Neuroendocrine differentiation and PD-L1 expression in treatment-naïve prostatic adenocarcinoma: Clinicopathological correlates and prognostic significance

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This study aimed to evaluate the associations of NED extent, synaptophysin intensity score (SIS), and PD-L1 expression with other histomorphological features and prognosis in treatment-naïve PaNED. Materials and Methods Seventeen patients with PaNED diagnosed between 2014 and 2024 were retrospectively analyzed. NED was classified as diffuse (≥ 30%) or focal (< 30%), and SIS was scored as weak (+ 1), moderate (+ 2), or strong (+ 3). PD-L1 expression was assessed using tumor proportion score (TPS, cut-off ≥ 1%) and combined positive score (CPS, cut-off ≥ 10). Clinicopathological data and survival outcomes were evaluated. Results The mean age was 65.2 ± 6.6 years, and 47.1% (n = 8) of the cases were Grade Group 5. Diffuse NED was observed in 70.6% of cases, and strong synaptophysin expression in 35.3%. PD-L1 TPS and CPS positivity were detected in 17.6% and 35.3% of patients, respectively. Neither NED extent nor percentage was significantly associated with PD-L1 expression or prognosis. A moderate negative correlation was found between SIS and PD-L1 CPS (rho = -0.48, p = 0.051). Strong synaptophysin expression was significantly associated with shorter overall survival (p = 0.031). Conclusions In treatment-naïve PaNED, higher SIS was correlated with lower PD-L1 CPS values, and strong synaptophysin expression was associated with poorer survival. Assessment of SIS in morphologically suspected neuroendocrine areas may provide additional prognostic information and help predict the PD-L1 response. Larger studies are required to validate these findings. Prostatic adenocarcinoma Neuroendocrine differentiation Synaptophysin Programmed death-ligand 1 (PD-L1) Treatment-naïve Prognosis Figures Figure 1 Figure 2 Figure 3 INTRODUCTION Prostatic adenocarcinoma with neuroendocrine differentiation (PaNED) is characterized by conventional adenocarcinoma cells exhibiting neuroendocrine features, such as round to oval nuclei, finely granular chromatin, and scant to moderate eosinophilic cytoplasm. These tumors often display nested, trabecular, rosette-like, or solid growth patterns. The diagnosis of NED relies on these histological features and the expression of at least one neuroendocrine immunohistochemical marker ( 1 , 2 ). The extent of NED varies among cases and may influence clinical behavior and prognosis ( 3 ). PaNED should be distinguished from treatment-related neuroendocrine prostate carcinoma (t-NEPC) and de-novo pure neuroendocrine carcinomas (NEPCs). t-NEPC typically arises following androgen deprivation therapy (ADT) and is associated with aggressive clinical features, frequent loss of prostate-specific markers, and inactivation of tumor suppressors such as TP53 and RB1( 4 , 5 ). De novo pure NECs are rare but also highly aggressive, with distinct molecular and clinical characteristics ( 1 , 6 ). Despite increasing recognition of NED in prostate cancer, the clinicopathological and prognostic features of treatment-naïve PaNED remain poorly defined. In particular, the relationships between histomorphological features, programmed death-ligand 1 (PD-L1) expression, and clinical outcomes in this group are unclear. Clarifying these associations may improve diagnostic accuracy, risk stratification, and therapeutic decision-making. This study aimed to investigate the associations between histomorphological findings, PD-L1 expression, and prognostic parameters in a cohort of treatment-naïve patients with PaNED. MATERIALS AND METHODS Study Design and Ethical Approval This single-center, retrospective, observational study was conducted in accordance with the Declaration of Helsinki and was approved by the Umraniye Training and Research Hospital Ethics Committee, University of Health Sciences, Istanbul, Turkey (approval number: B.10.1.TKH.4.34.H.GP.0.01/179). The requirement for written informed consent to participate was waived by the ethics committee due to the retrospective design of the study and the use of anonymized archival data. The study was reported in compliance with the STROBE guidelines for cohort studies. Case selection Seventeen cases of treatment-naïve PaNED diagnosed between June 2014 and June 2024 were included in the study. Patients who had received prior therapy, had missing follow-up data, or had insufficient tissue for immunohistochemistry were excluded. Demographic and clinical data were retrieved from the hospital database. Histopathological and Immunohistochemical Evaluation All hematoxylin and eosin (H&E)-stained slides and immunohistochemical preparations were independently reviewed by two pathologists. PaNED was defined using morphological and immunohistochemical criteria. The extent of NED was calculated as the ratio of the NED area to the total tumor area. According to recent literature, a 30% threshold is commonly used to define mixed neuroendocrine-non-neuroendocrine neoplasms (MiNENs), particularly in colorectal tumors ( 7 ). Based on this, we classified cases with less than 30% NED as “focal”, and those with 30% or more as “diffuse”. Immunohistochemical evaluation of synaptophysin (clone SY38, 1:100 dilution, Ventana Medical Systems, Tucson, AZ, USA) was performed on archived slides, with staining intensity scored (SIS) as weak (1+), moderate (2+), or strong (3+). Chromogranin A staining was assessed in five cases to support NED diagnosis. PD-L1 (clone 22C3, 1:50 dilution; Leica Biosystems, Newcastle, UK) immunohistochemistry was performed using a standardized protocol. Only membranous staining in tumor cells was considered positive, while both membranous and cytoplasmic staining were assessed in immune cells; necrotic areas were excluded. Tumor Proportion Score (TPS) was defined as the percentage of tumor cells with membranous PD-L1 staining (≥ 1% positive). Combined Positive Score (CPS) was calculated as the ratio of PD-L1–positive tumor and immune cells to total viable tumor cells, with CPS ≥ 10 considered positive. Statistical Analysis All statistical analyses were performed using IBM SPSS Statistics for Mac (version 27.0, IBM Corp., Armonk, NY, USA) . Normality was assessed with the Shapiro-Wilk test and histograms. Categorical variables were reported as counts and percentages; continuous variables as median (IQR) or mean ± SD. Due to small sample size, non-parametric tests were used; Fisher’s exact test for categorical variables, Mann-Whitney U test for continuous variables, and Spearman’s rank correlation for SIS and PD-L1 CPS. Overall survival (OS) was calculated from surgery to death or last follow-up, with Kaplan-Meier curves and log-rank test for group comparisons. Two-tailed p-values < 0.05 were considered significant. RESULTS Patient Characteristics and Histological Findings The mean age of the cohort was 65.2 ± 6.6 years. Radical prostatectomy was performed in 58.8% of patients, and Grade Group 5 (GG5) was observed in 47.1%. The mean percentage of NED was 42.6 ± 24.5% (range, 10–80%), with diffuse NED present in 70.6% of cases. SIS was weak in 17.6%, moderate in 47.1%, and strong in 35.3% of cases. Representative sections of NED and SIS are shown in Fig. 1 . PD-L1 TPS positivity was found in 17.6% of cases, and CPS positivity in 35.3% (Fig. 2 ). During a mean follow-up of 55.2 ± 33 months, metastatic disease was present in 41.2% of patients, and the overall mortality rate was 29.4%. Detailed demographic and clinicopathological characteristics are presented in Table 1 . Table 1 Demographic and