 7.50)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.2916%;\"\u003e\n \u003cp\u003e3.945\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.8062%;\"\u003e\n \u003cp\u003e0.000\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 27.9588%;\"\u003e\n \u003cp\u003eSerum CYFRA21-1 (U/ml)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.729%;\"\u003e\n \u003cp\u003e2.66 (1.93, 3.41)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.2144%;\"\u003e\n \u003cp\u003e1.76 (1.35, 2.33)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.2916%;\"\u003e\n \u003cp\u003e4.567\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.8062%;\"\u003e\n \u003cp\u003e0.000\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003eAbbreviations:\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCEA:carcinoembryonic antigen;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eCSF: cerebrospinal fluid;\u003c/p\u003e\n\u003cp\u003eHE4: human epididymis protein 4;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eICP: intracranial pressure;\u003c/p\u003e\n\u003cp\u003eKPS: Karnofsky Performance Status;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eLM: leptomeningeal metastasis;\u003c/p\u003e\n\u003cp\u003eSEM: standard\u0026nbsp;error\u0026nbsp;of the mean;\u003c/p\u003e\n\u003cp\u003eWBC: white blood cell\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.2. Elevated CSF HE4 Levels in LM Patients\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCSF HE4 levels were markedly elevated in the LM group compared to controls [807.00 (206.00-1580.00) vs. 99.35 (79.55-124.50), \u003cem\u003eZ\u003c/em\u003e = 7.361, \u003cem\u003eP\u003c/em\u003e \u0026lt; 0.001; Fig. 2A]. Similarly, serum HE4 levels were higher in LM patients than in controls [128.00 (98.10-182.00) vs. 61.05 (46.15-75.65), \u003cem\u003eZ\u003c/em\u003e = 7.707, \u003cem\u003eP\u003c/em\u003e \u0026lt; 0.001; Fig. 2B]. Notably, in LM patients, CSF HE4 levels significantly exceeded those in the paired serum samples (\u003cem\u003eP\u003c/em\u003e \u0026lt; 0.001; Fig. 2C), with a weak but statistically significant correlation between the two compartments (\u003cem\u003er\u003c/em\u003e = 0.376, \u003cem\u003eP\u003c/em\u003e = 0.003; Fig. 2D). This CSF-serum gradient was not observed in the control group.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.3. Diagnostic Performance of CSF Biomarkers\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eROC curve analysis was performed to evaluate the diagnostic performance of the three CSF biomarkers\u0026nbsp;(Table 2, Fig. 3).\u0026nbsp;CSF HE4 demonstrated excellent diagnostic accuracy, with an AUC of 0.895 (95% confidence intervals: 0.830-0.960). At an optimal cutoff value of 173.00 pmol/L, the sensitivity and specificity for diagnosing LM were 83.21% and 92.86%, respectively. In contrast, the diagnostic power of CSF CEA (AUC 0.701, sensitivity 63.96%, specificity 89.29% at 3.01 U/mL) and CSF CYFRA21-1 (AUC 0.664, sensitivity 73.77%, specificity 67.21% at 1.78 U/mL) was significantly lower (\u003cem\u003eP\u003c/em\u003e \u0026lt; 0.05 for both comparisons with HE4).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2. ROC curves for CSF HE4 level for differentiating LM patients from control group.\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" align=\"\" width=\"696\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 77px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 79px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 69px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 167px;\"\u003e\n \u003cp\u003e95%\u003cem\u003eCIs\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003eInfluence factor\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003eAUC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003eCut-off value\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 77px;\"\u003e\n \u003cp\u003eSensitivity\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 79px;\"\u003e\n \u003cp\u003eSpecificity\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 69px;\"\u003e\n \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84px;\"\u003e\n \u003cp\u003eLower limit\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 82px;\"\u003e\n \u003cp\u003eUpper limit\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003eCSF HE4 (pmol/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e0.895\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e173.