HER2 Evaluation in Uterine Serous Carcinoma: Diagnostic Agreement Between Biopsy and Resection Samples

HER2 Evaluation in Uterine Serous Carcinoma: Diagnostic Agreement Between Biopsy and Resection Samples | 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 HER2 Evaluation in Uterine Serous Carcinoma: Diagnostic Agreement Between Biopsy and Resection Samples Zeynep Bayramoglu, Denizhan Bayramoglu, Safiye Aktas This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7820482/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 26 Dec, 2025 Read the published version in BMC Women's Health → Version 1 posted 17 You are reading this latest preprint version Abstract Background Uterine serous carcinoma (USC) is a very aggressive variant of endometrial cancer, contributing to a disproportionate incidence of recurrences and cancer-related mortality, albeit representing a minority of cases. HER2 overexpression and amplification have become important prognostic and predictive indicators in USC, endorsing the application of HER2-targeted treatments. Nonetheless, obstacles including intratumoral heterogeneity and inconsistencies between biopsy and resection tissues hinder precise HER2 evaluation. Methods This retrospective analysis examined 40 instances of USC diagnosed from 2010 to 2020. Expressions of HER2, ER, PR, and Ki-67 were analyzed via immunohistochemistry (IHC), whereas HER2 gene amplification was determined using chromogenic in situ hybridization (CISH). The concordance between biopsy and resection specimens was evaluated. The statistical associations between HER2 status and clinicopathological factors were analyzed utilizing t-tests and chi-square tests. Results HER2 positive demonstrated a strong link with elevated FIGO stage (p = 0.0060) and an enhanced Ki-67 proliferation index (p = 0.0002), indicating a relationship with more aggressive illness. A strong concordance was established between biopsy and resection HER2 values (PPV = 100%, NPV = 91.4%), however differences were identified in 7 instances. CISH was negative in all IHC 0 patients and positive in 3 of the 2 + cases. HER2 gene amplification was detected in one IHC 1 + instance, underscoring the clinical significance of HER2-low tumors in USC and highlighting the necessity of molecular confirmation in ambiguous cases. Conclusion The precise evaluation of HER2 in USC is essential but hindered by tumor heterogeneity and the type of sample used. Standardized HER2 testing criteria unique to USC, along with the evaluation of HER2-low tumors and retesting procedures in metastatic contexts, are crucial for enhancing therapy outcomes. Uterine serous carcinoma HER2 immunohistochemistry gene amplification CISH tumor heterogeneity biopsy resection targeted therapy Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 INTRODUCTION Uterine tumors have the greatest incidence and the second highest fatality rate among gynecologic malignancies in the United States. Uterine serous carcinomas (USCs) constitute about 3–10% of all endometrial cancer diagnoses, although they account for around 50% of recurrences and over 40% of fatalities associated to endometrial cancer ( 1 – 3 ). Consequently, USCs significantly impact morbidity and mortality rates. Five-year survival rates vary between 18% and 55%, and standard treatment approaches—consisting of thorough surgical staging followed by platinum-based chemotherapy—frequently prove inadequate, especially in cases of severe or recurring cancer. This highlights an important clinical necessity for the creation of innovative and more efficacious therapy strategies ( 5 ). In recent years, human epidermal growth factor receptor 2 (HER2) has become a significant prognostic indicator and therapeutic target, especially in breast, gastric, and colorectal malignancies. HER2 is a transmembrane oncoprotein that is essential for cellular proliferation, survival, and growth signaling pathways. Data from clinical trials reported in 2018 validated the prognostic and predictive importance of HER2 in patients with advanced or recurrent uterine serous carcinoma (USC) ( 6 , 7 ). The use of anti-HER2 targeted therapy with chemotherapy markedly enhanced both progression-free survival and overall survival in this patient population. Consequently, HER2 testing has swiftly evolved into a standard auxiliary test during diagnosis. Approximately 25–35% of urothelial carcinoma cases demonstrate HER2 protein