Clinicopathological Characteristics Specimen type, n (%) RRP 10 (58.8) TRUS 6 (35.3) TUR 1 (5.9) Age (mean ± SD), years 65.2 ± 6.6 Tumor volume (%) (median, IQR) 33.5 (30.2) Preoperative PSA (ng/mL) (median, IQR) 11.5 (47.5) GG, n (%) GG2 1 (5.9) GG3 4 (23.5) GG4 4 (23.5) GG5 8 (47.1) Lymphovascular invasion, n (%) 6 (35.3) Perineural invasion, n (%) 12 (70.6) NED, n(%) focal 5 (29.4) diffuse 12 (70.6) SIS, n(%) weak 3 (17.6) moderate 8 (47.1) strong 6 (35.3) Metastasis, n (%) 7 (41.2) Follow-up duration (months, mean ± SD) 55.2 ± 33 Death during follow-up, n (%) 5 (29.4) Abbreviations : RRP: Robotic Radical prostatectomy, TRUS: Transrectal ultrasound-guided biopsy, TUR: Transurethral resection, SD: Standard deviation, IQR: Interquartile range, PSA: Prostate-specific antigen, GG: Grade group, NED: Neuroendocrine differentiaton, SIS: Synaptophysin intensity score. Association of SIS and NED with PD-L1 Expression The relationships between SIS, NED extent, and PD-L1 expression are summarized in Table 2 . No significant differences were found between SIS groups regarding PD-L1 TPS or CPS positivity. There was a moderate negative correlation trend between SIS and PD-L1 CPS (Spearman’s rho = -0.481, p = 0.051), with lower CPS values observed in cases with strong synaptophysin staining. The extent and percentage of NED were not significantly associated with PD-L1 status or other histomorphological parameters. Table 2 Association of SIS and NED with PD-L1 expression PD-L1 TPS PD-L1 TPS (%) PD-L1 CPS PD-L1 CPS (value) Positive n(%) p Mean ± SD p Positive n(%) p Mean ± SD p SIS 0.241¹ 0.175 2 0.071¹ 0.087 2 0.051 3 weak 0 (0.0) 0 (0.0) 2 (33.3) 15 ± 5 moderate 3 (100) 3.33 ± 1.25 4 (66.7) 31.25 ± 20.12 strong 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) NED 1.000 4 0.676 5 1.000 5 0.982 5 focal 1 (33.3) 5 2 (33.3) 30 ± 10 diffuse 2 (66.7) 2.5 ± 0.5 4 (66.7) 23.75 ± 21.05 ¹ Fisher-Freeman-Halton exact, ² Kruskal- Wallis H , 3 Spearman correlation , 4 Fisher’s exact , 5 Mann- Whitney U Abbreviations : SIS: Synaptophysin intensity score, NED: Neuroendocrine differentiation, TPS: tumor proportion score, CPS: combined positive score, SD: Standard deviation Association of clinicopathological parameters with PD-L1 expression The relationship between other clinicopathological parameters and PD-L1 expression was examined. No statistically significant association was found between grade group, tumor volume, PD-L1 TPS or CPS positivity, TPS percentage, or CPS value. Prognostic Parameters and Survival Analysis No significant associations were found between NED group, SIS, PD-L1 TPS or CPS positivity, and presence of metastasis (p = 0.338, 0.377, 1.000, and 1.000, respectively). Similarly, PD-L1 TPS percentage and CPS value were not significantly related to metastasis (p = 0.691 and 0.280). Lymphovascular invasion (LVI) and perineural invasion (PNI) also showed no significant associations with NED group, SIS, or PD-L1 status. OS was analyzed by SIS, NED, and PD-L1 expression using Kaplan–Meier and log-rank tests. Survival differed significantly between SIS groups (p = 0.031); five-year survival rates were 100% (weak), 87.5% (moderate), and 33.3% (strong). Median survival in the strong-staining group was 26 months, while median survival was not reached in the other groups. Mean survival times for focal and diffuse NED groups were similar (85.4 vs. 84.8 months; p = 0.463) (Fig. 3 A– 3 B). Survival was compared between PD-L1 TPS and CPS positive and negative groups. No significant differences were found (p = 0.841 for TPS, p = 0.540 for CPS) (Fig. 3 C– 3 D). Mean survival times were 92.0 months (TPS-negative) vs. 63.7 months (TPS-positive), and 85.9 months (CPS-negative) vs. 78.3 months (CPS-positive). DISCUSSION This study examined the relationship between NED, SIS, and PD-L1 expression in treatment-naïve PaNED. While NED extent was not linked to adverse pathology or survival, strong SIS was associated with poorer OS. PD-L1 expression was generally low and not significantly related to outcomes, though a trend toward moderate negative correlation with SIS was noted. These findings indicate a complex relationship between neuroendocrine features and immune checkpoint expression, warranting further research. PaNED is relatively understudied, and its biological and clinical significance remains unclear ( 8 ). The clinicopathological and prognostic roles of NED and immune checkpoint expression in treatment-naïve prostatic adenocarcinoma are not well defined. While t-NEPC or de novo NEPC are linked to aggressive disease and poor prognosis ( 9 , 10 ), most studies report that neuroendocrine features in conventional prostatic adenocarcinoma do not independently predict outcomes ( 11 ). The prognostic value of NED extent in prostatic adenocarcinoma is controversial. Some studies link diffuse NED to more aggressive behavior, while others find no outcome differences between focal and diffuse patterns ( 12 , 13 ). Prognosis may depend more on molecular alterations, such as RB1 and TP53 loss, than on NED extent alone ( 14 ). In our cohort, NED extent was not associated with adverse pathology or survival, suggesting it is not a reliable prognostic factor. Additionally, no standard cutoff distinguishes focal from diffuse NED in prostate cancer. Our results indicate that synaptophysin intensity, rather than NED extent, is a more relevant prognostic factor. This is consistent with recent studies showing that high neuroendocrine marker intensity correlates with worse outcomes ( 12 , 15 , 16 ). Strong synaptophysin expression is also linked to aggressive behavior and shorter OS in t-NEPC and de novo NEPC ( 9 , 10 , 17 ). The prognostic or predictive value of PD-L1 in prostate cancer remains unclear. In our study, PD-L1 expression (TPS and CPS) was low and did not correlate with OS or adverse pathology, consistent with previous reports showing minimal PD-L1 expression in prostate cancer ( 18 , 19 ). Thus, PD-L1 is not a reliable biomarker for immunotherapy selection in this setting ( 20 ). The immune microenvironment in PaNED is heterogeneous, and the relationship between PD-L1 and synaptophysin intensity is unclear. Although we observed a trend toward lower PD-L1 CPS in cases with strong synaptophysin staining, this was not statistically significant, likely reflecting the complex tumor microenvironment and limitations of current scoring methods ( 21 – 23 ). Our findings suggest two main clinical implications. First, assessing synaptophysin intensity in neuroendocrine areas may help identify patients at higher risk of poor outcomes ( 9 , 17 ). Second, the consistently low PD-L1 expression observed in our cohort further supports the limited utility of PD-L1 as a biomarker for immunotherapy selection in prostate cancer, in contrast to its established role in other solid tumors ( 19 ). Thus, risk stratification in PaNED should include qualitative, molecular, and immunophenotypic features, not just quantitative measures ( 24 ). Limitations of this study include the small sample size, single-center retrospective design, and absence of molecular profiling or RB1/TP53 assessment, all of which may limit generalizability and risk stratification. Additionally, reliance on a single neuroendocrine marker may not fully capture the heterogeneity of NED. A key strength of this study is the exclusive inclusion of treatment-naïve cases, which provides clearer insight into intrinsic tumor biology. Furthermore, the integration of clinicopathological, immunophenotypic, and survival data enhances the robustness of the prognostic analysis ( 25 ). CONCLUSION This study demonstrates the