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 77px;\"\u003e\n \u003cp\u003e83.21%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 79px;\"\u003e\n \u003cp\u003e92.86%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 69px;\"\u003e\n \u003cp\u003e＜0.0001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84px;\"\u003e\n \u003cp\u003e0.830\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 82px;\"\u003e\n \u003cp\u003e0.960\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003eCSF CEA (U/ml)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e0.701\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e3.01\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 77px;\"\u003e\n \u003cp\u003e63.96%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 79px;\"\u003e\n \u003cp\u003e89.29%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 69px;\"\u003e\n \u003cp\u003e0.0002\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84px;\"\u003e\n \u003cp\u003e0.597\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 82px;\"\u003e\n \u003cp\u003e0.805\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003eCSF CYFRA21-1 (U/ml)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e0.664\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e1.78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 77px;\"\u003e\n \u003cp\u003e73.77%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 79px;\"\u003e\n \u003cp\u003e67.21%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 69px;\"\u003e\n \u003cp\u003e0.0018\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84px;\"\u003e\n \u003cp\u003e0.560\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 82px;\"\u003e\n \u003cp\u003e0.767\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003eAbbreviations:\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAUC: area under the curve;\u003c/p\u003e\n\u003cp\u003eCEA:carcinoembryonic antigen;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eCI:Confidence interval;\u003c/p\u003e\n\u003cp\u003eCSF: cerebrospinal fluid;\u003c/p\u003e\n\u003cp\u003eHE4: human epididymis protein 4;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eLM: leptomeningeal metastasis;\u003c/p\u003e\n\u003cp\u003eROC: receiver operating characteristic\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.4. Correlation of CSF HE4 with Other Parameters and Clinical Subgroups\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eSpearman correlation analysis in LM patients revealed that CSF HE4 levels showed a weak positive correlation with CSF white blood cell count (\u003cem\u003er\u003c/em\u003e = 0.385, \u003cem\u003eP\u003c/em\u003e = 0.002), protein (\u003cem\u003er\u003c/em\u003e = 0.354, \u003cem\u003eP\u0026nbsp;\u003c/em\u003e= 0.005) and IL6 (\u003cem\u003er\u003c/em\u003e = 0.255, \u003cem\u003eP\u003c/em\u003e = 0.048). Additionally, moderate positive correlations were observed with CSF CEA (\u003cem\u003er\u003c/em\u003e = 0.412, \u003cem\u003eP\u003c/em\u003e = 0.001) and CYFRA21-1 (\u003cem\u003er\u0026nbsp;\u003c/em\u003e= 0.623, \u003cem\u003eP\u003c/em\u003e \u0026lt; 0.0001). In contrast, CSF HE4 showed a moderate negative correlation with CSF glucose levels (\u003cem\u003er\u0026nbsp;\u003c/em\u003e=\u0026minus;0.493, \u003cem\u003eP\u003c/em\u003e \u0026lt; 0.0001). Fig 4 illustrates the details.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eSubgroup analyses assessed CSF HE4 levels under different clinical conditions (Table 3). No significant differences were observed based on the presence of concurrent brain metastases (\u003cem\u003eP\u003c/em\u003e = 0.318), specific MRI findings (\u003cem\u003eP\u003c/em\u003e = 0.253), or the duration of LM symptoms (\u003cem\u003eP\u003c/em\u003e = 0.658). However, CSF HE4 levels were significantly higher in patients with positive CSF cytology compared to those diagnosed clinically or radiographically with negative cytology [964.50 (320.50-1600.00) vs. 152.80 (77.80-214.00) pmol/L, \u003cem\u003eP\u003c/em\u003e = 0.015]. Notably, patients with progressive disease (PD) had substantially higher CSF HE4 levels than those with non-PD [1189.00 (784.00-2120.00) vs. 352.50 (180.50-1162.50), \u003cem\u003eP\u003c/em\u003e = 0.011].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 3. \u0026nbsp; Comparison of CSF HE4, CEA, and CYFRA21-1 levels in different groups\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"720\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" style=\"width: 139px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCases (n=61)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 202px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCSF HE4\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 173px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCSF CEA\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 174px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCSF CYFRA21-1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 157px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003e\u0026nbsp;\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 45px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003eP\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003e\u0026nbsp;\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 125px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003e\u0026nbsp;\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 48px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003eP\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 119px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003eP\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 139px;\"\u003e\n \u003cp\u003eAccompanying brain\u0026nbsp;\u003cbr\u003e\u0026nbsp;metastasis\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 157px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 45px;\"\u003e\n \u003cp\u003e0.318\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 125px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 