overexpression and/or gene amplification. The extensive implementation of HER2 testing in USC has uncovered considerable diversity in reported HER2 positivity rates, primarily because to discrepancies in testing methodology, interpretation criteria, and scoring systems. HER2 positive has varied from 12.3% according to the 2007 ASCO/CAP breast cancer guidelines, to 16.3% under the 2018 guidelines, and decreased to 10.5% using next-generation sequencing (NGS) techniques ( 8 , 9 ). This diversity underscores the necessity for uniform testing methodologies to enhance patient selection. The evaluation of HER2 in USC poses distinct problems, including as tumor heterogeneity and particular staining patterns. Inconsistencies in HER2 status have been documented among biopsy specimens, hysterectomy samples, and metastatic lesions. Discordance between biopsy and hysterectomy specimens has been often seen. This study aims to examine HER2 status in endometrial biopsy and hysterectomy materials from the same USC patients utilizing immunohistochemistry (IHC) and in situ hybridization (ISH) techniques. Our objective is to address existing testing problems and to facilitate the creation of USC-specific standardized HER2 testing recommendations. MATERIALS AND METHODS This retrospective analysis examined archival data of 40 patients diagnosed with serous-type endometrial cancer at our institution from 2010 to 2020. Immunohistochemical (IHC) tests were done on sections derived from paraffin-embedded blocks of both endometrial biopsy and hysterectomy materials from the selected cases. The indicators evaluated in the IHC analysis comprised HER2, estrogen receptor (ER), progesterone receptor (PR), and Ki-67. HER2 expression was assessed according to the standards set by the American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) ( 9 ). HER2 scoring was classified as 0, 1+, 2+, or 3+. All cases underwent chromogenic in situ hybridization (CISH) investigation to ascertain the HER2/CEP17 ratio. Expression levels of ER and PR were assessed by the H-score method, determined by multiplying staining intensity (+ 1, + 2, +3) by the percentage of positively stained cells. Ki-67 was assessed as the proportion of positively stained nuclei. The occurrence or non-occurrence of lymphovascular invasion (LVI) was documented. Tumor staging was conducted in accordance with the FIGO classification system. Data analysis was performed utilizing Python 3.11 alongside the Pandas, SciPy, and Seaborn modules. Continuous variables were assessed with independent-sample t-tests, while categorical variables were evaluated using the chi-square test. The predictive utility of HER2 positivity in biopsy specimens for corresponding surgical specimens was assessed regarding sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). Data were additionally represented through correlation heatmaps and boxplots. A p-value of less than 0.05 was deemed statistically significant. RESULTS The study comprised 40 cases of serous endometrial cancer. The average age was 72.6 years in the HER2-positive cohort and 69.6 years in the HER2-negative cohort (p = 0.155). In seven cases, HER2 scores varied between biopsy and resection tissues. No statistically significant changes were found in estrogen receptor (ER) expression (22.58 vs. 15.56, p = 0.4920) or progesterone receptor (PR) expression (4.84 vs. 4.44, p = 0.9380) when comparing clinicopathologic characteristics between HER2-positive and HER2-negative groups. Ki-67 expression was markedly reduced in HER2-positive cases relative to HER2-negative instances (67.35 vs. 77.67, p = 0.0002) (Figure-1). The FIGO stage was significantly elevated in the HER2-positive group (mean 3.33) compared to the HER2-negative group (mean 2.26), with p = 0.0060, suggesting a connection between HER2 overexpression and advanced disease stage (Table-1). The heatmap visualization demonstrated relationships between HER2 positive and clinical/pathological factors (ER, PR, Ki-67, age, LVI, FIGO). A robust positive connection was specifically seen between HER2 and both Ki-67 and FIGO stage. Conversely, weak or negative relationships were identified between HER2 and ER/PR expression (Figure-2). Histopathological examination revealed that the tumors were composed of papillary, glandular, or micropapillary architectures showing marked nuclear atypia (Figure-3). The tumor cells demonstrated pleomorphism with