heterogeneity of NED in treatment-naïve prostatic adenocarcinoma. While NED extent does not predict outcomes, strong synaptophysin expression is linked to poorer survival, highlighting the value of qualitative neuroendocrine assessment. The negative correlation between SIS and PD-L1 CPS suggests higher neuroendocrine marker expression may be associated with lower immune checkpoint activity. These results support integrated diagnostic and prognostic strategies combining immunophenotypic, molecular, and clinical data in PaNED. SUMMARY In prostate cancer with neuroendocrine features, strong synaptophysin staining is linked to shorter survival. Assessing this marker may help identify patients at higher risk and guide more effective treatment choices. Abbreviations ADT Androgen deprivation therapy CPS Combined positive score GG Grade group H&E Hematoxylin and eosin IQR Interquartile range LVI Lymphovascular invasion MiNEN Mixed neuroendocrine-non-neuroendocrine neoplasm NED Neuroendocrine differentiation NEPC Neuroendocrine prostate carcinoma OS Overall survival PaNED Prostatic adenocarcinoma with neuroendocrine differentiation PD-L1 Programmed death-ligand 1 PNI Perineural invasion PSA Prostate-specific antigen RRP Robotic radical prostatectomy SD Standard deviation SIS Synaptophysin intensity score STROBE Strengthening the Reporting of Observational Studies in Epidemiology TPS Tumor proportion score TRUS Transrectal ultrasound-guided biopsy TUR Transurethral resection. Declarations Ethics approval and consent to participate The study protocol was approved by the Umraniye Training and Research Hospital Ethics Committee, University of Health Sciences, Istanbul, Turkey (approval number: B.10.1.TKH.4.34.H.GP.0.01/179). Given the retrospective design of the study and the use of anonymized archival data, the requirement for written informed consent to participate was waived by the ethics committee. Consent for publication Not applicable. Competing interests The authors declare that they have no competing interests. Funding This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Author Contribution IT conceived and designed the study, performed the histopathological evaluation, collected clinicopathological data, and drafted the manuscript. OS contributed to the pathological review and data collection. IGB contributed to the pathological assessment and interpretation of immunohistochemical findings. NMS collected and interpreted the urological and clinical data. MO contributed to the acquisition and interpretation of oncological data. All authors contributed to data interpretation, critically revised the manuscript for important intellectual content, and approved the final version of the manuscript. Acknowledgements None. Data Availability The datasets generated and/or analysed during the current study are not publicly available due to institutional and national data protection regulations but are available from the corresponding author on reasonable request. References Greco F, Domanico L, Inferrera A, Gozo M, Lembo F. Neuroendocrine prostate tumors: histologic features and therapy. Uro-Technol J. 2023;7(3):18–25. Abdulfatah E, Reichert ZR, Davenport MS, Chinnaiyan AM, Dadhania V, Wang X, et al. De novo neuroendocrine transdifferentiation in primary prostate cancer-a phenotype associated with advanced clinico-pathologic features and aggressive outcome. Med Oncol Northwood Lond Engl. 2021;38(3):26. Fine SW. Neuroendocrine tumors of the prostate. Mod Pathol Off J U S Can Acad Pathol Inc. 2018;31(S1):S122–132. 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08:48:24","extension":"jpeg","order_by":4,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":943791,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8180352/v1/07296851cd8654b92619cf48.jpeg"},{"id":98746826,"identity":"90e046c4-a06a-4b8c-ac38-2775c8490c4d","added_by":"auto","created_at":"2025-12-22 08:48:24","extension":"jpeg","order_by":5,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":314248,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8180352/v1/37b5a34d19f6f65c2961db1c.jpeg"},{"id":98779255,"identity":"fb902694-4890-4f84-99e0-16516d0f09c1","added_by":"auto","created_at":"2025-12-22 12:30:06","extension":"xml","order_by":9,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":81412,"visible":true,"origin":"","legend":"","description":"","filename":"7d20a2b3955346b7848f8f42a53830bf1structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-8180352/v1/611e226e8c34d208d991539a.xml"},{"id":98746834,"identity":"e87f5efe-304f-41ff-b1ee-c0f896251d16","added_by":"auto","created_at":"2025-12-22 08:48:24","extension":"html","order_by":10,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":92758,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-8180352/v1/2817612f8b64af5ddeb2a7ef.html"},{"id":98746829,"identity":"f335c513-0456-4583-9856-649893fe8d9b","added_by":"auto","created_at":"2025-12-22 08:48:24","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":409306,"visible":true,"origin":"","legend":"\u003cp\u003eRepresentative images of NED and synaptophysin intensity in PaNED. (A) Focal NED, 100x. (B-C) Diffuse NED, 400x. (D) Weak synaptophysin intensity (SIS 1+), 400x. (E) Moderate synaptophysin intensity (SIS 2+), 400x. (F) Strong synaptophysin intensity (SIS 3+), 400x.\u003c/p\u003e","description":"","filename":"Onlinefloatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-8180352/v1/2e8d9d9fc2965f97b38a7ce0.png"},{"id":98746833,"identity":"9f80fad4-fa2b-427c-ab47-8ab2bf3ccb8a","added_by":"auto","created_at":"2025-12-22 08:48:24","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":344541,"visible":true,"origin":"","legend":"\u003cp\u003ePD-L1 expression in PaNED. \u003cstrong\u003e(A)\u003c/strong\u003e TPS positivity, 400x. \u003cstrong\u003e(B)\u003c/strong\u003e CPS positivity, 400x.\u003c/p\u003e","description":"","filename":"Onlinefloatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-8180352/v1/5b31f30dc7af311ea71e3dc1.png"},{"id":98746823,"identity":"2d356d1f-e864-4a43-9c76-6da68dc8e3fa","added_by":"auto","created_at":"2025-12-22 08:48:24","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":64503,"visible":true,"origin":"","legend":"\u003cp\u003eKaplan-Meier survival curves for OS in PaNED. (A) OS by SIS; patients with strong synaptophysin expression had significantly shorter OS than those with weak or moderate expression (p = 0.031). (B) OS according to the extent of NED (focal vs. diffuse); no significant difference was observed. (C) OS by TPS status; no significant difference was observed. (D) OS by CPS status; no significant difference was observed.\u003c/p\u003e","description":"","filename":"Onlinefloatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-8180352/v1/8770229a1fc6922bb38b03b3.png"},{"id":100616319,"identity":"8ace7433-e4f3-4bac-a2c1-33b60b8a1d8e","added_by":"auto","created_at":"2026-01-19 17:42:24","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1873915,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8180352/v1/eb925f2b-cb69-43bf-809e-6c54f01f1fd4.