48px;\"\u003e\n \u003cp\u003e0.537\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 119px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e0.701\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 139px;\"\u003e\n \u003cp\u003eYes\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 157px;\"\u003e\n \u003cp\u003e765.00 (239.00, 1171.50)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 45px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 125px;\"\u003e\n \u003cp\u003e11.83 (1.83, 112.17)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 48px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 119px;\"\u003e\n \u003cp\u003e3.79 (1.79, 11.85)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 139px;\"\u003e\n \u003cp\u003eNo\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 157px;\"\u003e\n \u003cp\u003e990.00 (206.00, 2120.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 45px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 125px;\"\u003e\n \u003cp\u003e9.72 (0.72, 65.26)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 48px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 119px;\"\u003e\n \u003cp\u003e2.24 (1.24, 14.60)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 139px;\"\u003e\n \u003cp\u003eMRI finding at LM\u0026nbsp;\u003cbr\u003e\u0026nbsp;diagnosis\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 157px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 45px;\"\u003e\n \u003cp\u003e0.253\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 125px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 48px;\"\u003e\n \u003cp\u003e0.489\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 119px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e0.644\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 139px;\"\u003e\n \u003cp\u003eYes\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 157px;\"\u003e\n \u003cp\u003e784.00 (206.00, 1384.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 45px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 125px;\"\u003e\n \u003cp\u003e11.70 (1.70, 71.21)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 48px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 119px;\"\u003e\n \u003cp\u003e3.30 (1.30, 11.20)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 139px;\"\u003e\n \u003cp\u003eNo\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 157px;\"\u003e\n \u003cp\u003e1046.00 (278.00, 3444.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 45px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 125px;\"\u003e\n \u003cp\u003e3.87 (0.87, 110.09)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 48px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 119px;\"\u003e\n \u003cp\u003e4.44 (1.44, 18.95)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 139px;\"\u003e\n \u003cp\u003ePositive for CSF cytology\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 157px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 45px;\"\u003e\n \u003cp\u003e0.015\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 125px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 48px;\"\u003e\n \u003cp\u003e0.005\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 119px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e0.045\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 139px;\"\u003e\n \u003cp\u003eYes\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 157px;\"\u003e\n \u003cp\u003e964.50 (320.50, 1600.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 45px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 125px;\"\u003e\n \u003cp\u003e11.27 (2.27, 107.37)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 48px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 119px;\"\u003e\n \u003cp\u003e3.72 (1.72, 13.55)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 139px;\"\u003e\n \u003cp\u003eNo\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 157px;\"\u003e\n \u003cp\u003e152.80 (77.80, 214.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 45px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 125px;\"\u003e\n \u003cp\u003e0.50 (0.50, 4.38)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 48px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 119px;\"\u003e\n \u003cp\u003e1.73 (0.73, 1.92)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 139px;\"\u003e\n \u003cp\u003eTreatment approaches\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 157px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 45px;\"\u003e\n \u003cp\u003e0.053\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 125px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 48px;\"\u003e\n \u003cp\u003e0.457\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 119px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e0.165\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 139px;\"\u003e\n \u003cp\u003eOmmaya\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 157px;\"\u003e\n \u003cp\u003e295.50 (180.50, 485.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 45px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 125px;\"\u003e\n \u003cp\u003e5.45 (1.45, 28.