prominent nucleoli. IHC analysis showed strong (3+) membranous HER2 overexpression in a subset of cases (Figure-4). Furthermore, chromogenic in situ hybridization (CISH) was performed on these cases to evaluate HER2 gene amplification status (Fig. 5 – 6 ). The positive predictive value (PPV) of biopsy-derived HER2 testing was 100%, but the negative predictive value (NPV) was 91.4%, signifying that HER2 negativity in biopsy samples accurately predicted negativity in the resection material with 91.4% precision. In HER2 testing utilizing resection specimens, the positive predictive value (PPV) was determined to be 98%, whereas the negative predictive value (NPV) was 96%. Concerning HER2 IHC scoring: all instances with a HER2 score of 0 were CISH-negative. Of the instances with a score of 1+, only one had CISH positive. Among individuals with a HER2 score of 2+, three were identified as CISH-positive. DISCUSSION Uterine serous carcinoma (USC) is an aggressive variant of endometrial carcinoma, characterized by a high incidence and the second-highest fatality rate among gynecologic cancers. Although it constitutes about 3–10% of all endometrial cancer cases, it is responsible for over 50% of recurrences and almost 40% of fatalities associated with endometrial cancer ( 11 ). Owing to its resistance to standard therapy and elevated recurrence rates, there is an imperative demand for innovative and more efficacious therapeutic alternatives in advanced or recurring disease. In recent years, HER2 has been established as both a predictive biomarker and a therapeutic target in USC ( 6 , 12 – 15 ). In patients with advanced or recurrent USC, including anti-HER2 targeted therapy into standard chemotherapy has shown substantial enhancements in progression-free survival (PFS) and overall survival (OS). These results prompted the inclusion of trastuzumab in the National Comprehensive Cancer Network (NCCN) guidelines as a recommended adjunct to chemotherapy for HER2-positive recurrent or advanced uterine serous carcinoma (USC) ( 16 ). Consequently, HER2 testing has become a standard supplementary evaluation at the time of diagnosis. Approximately 25–35% of urothelial carcinoma cases have HER2 protein overexpression and/or gene amplification. Reported HER2 positive rates in USC exhibit significant variability, mostly attributable to discrepancies in testing platforms, interpretation criteria, and scoring methods. Due to its predictive and prognostic importance, HER2 evaluation is essential in the management of USC. Our research provides significant insights into HER2 testing by assessing both biopsy and surgical resection specimens from 40 USC cases. We noted a significant correlation between HER2 expression in biopsy specimens and matched resection samples, reinforcing the clinical relevance of biopsy-derived HER2 data in informing therapy options. Prior research has likewise indicated elevated concordance rates ( 12 , 17 ). HER2-positive tumors were substantially correlated with advanced FIGO stage and increased Ki-67 proliferation index. This substantiates the assertion that HER2 positive correlates with more aggressive disease characteristics, advanced stages, and worse prognosis in USC. Ki-67 is a recognized indicator of cellular proliferation, and its correlation with HER2 positive aligns with the aggressive nature of HER2-overexpressing malignancies. The weak or negative connection between HER2 and hormone receptors (ER/PR) indicates that HER2-positive uterine serous carcinomas are likely hormone receptor–negative and exhibit greater biological aggressiveness ( 12 , 18 ). HER2 testing in USC has specific obstacles that differ from those in breast cancer, such as intratumoral heterogeneity (reported in 31–97% of patients) and basal-lateral/lateral membranous staining patterns (seen in about 74% of cases). These characteristics underscore the necessity for USC-specific evaluation standards. Tumor heterogeneity can result in false-negative outcomes in tiny samples, which may not accurately represent the comprehensive HER2 status of the tumor. In our biopsy specimens, the positive predictive value (PPV) for HER2 was 100%, signifying that HER2 positivity in biopsy is an exceptionally reliable result. The negative predictive value (NPV) was 91.4%, indicating a minor false-negative rate of 8.6%. The data indicate that tumor heterogeneity in tiny biopsies may lead to overlooked HER2-positive