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Neuroendocrine differentiation and PD-L1 expression in treatment-naïve prostatic adenocarcinoma: Clinicopathological correlates and prognostic significance","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eProstatic adenocarcinoma with neuroendocrine differentiation (PaNED) is characterized by conventional adenocarcinoma cells exhibiting neuroendocrine features, such as round to oval nuclei, finely granular chromatin, and scant to moderate eosinophilic cytoplasm. These tumors often display nested, trabecular, rosette-like, or solid growth patterns. The diagnosis of NED relies on these histological features and the expression of at least one neuroendocrine immunohistochemical marker (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). The extent of NED varies among cases and may influence clinical behavior and prognosis (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003ePaNED should be distinguished from treatment-related neuroendocrine prostate carcinoma (t-NEPC) and de-novo pure neuroendocrine carcinomas (NEPCs). t-NEPC typically arises following androgen deprivation therapy (ADT) and is associated with aggressive clinical features, frequent loss of prostate-specific markers, and inactivation of tumor suppressors such as TP53 and RB1(\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e). De novo pure NECs are rare but also highly aggressive, with distinct molecular and clinical characteristics (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eDespite increasing recognition of NED in prostate cancer, the clinicopathological and prognostic features of treatment-na\u0026iuml;ve PaNED remain poorly defined. In particular, the relationships between histomorphological features, programmed death-ligand 1 (PD-L1) expression, and clinical outcomes in this group are unclear. Clarifying these associations may improve diagnostic accuracy, risk stratification, and therapeutic decision-making.\u003c/p\u003e \u003cp\u003eThis study aimed to investigate the associations between histomorphological findings, PD-L1 expression, and prognostic parameters in a cohort of treatment-na\u0026iuml;ve patients with PaNED.\u003c/p\u003e"},{"header":"MATERIALS AND METHODS","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy Design and Ethical Approval\u003c/h2\u003e \u003cp\u003e This single-center, retrospective, observational study was conducted in accordance with the Declaration of Helsinki and was approved by the Umraniye Training and Research Hospital Ethics Committee, University of Health Sciences, Istanbul, Turkey (approval number: B.10.1.TKH.4.34.H.GP.0.01/179). The requirement for written informed consent to participate was waived by the ethics committee due to the retrospective design of the study and the use of anonymized archival data. The study was reported in compliance with the STROBE guidelines for cohort studies.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eCase selection\u003c/h3\u003e\n\u003cp\u003eSeventeen cases of treatment-na\u0026iuml;ve PaNED diagnosed between June 2014 and June 2024 were included in the study. Patients who had received prior therapy, had missing follow-up data, or had insufficient tissue for immunohistochemistry were excluded. Demographic and clinical data were retrieved from the hospital database.\u003c/p\u003e\n\u003ch3\u003eHistopathological and Immunohistochemical Evaluation\u003c/h3\u003e\n\u003cp\u003eAll hematoxylin and eosin (H\u0026amp;E)-stained slides and immunohistochemical preparations were independently reviewed by two pathologists. PaNED was defined using morphological and immunohistochemical criteria. The extent of NED was calculated as the ratio of the NED area to the total tumor area. According to recent literature, a 30% threshold is commonly used to define mixed neuroendocrine-non-neuroendocrine neoplasms (MiNENs), particularly in colorectal tumors (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e). Based on this, we classified cases with less than 30% NED as \u0026ldquo;focal\u0026rdquo;, and those with 30% or more as \u0026ldquo;diffuse\u0026rdquo;.\u003c/p\u003e \u003cp\u003eImmunohistochemical evaluation of synaptophysin (clone SY38, 1:100 dilution, Ventana Medical Systems, Tucson, AZ, USA) was performed on archived slides, with staining intensity scored (SIS) as weak (1+), moderate (2+), or strong (3+). Chromogranin A staining was assessed in five cases to support NED diagnosis. PD-L1 (clone 22C3, 1:50 dilution; Leica Biosystems, Newcastle, UK) immunohistochemistry was performed using a standardized protocol. Only membranous staining in tumor cells was considered positive, while both membranous and cytoplasmic staining were assessed in immune cells; necrotic areas were excluded. Tumor Proportion Score (TPS) was defined as the percentage of tumor cells with membranous PD-L1 staining (\u0026ge;\u0026thinsp;1% positive). Combined Positive Score (CPS) was calculated as the ratio of PD-L1\u0026ndash;positive tumor and immune cells to total viable tumor cells, with CPS\u0026thinsp;\u0026ge;\u0026thinsp;10 considered positive.\u003c/p\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eStatistical Analysis\u003c/h2\u003e \u003cp\u003eAll statistical analyses were performed using \u003cem\u003eIBM SPSS Statistics for Mac (version 27.0, IBM Corp., Armonk, NY, USA)\u003c/em\u003e. Normality was assessed with the Shapiro-Wilk test and histograms. Categorical variables were reported as counts and percentages; continuous variables as median (IQR) or mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD. Due to small sample size, non-parametric tests were used; Fisher\u0026rsquo;s exact test for categorical variables, Mann-Whitney U test for continuous variables, and Spearman\u0026rsquo;s rank correlation for SIS and PD-L1 CPS. Overall survival (OS) was calculated from surgery to death or last follow-up, with Kaplan-Meier curves and log-rank test for group comparisons. Two-tailed p-values\u0026thinsp;\u0026lt;\u0026thinsp;0.05 were considered significant.\u003c/p\u003e \u003c/div\u003e"},{"header":"RESULTS","content":"\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003ePatient Characteristics and Histological Findings\u003c/h2\u003e \u003cp\u003eThe mean age of the cohort was 65.2\u0026thinsp;\u0026plusmn;\u0026thinsp;6.6 years. Radical prostatectomy was performed in 58.8% of patients, and Grade Group 5 (GG5) was observed in 47.1%. The mean percentage of NED was 42.6\u0026thinsp;\u0026plusmn;\u0026thinsp;24.5% (range, 10\u0026ndash;80%), with diffuse NED present in 70.6% of cases. SIS was weak in 17.6%, moderate in 47.1%, and strong in 35.3% of cases. Representative sections of NED and SIS are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. PD-L1 TPS positivity was found in 17.6% of cases, and CPS positivity in 35.3% (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eDuring a mean follow-up of 55.2\u0026thinsp;\u0026plusmn;\u0026thinsp;33 months, metastatic disease was present in 41.2% of patients, and the overall mortality rate was 29.4%. Detailed demographic and clinicopathological characteristics are presented in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eDemographic and Clinicopathological Characteristics\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"2\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSpecimen type, n (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eRRP\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e10 (58.8)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eTRUS\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e6 (35.3)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eTUR\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1 (5.9)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAge (mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD), years\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e65.2\u0026thinsp;\u0026plusmn;\u0026thinsp;6.6\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eTumor volume (%) (median, IQR)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e33.5 (30.2)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePreoperative PSA (ng/mL) (median, IQR)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e11.5 (47.5)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eGG, n (%)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eGG2\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1 (5.9)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eGG3\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e4 (23.5)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eGG4\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e4 (23.5)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eGG5\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e8 (47.1)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eLymphovascular invasion, n (%)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e6 (35.3)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePerineural invasion, n (%)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e12 (70.6)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eNED, n(%)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003efocal\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e5 (29.4)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003ediffuse\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e12 (70.6)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSIS, n(%)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eweak\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e3 (17.6)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003emoderate\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e8 (47.1)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003estrong\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e6 (35.3)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMetastasis, n (%)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e7 (41.2)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eFollow-up duration (months, mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e55.2\u0026thinsp;\u0026plusmn;\u0026thinsp;33\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eDeath during follow-up, n (%)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e5 (29.4)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"2\"\u003e\u003cb\u003eAbbreviations\u003c/b\u003e: \u003cem\u003eRRP: Robotic Radical prostatectomy, TRUS: Transrectal ultrasound-guided biopsy, TUR: Transurethral resection, SD: Standard deviation, IQR: Interquartile range, PSA: Prostate-specific antigen, GG: Grade group, NED: Neuroendocrine differentiaton, SIS: Synaptophysin intensity score.\u003c/em\u003e\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eAssociation of SIS and NED with PD-L1 Expression\u003c/h3\u003e\n\u003cp\u003eThe relationships between SIS, NED extent, and PD-L1 expression are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. No significant differences were found between SIS groups regarding PD-L1 TPS or CPS positivity. There was a moderate negative correlation trend between SIS and PD-L1 CPS (Spearman\u0026rsquo;s rho = -0.481, p\u0026thinsp;=\u0026thinsp;0.051), with lower CPS values observed in cases with strong synaptophysin staining. The extent and percentage of NED were not significantly associated with PD-L1 status or other histomorphological parameters.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eAssociation of SIS and NED with PD-L1 expression\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"9\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003ePD-L1 TPS\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003ePD-L1 TPS (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003ePD-L1 CPS\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e \u003cp\u003ePD-L1 CPS (value)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003ePositive\u003c/em\u003e\u003c/p\u003e \u003cp\u003e\u003cem\u003en(%)\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003ep\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003ep\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cem\u003ePositive\u003c/em\u003e\u003c/p\u003e \u003cp\u003e\u003cem\u003en(%)\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cem\u003ep\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u003cem\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003e\u003cem\u003ep\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSIS\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.241\u0026sup1;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.175\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.071\u0026sup1;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.087\u003csup\u003e2\u003c/sup\u003e 0.051\u003csup\u003e3\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eweak\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0 (0.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0 (0.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2 (33.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e15\u0026thinsp;\u0026plusmn;\u0026thinsp;5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003emoderate\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3 (100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3.33\u0026thinsp;\u0026plusmn;\u0026thinsp;1.25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e4 (66.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e31.25\u0026thinsp;\u0026plusmn;\u0026thinsp;20.12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003estrong\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0 (0.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0 (0.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0 (0.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0 (0.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eNED\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.000\u003csup\u003e4\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.676\u003csup\u003e5\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e1.000\u003csup\u003e5\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.982\u003csup\u003e5\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003efocal\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1 (33.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2 (33.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e30\u0026thinsp;\u0026plusmn;\u0026thinsp;10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003ediffuse\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2 (66.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.5\u0026thinsp;\u0026plusmn;\u0026thinsp;0.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e4 (66.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e23.75\u0026thinsp;\u0026plusmn;\u0026thinsp;21.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"9\" nameend=\"c9\" namest=\"c1\"\u003e \u003cp\u003e\u003cem\u003e\u0026sup1; Fisher-Freeman-Halton exact, \u0026sup2; Kruskal- Wallis H\u003c/em\u003e, \u003csup\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sup\u003e \u003cem\u003eSpearman correlation\u003c/em\u003e, \u003csup\u003e\u003cem\u003e4\u003c/em\u003e\u003c/sup\u003e \u003cem\u003eFisher\u0026rsquo;s exact\u003c/em\u003e, \u003csup\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sup\u003e \u003cem\u003eMann- Whitney U\u003c/em\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003eAbbreviations\u003c/b\u003e: \u003cem\u003eSIS: Synaptophysin intensity score, NED: Neuroendocrine differentiation, TPS: tumor proportion score, CPS: combined positive score, SD: Standard deviation\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e\n\u003ch3\u003eAssociation of clinicopathological parameters with PD-L1 expression\u003c/h3\u003e\n\u003cp\u003eThe relationship between other clinicopathological parameters and PD-L1 expression was examined. No statistically significant association was found between grade group, tumor volume, PD-L1 TPS or CPS positivity, TPS percentage, or CPS value.