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 48px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 119px;\"\u003e\n \u003cp\u003e1.10 (1.10, 3.02)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 139px;\"\u003e\n \u003cp\u003eLumbar puncture\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 157px;\"\u003e\n \u003cp\u003e972.00 (214.00, 1630.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 45px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 125px;\"\u003e\n \u003cp\u003e11.62 (1.62, 72.21)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 48px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 119px;\"\u003e\n \u003cp\u003e3.58 (1.58, 17.50)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 139px;\"\u003e\n \u003cp\u003eLM symtoms to diagnosis\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 157px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 45px;\"\u003e\n \u003cp\u003e0.658\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 125px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 48px;\"\u003e\n \u003cp\u003e0.482\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 119px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e0.447\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 139px;\"\u003e\n \u003cp\u003e＜6m\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 157px;\"\u003e\n \u003cp\u003e893.50 (194.50, 1895.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 45px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 125px;\"\u003e\n \u003cp\u003e7.92 (0.92, 97.01)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 48px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 119px;\"\u003e\n \u003cp\u003e3.45 (1.45, 27.75)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 139px;\"\u003e\n \u003cp\u003e\u0026ge;6m\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 157px;\"\u003e\n \u003cp\u003e807.00 (267.00, 1384.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 45px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 125px;\"\u003e\n \u003cp\u003e11.39 (2.39, 71.21)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 48px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 119px;\"\u003e\n \u003cp\u003e3.24 (1.24, 7.57)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 139px;\"\u003e\n \u003cp\u003eTreatment efficacy evaluation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 157px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 45px;\"\u003e\n \u003cp\u003e0.011\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 125px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 48px;\"\u003e\n \u003cp\u003e0.096\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 119px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e0.003\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 139px;\"\u003e\n \u003cp\u003eNon-PD\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 157px;\"\u003e\n \u003cp\u003e352.50 (180.50, 1162.50)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 45px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 125px;\"\u003e\n \u003cp\u003e3.59 (0.59, 61.80)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 48px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 119px;\"\u003e\n \u003cp\u003e1.93 (0.93, 4.20)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 139px;\"\u003e\n \u003cp\u003ePD\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 157px;\"\u003e\n \u003cp\u003e1189.00 (784.00, 2120.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 45px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 125px;\"\u003e\n \u003cp\u003e34.85 (5.85, 71.21)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 48px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 119px;\"\u003e\n \u003cp\u003e9.16 (3.16, 23.20)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003eAbbreviations:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCEA:carcinoembryonic antigen;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eCSF: cerebrospinal fluid;\u003c/p\u003e\n\u003cp\u003eHE4: human epididymis protein 4;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eLM: leptomeningeal metastasis;\u003c/p\u003e\n\u003cp\u003ePD: progressive disease\u003c/p\u003e\n\u003ch3\u003e\u003cstrong\u003e3.5. Serial Monitoring of CSF HE4 in Guiding Treatment and Predicting Progression\u003c/strong\u003e\u003c/h3\u003e\n\u003cp\u003eTo explore the potential of CSF HE4 in therapeutic monitoring, serial measurements were performed in four LM patients undergoing intrathecal chemotherapy (Fig. 5). These longitudinal profiles demonstrated that serial CSF HE4 measurements could reflect dynamic changes in leptomeningeal tumor burden, offering valuable clinical insights. This suggests that CSF HE4 could be a useful tool for monitoring treatment response and providing early indications of LM progression.\u003c/p\u003e"},{"header":"4. Discussion","content":"\u003cp\u003eLM in NSCLC is associated with a poor prognosis, compounded by diagnostic delays and the complexity of predicting treatment response, posing significant clinical challenges[13-15]. This study identified CSF HE4 as a promising biomarker for both diagnosis and monitoring. Findings suggest that elevated CSF HE4 levels appear to show an enhanced diagnostic performance, providing a potential molecular basis to guide treatment decisions and predict clinical responses in this high-risk population.