patients ( 19 ). In resection specimens, the positive predictive value (PPV) was 98%, and the negative predictive value (NPV) was 96%, indicating substantial dependability, despite a little rate of discordance. This underscores the significance of sample type and pre-analytical variables—such as cold ischemia duration in hysterectomy specimens—that may diminish HER2 protein expression and influence test outcomes. Certain investigations have documented instances in which biopsy specimens tested HER2-positive, although the associated resection specimens were negative. All USC cases in our investigation were subjected to HER2 testing utilizing both IHC and CISH methodologies. All cases with an IHC score of 0 exhibited no HER2 gene amplification using CISH, indicating that gene amplification is highly improbable in this cohort and suggesting that further molecular testing may be unnecessary. Notably, a case with an IHC score of 1 + had CISH positivity, indicating that gene amplification may infrequently arise even in tumors with diminished HER2 expression. This discovery corresponds with the observations made by Buza et al., who noted low-level amplification in certain 1 + USC cases (Table-2). Additionally, CISH yielded positive results in three instances with an IHC score of 2+, thereby strengthening the ASCO/CAP guideline statement that molecular confirmation (e.g., CISH or FISH) is crucial for equivocal (2+) patients. Since IHC 2 + values do not unequivocally signify HER2 positive, confirmation testing is essential for precise treatment decision-making. Our results endorse the concurrent application of IHC and CISH, especially in borderline (1 + and 2+) cases, to precisely ascertain HER2 status. The HER2 amplification rate in our investigation aligns with the 17–35% range documented in the literature, and the association between IHC scores and CISH results substantiates the reliability of this dual methodology ( 17 ). The CISH positivity in a single IHC 1 + case is significant and substantiates the presence of infrequent HER2-amplified tumors with diminished IHC expression, enhancing the current discussion on the “HER2-low” classification. Buza et al. and Banet et al. showed HER2 amplification in 13–14% of IHC 1 + USC cases, highlighting the necessity for additional exploration of this subgroup in USC ( 12 , 21 ). The detection of HER2 amplification in 2 + instances further emphasizes the diagnostic significance of reflex CISH testing in this ambiguous category, aligning with prior research that reports amplification rates of 26–31% in IHC 2 + USC cases. This unequivocally illustrates that IHC 2 + alone is inadequate for determining HER2 status, necessitating confirmatory molecular testing for the right selection of patients for targeted therapy. A substantial cohort research by Klc et al., encompassing 2,192 USC tumors, indicated an overall concordance rate of 98.9% between IHC and CISH in accordance with the 2018 ASCO/CAP recommendations ( 6 , 8 , 9 ). Our findings underscore the intricacy of HER2 testing in USC and the imperative for standardized, USC-specific testing methodologies. Due to the variability in HER2 positivity rates produced by different testing platforms (IHC, CISH, NGS) and grading systems (2007 vs. 2018 ASCO/CAP), precise patient selection for targeted HER2 therapy is critically important. CONCLUSION Our findings underscore the vital significance and intrinsic difficulties of precisely evaluating HER2 status in USC. Intratumoral heterogeneity and variations between specimen types (biopsy versus resection) present considerable challenges to accurate HER2 assessment. Conclusive testing protocols must finally be corroborated by therapy responses and clinical results. Future research should concentrate on the standardization of HER2 scoring standards pertinent to USC, exploring the clinical and biological significance of "HER2-low" cancers, and assessing the prognostic and predictive consequences of tumor heterogeneity. Moreover, recent evidence indicates the necessity to reevaluate HER2 status in specific clinical scenarios, such as metastatic disease, necessitating additional exploration of the ideal timing and methods for HER2 re-testing. Abbreviations Uterine serous carcinoma (USC); immunohistochemistry (IHC); chromogenic in situ hybridization (CISH); human epidermal growth factor receptor 2 (HER2); positive predictive value (PPV); negative