\u003c/p\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003ePrognostic Parameters and Survival Analysis\u003c/h2\u003e \u003cp\u003eNo significant associations were found between NED group, SIS, PD-L1 TPS or CPS positivity, and presence of metastasis (p\u0026thinsp;=\u0026thinsp;0.338, 0.377, 1.000, and 1.000, respectively). Similarly, PD-L1 TPS percentage and CPS value were not significantly related to metastasis (p\u0026thinsp;=\u0026thinsp;0.691 and 0.280). Lymphovascular invasion (LVI) and perineural invasion (PNI) also showed no significant associations with NED group, SIS, or PD-L1 status.\u003c/p\u003e \u003cp\u003eOS was analyzed by SIS, NED, and PD-L1 expression using Kaplan\u0026ndash;Meier and log-rank tests. Survival differed significantly between SIS groups (p\u0026thinsp;=\u0026thinsp;0.031); five-year survival rates were 100% (weak), 87.5% (moderate), and 33.3% (strong). Median survival in the strong-staining group was 26 months, while median survival was not reached in the other groups. Mean survival times for focal and diffuse NED groups were similar (85.4 vs. 84.8 months; p\u0026thinsp;=\u0026thinsp;0.463) (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eA\u0026ndash;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eB).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eSurvival was compared between PD-L1 TPS and CPS positive and negative groups. No significant differences were found (p\u0026thinsp;=\u0026thinsp;0.841 for TPS, p\u0026thinsp;=\u0026thinsp;0.540 for CPS) (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eC\u0026ndash;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eD). Mean survival times were 92.0 months (TPS-negative) vs. 63.7 months (TPS-positive), and 85.9 months (CPS-negative) vs. 78.3 months (CPS-positive).\u003c/p\u003e \u003c/div\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eThis study examined the relationship between NED, SIS, and PD-L1 expression in treatment-na\u0026iuml;ve PaNED. While NED extent was not linked to adverse pathology or survival, strong SIS was associated with poorer OS. PD-L1 expression was generally low and not significantly related to outcomes, though a trend toward moderate negative correlation with SIS was noted. These findings indicate a complex relationship between neuroendocrine features and immune checkpoint expression, warranting further research.\u003c/p\u003e \u003cp\u003ePaNED is relatively understudied, and its biological and clinical significance remains unclear (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e). The clinicopathological and prognostic roles of NED and immune checkpoint expression in treatment-na\u0026iuml;ve prostatic adenocarcinoma are not well defined. While t-NEPC or de novo NEPC are linked to aggressive disease and poor prognosis (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e), most studies report that neuroendocrine features in conventional prostatic adenocarcinoma do not independently predict outcomes (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe prognostic value of NED extent in prostatic adenocarcinoma is controversial. Some studies link diffuse NED to more aggressive behavior, while others find no outcome differences between focal and diffuse patterns (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e). Prognosis may depend more on molecular alterations, such as RB1 and TP53 loss, than on NED extent alone (\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e). In our cohort, NED extent was not associated with adverse pathology or survival, suggesting it is not a reliable prognostic factor. Additionally, no standard cutoff distinguishes focal from diffuse NED in prostate cancer.\u003c/p\u003e \u003cp\u003eOur results indicate that synaptophysin intensity, rather than NED extent, is a more relevant prognostic factor. This is consistent with recent studies showing that high neuroendocrine marker intensity correlates with worse outcomes (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e). Strong synaptophysin expression is also linked to aggressive behavior and shorter OS in t-NEPC and de novo NEPC (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe prognostic or predictive value of PD-L1 in prostate cancer remains unclear. In our study, PD-L1 expression (TPS and CPS) was low and did not correlate with OS or adverse pathology, consistent with previous reports showing minimal PD-L1 expression in prostate cancer (\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e). Thus, PD-L1 is not a reliable biomarker for immunotherapy selection in this setting (\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e). The immune microenvironment in PaNED is heterogeneous, and the relationship between PD-L1 and synaptophysin intensity is unclear. Although we observed a trend toward lower PD-L1 CPS in cases with strong synaptophysin staining, this was not statistically significant, likely reflecting the complex tumor microenvironment and limitations of current scoring methods (\u003cspan additionalcitationids=\"CR22\" citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eOur findings suggest two main clinical implications. First, assessing synaptophysin intensity in neuroendocrine areas may help identify patients at higher risk of poor outcomes (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e). Second, the consistently low PD-L1 expression observed in our cohort further supports the limited utility of PD-L1 as a biomarker for immunotherapy selection in prostate cancer, in contrast to its established role in other solid tumors (\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e). Thus, risk stratification in PaNED should include qualitative, molecular, and immunophenotypic features, not just quantitative measures (\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eLimitations of this study include the small sample size, single-center retrospective design, and absence of molecular profiling or RB1/TP53 assessment, all of which may limit generalizability and risk stratification. Additionally, reliance on a single neuroendocrine marker may not fully capture the heterogeneity of NED. A key strength of this study is the exclusive inclusion of treatment-na\u0026iuml;ve cases, which provides clearer insight into intrinsic tumor biology. Furthermore, the integration of clinicopathological, immunophenotypic, and survival data enhances the robustness of the prognostic analysis (\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e).\u003c/p\u003e"},{"header":"CONCLUSION","content":"\u003cp\u003eThis study demonstrates the heterogeneity of NED in treatment-na\u0026iuml;ve prostatic adenocarcinoma. While NED extent does not predict outcomes, strong synaptophysin expression is linked to poorer survival, highlighting the value of qualitative neuroendocrine assessment. The negative correlation between SIS and PD-L1 CPS suggests higher neuroendocrine marker expression may be associated with lower immune checkpoint activity. These results support integrated diagnostic and prognostic strategies combining immunophenotypic, molecular, and clinical data in PaNED.\u003c/p\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eSUMMARY\u003c/h2\u003e \u003cp\u003eIn prostate cancer with neuroendocrine features, strong synaptophysin staining is linked to shorter survival. Assessing this marker may help identify patients at higher risk and guide more effective treatment choices.