\u003c/p\u003e\n\u003cp\u003eThe diagnostic challenge in LM is highlighted by the limited sensitivity of initial CSF cytology and the frequent non-diagnostic nature of MRI findings in a significant proportion of patients[16,17]. Compounding this challenge is the established clinical consensus that positive CSF cytology, when detectable, often indicates a higher leptomeningeal tumor burden and is independently associated with a poorer prognosis[18,19]. In this context, our study aimed to explore a novel biomarker across a broader clinical spectrum. Notably, unlike the pivotal work by Li et al., which focused exclusively on a cytology-confirmed cohort[11], our investigation included both cytology-positive and cytology-negative patients with high clinical/radiological suspicion of LM.\u003c/p\u003e\n\u003cp\u003eOur findings show that CSF HE4 achieves an AUC of 0.895, significantly outperforming CSF CEA and CYFRA21-1. Importantly, we observed that HE4 levels were significantly higher in the CSF cytology-positive subgroup compared to the cytology-negative group, reinforcing its correlation with disease burden. Moreover, CSF HE4 retained promising diagnostic value even within the cytology-negative cohort, addressing a critical unmet need in patients with suspected LM but negative routine cytology. Furthermore, serial monitoring revealed statistically significant changes in CSF HE4 levels before and after treatment, suggesting its potential utility in therapeutic monitoring.\u003c/p\u003e\n\u003cp\u003eA key discovery in our study is the marked discrepancy between CSF and serum HE4 levels in LM patients, with CSF concentrations significantly exceeding those in the systemic circulation. A weak but statistically significant correlation was observed between CSF and serum HE4 (\u003cem\u003er\u003c/em\u003e = 0.376, \u003cem\u003eP\u003c/em\u003e = 0.003). This suggests that elevated CSF HE4 is not merely a passive reflection of systemic levels but likely indicates disproportionate local secretion or accumulation within the subarachnoid space. It is hypothesized that HE4 is actively secreted or released following the lysis of metastatic tumor cells within the leptomeninges, where it becomes concentrated due to the relative containment of the CSF compartment. As a result, CSF HE4 levels may provide a more sensitive and direct indicator of leptomeningeal tumor activity compared to serum levels.\u003c/p\u003e\n\u003cp\u003eThe biological role of HE4 in tumor pathogenesis offers a plausible mechanism for its elevated levels in LM. In addition to its diagnostic value, HE4 is functionally involved in tumor progression. Research in ovarian and endometrial cancers has demonstrated that HE4 promotes cell proliferation, invasion, and metastasis[20-22]. In the context of lung cancer-related LM, the high local concentration of HE4 may contribute to tumor cell survival and colonization within the leptomeningeal space by modulating the local microenvironment, potentially through interactions with proteolytic pathways or immune evasion mechanisms. While the exact molecular pathways in LM remain to be fully elucidated, the persistently high CSF HE4 levels observed in progressing disease support its potential pro-tumorigenic role, suggesting that HE4 may not only serve as a diagnostic marker but also lead to the aggressive pathophysiology of LM.\u003c/p\u003e\n\u003cp\u003eBeyond its diagnostic utility, the dynamic changes in CSF HE4 levels provide valuable insights into disease progression and treatment response. Our data point to an association between CSF HE4 levels and clinical outcomes, with significantly higher CSF HE4 levels observed in patients with PD compared to those with non-PD. This finding is consistent with serological studies in lung and ovarian cancers, where elevated serum HE4 levels are associated with advanced disease stages, treatment resistance, and poorer overall survival[23-25]. The longitudinal case profiles in our study extend this prognostic association to the CSF compartment, demonstrating that serial measurements of CSF HE4 could track real-time changes in leptomeningeal tumor burden and responses to intrathecal therapy. These findings position CSF HE4 as a promising tool for monitoring therapeutic efficacy and predicting disease progression in LM management.\u003c/p\u003e\n\u003cp\u003eInterpretation of HE4 levels should be approached with caution, especially when considering the relationship between circulating HE4 and tumor biology. Evidence suggests that elevated serum HE4 concentrations may not always directly correlate with tumor tissue HE4 overexpression and may be influenced by factors such as tumor stage, necrosis, or malignant effusions[26-28]. This highlights the complexity of HE4 biology. In our study, the distinct behavior of CSF HE4, decoupled from serum levels in LM patients, supports the notion that its source is local. Therefore, in the context of LM, CSF HE4 is likely a more specific and reliable indicator of leptomeningeal disease activity than serum HE4, as it is less influenced by systemic tumor factors.