predictive value (NPV); progression-free survival (PFS); overall survival (OS). Declarations Ethics approval and consent to participate The study was approved by the Hamidiye Scientific Research Ethics Committee of the Faculty of Medicine, University of Health Sciences (Approval No: 21/213). The requirement for informed consent was waived by the same committee because the study used anonymized patient data. The study was conducted in accordance with the principles of the Declaration of Helsinki. Consent for publication Not applicable. Competing interests The authors declare that they have no competing interests. Funding This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors. Author Contribution ZB DB SA conceived and designed the study. ZB DB collected and analyzed the data. ZB SA drafted the manuscript. All authors read and approved the final version of the manuscript. Acknowledgements None. Data Availability The datasets generated and/or analyzed during the current study are available from the corresponding author on reasonable request. References Surveillance, Epidemiology and End Results Program. Cancer stat facts: uterine cancer. National Cancer Institute. Accessed January 28, 2023. https://seer.cancer.gov/statfacts/html/corp.html Matthews RP, Hutchinson-Colas J, Maiman M, et al. Papillary serous and clear cell type lead to poor prognosis of endometrial carcinoma in black women. Gynecol Oncol. 1997;65(2):206–12. https://doi.org/10.1006/gyno.1997.4617 . Hamilton CA, Cheung MK, Osann K, et al. Uterine papillary serous and clear cell carcinomas predict for poorer survival compared to grade 3 endometrioid corpus cancers. Br J Cancer. 2006;94(5):642–6. https://doi.org/10.1038/sj.bjc.6603012 . Talia KL, Banet N, Buza N. The role of HER2 as a therapeutic biomarker in gynaecological malignancy: potential for use beyond uterine serous carcinoma. Pathology. 2023;55(1):8–18. Buza N. HER2 testing in endometrial serous carcinoma: time for standardized pathology practice to meet the clinical demand. Arch Pathol Lab Med. 2021;145(6):687–91. Klc TR, Wu S, Wilhite AM, Jones NL, Powell MA, Olawaiye A, Erickson BK. HER2 in Uterine Serous Carcinoma: Testing platforms and implications for targeted therapy. Gynecol Oncol. 2022;167(2):289–94. Connell CM, Doherty GJ. (2017). Activating HER2 mutations as emerging targets in multiple solid cancers. ESMO open, 2(5), e000279.). ,Wolff AC, Hammond ME, Schwartz JN, et al. American Society of Clinical Oncology/College of American Pathologists guideline recommendations for human epidermal growth factor receptor 2 testing in breast cancer. Arch Pathol Lab Med. 2007;131(1):18–43. ,Wolff AC, Hammond MEH, Allison KH, et al. Human Epidermal Growth Factor Receptor 2 testing in breast cancer: American Society of Clinical Oncology/College of American Pathologists clinical practice guideline focused update. Arch Pathol Lab Med. 2018;142(11):1364–82. Buza, Natalia MD. January. HER2 Testing and Reporting in Endometrial Serous Carcinoma: Practical Recommendations for HER2 Immunohistochemistry and Fluorescent In Situ Hybridization: Proceedings of the ISGyP Companion Society Session at the 2020 USCAP Annual Meeting. International Journal of Gynecological Pathology 40(1):p 17–23, 2021. | 10.1097/PGP.0000000000000711 McGunigal M, Liu J, Kalir T, Chadha M, Gupta V. Survival differences among uterine papillary serous, clear cell and grade 3 endometrioid adenocarcinoma endometrial cancers: a National Cancer Database Analysis. Int J Gynecol Cancer. 2017;27(1):85–92. https://doi.org/10.1097/IGC.0000000000000844 . Buza N, English DP, Santin AD, Hui P. Toward standard HER2 testing of endometrial serous carcinoma: 4-year experience at a large academic center and recommendations for clinical practice. Mod Pathol. 2013;26(12):1605–12. https://doi.org/10.1038/modpathol.2013.113 . Erickson BK, Najjar O, Damast S, et al. Human epidermal growth factor 2 (HER2) in early stage uterine serous carcinoma: a multi-institutional cohort study. Gynecol Oncol. 2020;159(1):17–22. https://doi.org/10.1016/j.ygyno.2020.07.016 . Santin AD, Bellone S, Siegel ER, et al. Racial differences in the overexpression of epidermal growth factor type II receptor (HER2/ neu): a major prognostic indicator in uterine serous papillary cancer. Am J Obstet Gynecol. 