\u003c/p\u003e \u003c/div\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eADT\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eAndrogen deprivation therapy\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eCPS\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eCombined positive score\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eGG\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eGrade group\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eH\u0026amp;E\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eHematoxylin and eosin\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eIQR\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eInterquartile range\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eLVI\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eLymphovascular invasion\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eMiNEN\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eMixed neuroendocrine-non-neuroendocrine neoplasm\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eNED\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eNeuroendocrine differentiation\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eNEPC\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eNeuroendocrine prostate carcinoma\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eOS\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eOverall survival\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003ePaNED\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eProstatic adenocarcinoma with neuroendocrine differentiation\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003ePD-L1\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eProgrammed death-ligand 1\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003ePNI\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003ePerineural invasion\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003ePSA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eProstate-specific antigen\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eRRP\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eRobotic radical prostatectomy\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eSD\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eStandard deviation\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eSIS\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eSynaptophysin intensity score\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eSTROBE\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eStrengthening the Reporting of Observational Studies in Epidemiology\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eTPS\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eTumor proportion score\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eTRUS\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eTransrectal ultrasound-guided biopsy\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eTUR\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eTransurethral resection.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eEthics approval and consent to participate\u003c/h2\u003e \u003cp\u003e The study protocol was approved by the Umraniye Training and Research Hospital Ethics Committee, University of Health Sciences, Istanbul, Turkey (approval number: B.10.1.TKH.4.34.H.GP.0.01/179). Given the retrospective design of the study and the use of anonymized archival data, the requirement for written informed consent to participate was waived by the ethics committee.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eConsent for publication\u003c/strong\u003e \u003cp\u003eNot applicable.\u003c/p\u003e \u003c/p\u003e\u003cp\u003e \u003ch2\u003eCompeting interests\u003c/h2\u003e \u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eThis research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eIT conceived and designed the study, performed the histopathological evaluation, collected clinicopathological data, and drafted the manuscript. OS contributed to the pathological review and data collection. IGB contributed to the pathological assessment and interpretation of immunohistochemical findings. NMS collected and interpreted the urological and clinical data. MO contributed to the acquisition and interpretation of oncological data. All authors contributed to data interpretation, critically revised the manuscript for important intellectual content, and approved the final version of the manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgements\u003c/h2\u003e \u003cp\u003eNone.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe datasets generated and/or analysed during the current study are not publicly available due to institutional and national data protection regulations but are available from the corresponding author on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eGreco F, Domanico L, Inferrera A, Gozo M, Lembo F. Neuroendocrine prostate tumors: histologic features and therapy. Uro-Technol J. 2023;7(3):18\u0026ndash;25.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAbdulfatah E, Reichert ZR, Davenport MS, Chinnaiyan AM, Dadhania V, Wang X, et al. De novo neuroendocrine transdifferentiation in primary prostate cancer-a phenotype associated with advanced clinico-pathologic features and aggressive outcome. Med Oncol Northwood Lond Engl. 2021;38(3):26.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFine SW. Neuroendocrine tumors of the prostate. Mod Pathol Off J U S Can Acad Pathol Inc. 2018;31(S1):S122\u0026ndash;132.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLai JI, Peng YC, Chang PMH, Chang YH, Chung HJ, Huang YH, et al. Real-world experience in treatment outcome and genomic insights for metastatic prostate neuroendocrine carcinoma. J Chin Med Assoc. 2025;88(4):283.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWishahi M. Treatment-induced neuroendocrine prostate cancer and de novo neuroendocrine prostate cancer: Identification, prognosis and survival, genetic and epigenetic factors. World J Clin Cases. 2024;12(13):2143\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eUrban RQ, Keerthikumar S, Clark A, Wang H, Phipson B, Bakshi A et al. Defining focal neuroendocrine differentiation as a transcriptionally distinct form of prostate cancer pathology characterized by the expression of androgen receptors [Internet]. bioRxiv; 2024 [cited 2025 May 4]. p. 2024.03.17.585125. 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Virchows Arch Int J Pathol. 2012;461(2):103\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGenitsch V, Zlobec I, Seiler R, Thalmann GN, Fleischmann A. Neuroendocrine Differentiation in Metastatic Conventional Prostate Cancer Is Significantly Increased in Lymph Node Metastases Compared to the Primary Tumors. Int J Mol Sci. 2017;18(8):1640.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eParimi V, Goyal R, Poropatich K, Yang XJ. Neuroendocrine differentiation of prostate cancer: a review. Am J Clin Exp Urol. 2014;2(4):273\u0026ndash;85.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eUeki H, Jimbo N, Terakawa T, Hara T, Tobe T, Hirata J, et al. Evaluating RB1 and p53 as diagnostic markers in treatment-related neuroendocrine prostate cancer through immunohistochemistry and genomic analysis of RB1 and TP53. Prostate. 2024;84(16):1506\u0026ndash;14.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHuang Z, Tang Y, Wei Y, Qian J, Kang Y, Wang D, et al. Prognostic Significance of Chromogranin A Expression in the Initial and Second Biopsies in Metastatic Prostate Cancer. J Clin Med. 2023;12(10):3362.