\u003c/p\u003e\n\u003cp\u003eDespite these compelling findings, several limitations should also be considered. First, the single-center design of this study necessitates further validation in larger, multi-institutional cohorts. Second, the influence of various systemic and intrathecal therapies on CSF HE4 kinetics remains to be fully understood. Clarifying these dynamics will be helpful in determining its specific role in monitoring therapeutic efficacy. Finally, it remains unclear whether our findings are applicable to LM originating from other solid tumors.\u003c/p\u003e"},{"header":"5. Conclusion","content":"\u003cp\u003eIn conclusion, this study validates CSF HE4 as a sensitive and specific biomarker for diagnosing NSCLC-related LM and, more importantly, pioneers its use in serial therapeutic monitoring. The robust diagnostic performance, high correlation with disease progression, and dynamic changes during treatment highlight CSF HE4\u0026rsquo;s significant clinical potential as a comprehensive tool to guide the management of this devastating complication.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003e\u003cstrong\u003eCEA:\u0026nbsp;\u003c/strong\u003eCarcinoembryonic antigen \u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCSF:\u0026nbsp;\u003c/strong\u003eCerebrospinal fluid\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eHE4:\u0026nbsp;\u003c/strong\u003eHuman Epididymis Protein 4\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eICP:\u0026nbsp;\u003c/strong\u003eIntracranial pressure\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eKPS:\u0026nbsp;\u003c/strong\u003eKarnofsky performance status\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eLM:\u0026nbsp;\u003c/strong\u003eLeptomeningeal metastasis\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eNSCLC:\u0026nbsp;\u003c/strong\u003eNon-small cell lung cancer\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eROC:\u0026nbsp;\u003c/strong\u003eReceiver operating characteristic \u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study protocol adhered to the principles of the Helsinki Declaration and was approved by the Ethics Committee of Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School (No.2024-544-02). Written informed consent was obtained from all participants.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and analysed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis research was funded by the National Natural Science Foundation of XX country Youth Program (82304567); Health Research Project of XX Province (LKZ2023013); Medical Key Science and Technology Development Project of XX (ZKX18014); Cadre Health Care Project of XX Province (BJ23033); Cancer Research Funding of XXX (Y-HS2019-5); Undergraduate Education Reform Research Project, School of Medicine, XX University (NDY202502); Project of XX Hospital Reform and Development Research Institute, XX University (NDYGN2024120); and Clinical Teaching Program, XX University (NZYJY2025-L-35). Relevant information is concealed for peer review.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe funding bodies had no role in the design, implementation, writing, or submission for publication of the study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026apos; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eYJL: Experimental design, manuscript writing, statistical analysis; LLH and XWL: Experimental operations, research guidance and manuscript revision; MYH: Data processing; ZYY and YX: Manuscript preparation and revision.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe express our gratitude to the study participants and clinical staff for their kind contributions to this study.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003e\u003cstrong\u003e\u003c/strong\u003e\u003cstrong\u003eRemsik J, Boire A. \u003c/strong\u003eThe path to leptomeningeal metastasis. 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Prognostic Values of Serum EpCAM, TGM2, and HE4 Levels in Endometrial Cancer. \u003cstrong\u003e\u003cem\u003eFront Oncol. \u003c/em\u003e\u003c/strong\u003e2020;10:1697. \u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003e Alegr\u0026iacute;a-Ba\u0026ntilde;os JA, Jim\u0026eacute;nez-L\u0026oacute;pez JC, Vergara-Casta\u0026ntilde;eda A, de Le\u0026oacute;n DFC, Mohar-Betancourt A, P\u0026eacute;rez-Montiel D, et al.\u003c/strong\u003e Kinetics of HE4 and CA125 as prognosis biomarkers during neoadjuvant chemotherapy in advanced epithelial ovarian cancer. \u003cstrong\u003e\u003cem\u003eJ Ovarian Res.\u003c/em\u003e\u003c/strong\u003e 2021;14(1):96. \u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003e Zhen S, Bian LH, Chang LL, Gao X. \u003c/strong\u003eComparison of serum human epididymis protein 4 and carbohydrate antigen 125 as markers in ovarian cancer: A meta-analysis.