2005;192(3):813–8. https://doi.org/10.1016/j. ajog.2004.10.605. Fader AN, Roque DM, Siegel E, et al. Randomized phase II trial of carboplatin-paclitaxel versus carboplatin-paclitaxel-trastuzumab in uterine serous carcinomas that overexpress human epidermal growth factor receptor 2/neu. J Clin Oncol. 2018;36(20):2044–51. https://doi.org/10.1200/JCO.2017.76.5966 . National Comprehensive Cancer Network. Uterine Neoplasms. Version 4. 2019. https://www.nccn.org/professionals/physician_gls/#site . Accessed October 6, 2019. Slomovitz BM, Broaddus R, Burke TW et al. HER2/neu overexpression and amplification in uterine serous carcinoma. Gynecol Oncol. 2020. Köbel M, Rahimi K, Rambau PF et al. An Immunohistochemical Algorithm for Molecular Classification of Endometrial Carcinoma: A Provisional Strategy. Mod Pathol. 2018. Buza N, Hui P. Marked heterogeneity of HER2/NEU gene amplification in endometrial serous carcinoma. Genes Chromosomes Cancer. 2013;52(12):1178–86. Halle MK, Tangen IL, Berg HF, et al. HER2 expression patterns in paired primary and metastatic endometrial cancer lesions. Br J Cancer. 2018;118:378–87. Banet N, Shahi M, Batista D, Yonescu R, Tanner EJ, Fader AN, Cimino-Mathews A. HER-2 amplification in uterine serous carcinoma and serous endometrial intraepithelial carcinoma. Am J Surg Pathol. 2021;45(5):708–15. Tables Table-1: Comparison of Clinicopathologic Variables According to HER2 Status (Note: Bold values indicate statistically significant differences ( p < 0.05). Variable HER2 Positive (Mean) HER2 Negative (Mean) p -value ER 22.58 15.56 0.4920 PR 4.84 4.44 0.9380 Ki-67 (%) 67.35 77.67 0.0002 FIGO Stage 3.33 2.26 0.0060 Table-2: HER2 Positivity Rates in Serous Endometrial Carcinoma – Comparison of Current Study with Literature Study Year N (Cases) HER2 Positive (%) IHC 3+ IHC 2+ IHC 1+ (CISH+) Buza et al. 2013 51 32% 13 12 2 Slomovitz et al. 2020 122 35% — — — Banet et al. 2021 83 28% 16 8 1 Current Study (Yours) 2025 40 22.5% 5 3 1 Additional Declarations No competing interests reported. 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14:49:44","extension":"html","order_by":16,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":71828,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7820482/v1/9998048e9f4a57f2b37e0cb9.html"},{"id":95845489,"identity":"e8a18990-53d7-478f-af0d-27e9fafed5cc","added_by":"auto","created_at":"2025-11-13 14:49:44","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":47891,"visible":true,"origin":"","legend":"\u003cp\u003eDistribution of KI67 by CERBB2 Status.\u003c/p\u003e","description":"","filename":"image1.png","url":"https://assets-eu.researchsquare.com/files/rs-7820482/v1/c23969e47815be10ce10c1ef.png"},{"id":96240953,"identity":"91b4d7e6-09ba-4800-81fd-7ac0cda6c49d","added_by":"auto","created_at":"2025-11-19 07:09:46","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":143949,"visible":true,"origin":"","legend":"\u003cp\u003eCorrelation heatmap.\u003c/p\u003e","description":"","filename":"image2.png","url":"https://assets-eu.researchsquare.com/files/rs-7820482/v1/0c9376ba197040d971aee3d5.png"},{"id":96240964,"identity":"71e1fb5b-0957-45c1-984a-c186d1bfdcc8","added_by":"auto","created_at":"2025-11-19 07:09:47","extension":"jpeg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":100035,"visible":true,"origin":"","legend":"\u003cp\u003eHistopathological examination at high magnification showing serous endometrial carcinoma with papillary architecture and marked nuclear atypia (H\u0026amp;E stain)\u003c/p\u003e","description":"","filename":"image3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7820482/v1/da5e02be2ce0927ec967a334.jpeg"},{"id":95845490,"identity":"c3dc6293-8239-4897-82c9-8557c66b2bc6","added_by":"auto","created_at":"2025-11-13 14:49:44","extension":"jpeg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":95106,"visible":true,"origin":"","legend":"\u003cp\u003eImmunohistochemical staining showing HER2 overexpression with a characteristic U-shaped membranous pattern in serous endometrial carcinoma.”\u003c/p\u003e","description":"","filename":"image4.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7820482/v1/06b5ce8bbb51f484a8f88d51.jpeg"},{"id":96240606,"identity":"fe21ce36-80c2-4c0a-8785-38698efac48f","added_by":"auto","created_at":"2025-11-19 07:09:10","extension":"jpeg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":68264,"visible":true,"origin":"","legend":"\u003cp\u003eIn situ hybridization (ISH) analysis showing no evidence of HER2 gene amplification in serous endometrial carcinoma.