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKannan A, Clouston D, Frydenberg M, Ilic D, Karim MN, Evans SM, et al. Neuroendocrine cells in prostate cancer correlate with poor outcomes: a systematic review and meta-analysis. BJU Int. 2022;130(4):420\u0026ndash;33.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ede Kouchkovsky I, Chan E, Schloss C, Poehlein C, Aggarwal R. Diagnosis and management of neuroendocrine prostate cancer. Prostate. 2024;84(5):426\u0026ndash;40.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCalagua C, Russo J, Sun Y, Schaefer R, Lis R, Zhang Z, et al. Expression of PD-L1 in Hormone-na\u0026iuml;ve and Treated Prostate Cancer Patients Receiving Neoadjuvant Abiraterone Acetate plus Prednisone and Leuprolide. Clin Cancer Res Off J Am Assoc Cancer Res. 2017;23(22):6812\u0026ndash;22.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFankhauser CD, Sch\u0026uuml;ffler PJ, Gillessen S, Omlin A, Rupp NJ, Rueschoff JH, et al. Comprehensive immunohistochemical analysis of PD-L1 shows scarce expression in castration-resistant prostate cancer. Oncotarget. 2017;9(12):10284\u0026ndash;93.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSpetsieris N, Boukovala M, Patsakis G, Alafis I, Efstathiou E. Neuroendocrine and Aggressive-Variant Prostate Cancer. Cancers. 2020;12(12):3792.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNovysedlak R, Guney M, Al Khouri M, Bartolini R, Koumbas Foley L, Benesova I et al. The Immune Microenvironment in Prostate Cancer: A Comprehensive Review. Oncology. 2024;1\u0026ndash;25.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhuang X, Li H, You Z, Cheng H, Guo G, Chen X, et al. PD - L1 (SP263) expression correlates with pathological aggressive parameters in prostate cancer. Ann Diagn Pathol. 2025;78:152481.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePalicelli A, Bonacini M, Croci S, Magi-Galluzzi C, Ca\u0026ntilde;ete-Portillo S, Chaux A, et al. What Do We Have to Know about PD-L1 Expression in Prostate Cancer? A Systematic Literature Review. Part 1: Focus on Immunohistochemical Results with Discussion of Pre-Analytical and Interpretation Variables. Cells. 2021;10(11):3166.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAbida W, Cyrta J, Heller G, Prandi D, Armenia J, Coleman I, et al. Genomic correlates of clinical outcome in advanced prostate cancer. Proc Natl Acad Sci. 2019;116(23):11428\u0026ndash;36.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eEpstein JI, Amin MB, Beltran H, Lotan TL, Mosquera JM, Reuter VE, et al. Proposed morphologic classification of prostate cancer with neuroendocrine differentiation. Am J Surg Pathol. 2014;38(6):756\u0026ndash;67.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-urology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"buro","sideBox":"Learn more about [BMC Urology](http://bmcurol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/buro/default.aspx","title":"BMC Urology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Prostatic adenocarcinoma, Neuroendocrine differentiation, Synaptophysin, Programmed death-ligand 1 (PD-L1), Treatment-naïve, Prognosis","lastPublishedDoi":"10.21203/rs.3.rs-8180352/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8180352/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003ePurpose\u003c/h2\u003e \u003cp\u003eProstatic adenocarcinoma with neuroendocrine differentiation (PaNED) is distinct from treatment-related and de-novo neuroendocrine prostate carcinomas, yet remains under-investigated in treatment-na\u0026iuml;ve patients. This study aimed to evaluate the associations of NED extent, synaptophysin intensity score (SIS), and PD-L1 expression with other histomorphological features and prognosis in treatment-na\u0026iuml;ve PaNED.\u003c/p\u003e\u003ch2\u003eMaterials and Methods\u003c/h2\u003e \u003cp\u003eSeventeen patients with PaNED diagnosed between 2014 and 2024 were retrospectively analyzed. NED was classified as diffuse (\u0026ge;\u0026thinsp;30%) or focal (\u0026lt;\u0026thinsp;30%), and SIS was scored as weak (+\u0026thinsp;1), moderate (+\u0026thinsp;2), or strong (+\u0026thinsp;3). PD-L1 expression was assessed using tumor proportion score (TPS, cut-off \u0026ge;\u0026thinsp;1%) and combined positive score (CPS, cut-off \u0026ge;\u0026thinsp;10). Clinicopathological data and survival outcomes were evaluated.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eThe mean age was 65.2\u0026thinsp;\u0026plusmn;\u0026thinsp;6.6 years, and 47.1% (n\u0026thinsp;=\u0026thinsp;8) of the cases were Grade Group 5. Diffuse NED was observed in 70.6% of cases, and strong synaptophysin expression in 35.3%. PD-L1 TPS and CPS positivity were detected in 17.6% and 35.3% of patients, respectively. Neither NED extent nor percentage was significantly associated with PD-L1 expression or prognosis. A moderate negative correlation was found between SIS and PD-L1 CPS (rho = -0.48, p\u0026thinsp;=\u0026thinsp;0.051). Strong synaptophysin expression was significantly associated with shorter overall survival (p\u0026thinsp;=\u0026thinsp;0.031).\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003eIn treatment-na\u0026iuml;ve PaNED, higher SIS was correlated with lower PD-L1 CPS values, and strong synaptophysin expression was associated with poorer survival. Assessment of SIS in morphologically suspected neuroendocrine areas may provide additional prognostic information and help predict the PD-L1 response. Larger studies are required to validate these findings.\u003c/p\u003e","manuscriptTitle":"Neuroendocrine differentiation and PD-L1 expression in treatment-naïve prostatic adenocarcinoma: Clinicopathological correlates and prognostic significance","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-12-22 08:48:19","doi":"10.21203/rs.3.rs-8180352/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-12-26T13:20:32+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-12-25T19:16:19+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-12-25T11:10:25+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"148676185650878600216986309093765481148","date":"2025-12-25T09:20:54+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"240245766624671152657291528882230410042","date":"2025-12-13T15:17:01+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-12-11T14:55:45+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-12-11T14:53:02+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-12-09T06:24:15+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-12-08T19:24:07+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Urology","date":"2025-12-08T19:17:36+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-urology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"buro","sideBox":"Learn more about [BMC Urology](http://bmcurol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/buro/default.aspx","title":"BMC Urology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"9b062e68-6da3-48b3-847a-429d38932f06","owner":[],"postedDate":"December 22nd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2026-01-19T17:06:58+00:00","versionOfRecord":{"articleIdentity":"rs-8180352","link":"https://doi.org/10.1186/s12894-026-02053-0","journal":{"identity":"bmc-urology","isVorOnly":false,"title":"BMC Urology"},"publishedOn":"2026-01-17 16:30:23","publishedOnDateReadable":"January 17th, 2026"},"versionCreatedAt":"2025-12-22 08:48:19","video":"","vorDoi":"10.1186/s12894-026-02053-0","vorDoiUrl":"https://doi.org/10.1186/s12894-026-02053-0","workflowStages":[]},"version":"v1","identity":"rs-8180352","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8180352","identity":"rs-8180352","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}