\u003cstrong\u003e\u003cem\u003e Mol Clin Oncol. \u003c/em\u003e\u003c/strong\u003e2014;2(4):559-66. \u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003e Cao H, You D, Lan Z, Ye H, Hou M, Xi M. \u003c/strong\u003ePrognostic value of serum and tissue HE4 expression in ovarian cancer: a systematic review with meta-analysis of 90 studies. \u003cstrong\u003e\u003cem\u003eExpert Rev Mol Diagn. \u003c/em\u003e\u003c/strong\u003e2018;18(4):371-83. \u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003e Plotti F, Bartolone M, Terranova C, Luvero D, Scaletta G, Gatti A, et al\u003c/strong\u003e \u003cstrong\u003e. \u003c/strong\u003eRole of human epididymis protein 4 (HE4) as predictor of response to platinum based chemotherapy: a systematic review of literature\u003cem\u003e. \u003cstrong\u003eEur J Gynaecol Oncol. \u003c/strong\u003e\u003c/em\u003e\u003cem\u003e2020;\u003c/em\u003e 41 (6): 889.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-cancer","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bcan","sideBox":"Learn more about [BMC Cancer](http://bmccancer.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bcan/default.aspx","title":"BMC Cancer","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Leptomeningeal metastasis, Non-small cell lung cancer, Cerebrospinal fluid, Human epididymis protein 4, Biomarker, Diagnosis","lastPublishedDoi":"10.21203/rs.3.rs-8736012/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8736012/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground\u003c/strong\u003e: Diagnosing and monitoring leptomeningeal metastasis presents a significant clinical challenge. This study evaluated cerebrospinal fluid (CSF) Human Epididymis Protein 4 (HE4) as a novel diagnostic and monitoring biomarker for leptomeningeal metastasis in non-small cell lung cancer.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods\u003c/strong\u003e: A prospective cohort study enrolled 117 participants (including 61 non-small cell lung cancer patients with leptomeningeal metastasis and 56 controls without central nervous systemmalignancies) from March 2023 to December 2024. Paired CSF and serum levels of HE4, carcinoembryonic antigen (CEA), and CYFRA21-1 were measured using electrochemiluminescence immunoassay. Diagnostic performance was assessed using receiver operating characteristic (ROC) curve analysis. Serial monitoring was also performed in a subset of patients.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e: CSF HE4 levels were significantly higher in leptomeningeal metastasis patients compared to controls (median 807.00 vs. 99.35 pmol/L,\u003cem\u003e P\u003c/em\u003e \u0026lt; 0.001) and markedly exceeded paired serum levels, indicating a distinct CSF-serum gradient. For leptomeningeal metastasis diagnosis, CSF HE4 (AUC = 0.895) demonstrated superior performance to CSF CEA and CYFRA21-1. At an optimal cutoff of 173.00 pmol/L, the sensitivity and specificity were 83.21% and 92.86%, respectively. Subgroup analysis revealed significantly higher CSF HE4 levels in patients with positive CSF cytology, particularly those with progressive disease. Serial monitoring demonstrated that dynamic changes in CSF HE4 levels correlated with treatment response during intrathecal chemotherapy.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion\u003c/strong\u003e: CSF HE4 is a promising biomarker for the diagnosis of non-small cell lung cancer related leptomeningeal metastasis. For CSF HE4, its robust diagnostic performance and correlation with disease activity support its use for both initial diagnosis and therapeutic monitoring.\u003c/p\u003e","manuscriptTitle":"Evaluation of cerebrospinal fluid Human Epididymis Protein 4 for leptomeningeal metastasis in Non-Small Cell Lung Cancer: A retrospective cohort study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-02-22 12:28:18","doi":"10.21203/rs.3.rs-8736012/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-04-17T04:55:57+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-16T19:36:00+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"37853999795217684112332568982964450484","date":"2026-04-16T16:48:32+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"26331139400508578176248702590162717013","date":"2026-04-16T16:48:03+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-14T10:03:53+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"336094498799824613240903041195906316014","date":"2026-02-14T13:45:23+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-02-13T13:56:19+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-02-03T18:57:37+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-02-03T18:52:23+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-02-03T15:39:58+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Cancer","date":"2026-02-03T15:25:38+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-cancer","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bcan","sideBox":"Learn more about [BMC Cancer](http://bmccancer.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bcan/default.aspx","title":"BMC Cancer","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"7e6b7b6a-e562-455a-bfb0-e4c4be891e71","owner":[],"postedDate":"February 22nd, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"in-revision","subjectAreas":[],"tags":[],"updatedAt":"2026-04-17T05:09:02+00:00","versionOfRecord":[],"versionCreatedAt":"2026-02-22 12:28:18","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8736012","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8736012","identity":"rs-8736012","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}