\u003c/p\u003e","description":"","filename":"image5.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7820482/v1/886e990e6eda9f15973ef3d6.jpeg"},{"id":95845497,"identity":"c0093efb-0cec-4edb-8318-000362c90d53","added_by":"auto","created_at":"2025-11-13 14:49:44","extension":"jpeg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":49552,"visible":true,"origin":"","legend":"\u003cp\u003eIn situ hybridization (ISH) analysis demonstrating HER2 gene amplification in serous endometrial carcinoma\u003c/p\u003e","description":"","filename":"image6.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7820482/v1/6f77f5ccb8597c796e58a605.jpeg"},{"id":99172395,"identity":"6451a650-1056-4199-9e85-57319df74a2f","added_by":"auto","created_at":"2025-12-29 16:08:48","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":990348,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7820482/v1/36090de9-7a10-44ca-b5fd-2d9ea5b1dc70.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"HER2 Evaluation in Uterine Serous Carcinoma: Diagnostic Agreement Between Biopsy and Resection Samples","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eUterine tumors have the greatest incidence and the second highest fatality rate among gynecologic malignancies in the United States. Uterine serous carcinomas (USCs) constitute about 3\u0026ndash;10% of all endometrial cancer diagnoses, although they account for around 50% of recurrences and over 40% of fatalities associated to endometrial cancer (\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e). Consequently, USCs significantly impact morbidity and mortality rates. Five-year survival rates vary between 18% and 55%, and standard treatment approaches\u0026mdash;consisting of thorough surgical staging followed by platinum-based chemotherapy\u0026mdash;frequently prove inadequate, especially in cases of severe or recurring cancer. This highlights an important clinical necessity for the creation of innovative and more efficacious therapy strategies (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eIn recent years, human epidermal growth factor receptor 2 (HER2) has become a significant prognostic indicator and therapeutic target, especially in breast, gastric, and colorectal malignancies. HER2 is a transmembrane oncoprotein that is essential for cellular proliferation, survival, and growth signaling pathways. Data from clinical trials reported in 2018 validated the prognostic and predictive importance of HER2 in patients with advanced or recurrent uterine serous carcinoma (USC) (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e). The use of anti-HER2 targeted therapy with chemotherapy markedly enhanced both progression-free survival and overall survival in this patient population. Consequently, HER2 testing has swiftly evolved into a standard auxiliary test during diagnosis. Approximately 25\u0026ndash;35% of urothelial carcinoma cases demonstrate HER2 protein overexpression and/or gene amplification.\u003c/p\u003e\u003cp\u003eThe extensive implementation of HER2 testing in USC has uncovered considerable diversity in reported HER2 positivity rates, primarily because to discrepancies in testing methodology, interpretation criteria, and scoring systems. HER2 positive has varied from 12.3% according to the 2007 ASCO/CAP breast cancer guidelines, to 16.3% under the 2018 guidelines, and decreased to 10.5% using next-generation sequencing (NGS) techniques (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e). This diversity underscores the necessity for uniform testing methodologies to enhance patient selection. The evaluation of HER2 in USC poses distinct problems, including as tumor heterogeneity and particular staining patterns. Inconsistencies in HER2 status have been documented among biopsy specimens, hysterectomy samples, and metastatic lesions. Discordance between biopsy and hysterectomy specimens has been often seen.\u003c/p\u003e\u003cp\u003eThis study aims to examine HER2 status in endometrial biopsy and hysterectomy materials from the same USC patients utilizing immunohistochemistry (IHC) and in situ hybridization (ISH) techniques. Our objective is to address existing testing problems and to facilitate the creation of USC-specific standardized HER2 testing recommendations.\u003c/p\u003e"},{"header":"MATERIALS AND METHODS","content":"\u003cp\u003eThis retrospective analysis examined archival data of 40 patients diagnosed with serous-type endometrial cancer at our institution from 2010 to 2020. Immunohistochemical (IHC) tests were done on sections derived from paraffin-embedded blocks of both endometrial biopsy and hysterectomy materials from the selected cases. The indicators evaluated in the IHC analysis comprised HER2, estrogen receptor (ER), progesterone receptor (PR), and Ki-67. HER2 expression was assessed according to the standards set by the American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e). HER2 scoring was classified as 0, 1+, 2+, or 3+. All cases underwent chromogenic in situ hybridization (CISH) investigation to ascertain the HER2/CEP17 ratio.\u003c/p\u003e\u003cp\u003eExpression levels of ER and PR were assessed by the H-score method, determined by multiplying staining intensity (+\u0026thinsp;1, +\u0026thinsp;2, +3) by the percentage of positively stained cells. Ki-67 was assessed as the proportion of positively stained nuclei. The occurrence or non-occurrence of lymphovascular invasion (LVI) was documented. Tumor staging was conducted in accordance with the FIGO classification system.\u003c/p\u003e\u003cp\u003eData analysis was performed utilizing Python 3.11 alongside the Pandas, SciPy, and Seaborn modules. Continuous variables were assessed with independent-sample t-tests, while categorical variables were evaluated using the chi-square test. The predictive utility of HER2 positivity in biopsy specimens for corresponding surgical specimens was assessed regarding sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). Data were additionally represented through correlation heatmaps and boxplots. A p-value of less than 0.05 was deemed statistically significant.\u003c/p\u003e"},{"header":"RESULTS","content":"\u003cp\u003eThe study comprised 40 cases of serous endometrial cancer. The average age was 72.6 years in the HER2-positive cohort and 69.6 years in the HER2-negative cohort (p\u0026thinsp;=\u0026thinsp;0.155). In seven cases, HER2 scores varied between biopsy and resection tissues. No statistically significant changes were found in estrogen receptor (ER) expression (22.58 vs. 15.56, p\u0026thinsp;=\u0026thinsp;0.4920) or progesterone receptor (PR) expression (4.84 vs. 4.44, p\u0026thinsp;=\u0026thinsp;0.9380) when comparing clinicopathologic characteristics between HER2-positive and HER2-negative groups. Ki-67 expression was markedly reduced in HER2-positive cases relative to HER2-negative instances (67.35 vs. 77.67, p\u0026thinsp;=\u0026thinsp;0.0002) (Figure-1). The FIGO stage was significantly elevated in the HER2-positive group (mean 3.33) compared to the HER2-negative group (mean 2.26), with p\u0026thinsp;=\u0026thinsp;0.0060, suggesting a connection between HER2 overexpression and advanced disease stage (Table-1). The heatmap visualization demonstrated relationships between HER2 positive and clinical/pathological factors (ER, PR, Ki-67, age, LVI, FIGO). A robust positive connection was specifically seen between HER2 and both Ki-67 and FIGO stage. Conversely, weak or negative relationships were identified between HER2 and ER/PR expression (Figure-2).\u003c/p\u003e\u003cp\u003eHistopathological examination revealed that the tumors were composed of papillary, glandular, or micropapillary architectures showing marked nuclear atypia (Figure-3). The tumor cells demonstrated pleomorphism with prominent nucleoli. IHC analysis showed strong (3+) membranous HER2 overexpression in a subset of cases (Figure-4). Furthermore, chromogenic in situ hybridization (CISH) was performed on these cases to evaluate HER2 gene amplification status (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e\u0026ndash;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eThe positive predictive value (PPV) of biopsy-derived HER2 testing was 100%, but the negative predictive value (NPV) was 91.4%, signifying that HER2 negativity in biopsy samples accurately predicted negativity in the resection material with 91.4% precision. In HER2 testing utilizing resection specimens, the positive predictive value (PPV) was determined to be 98%, whereas the negative predictive value (NPV) was 96%. Concerning HER2 IHC scoring: all instances with a HER2 score of 0 were CISH-negative. Of the instances with a score of 1+, only one had CISH positive. Among individuals with a HER2 score of 2+, three were identified as CISH-positive.\u003c/p\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eUterine serous carcinoma (USC) is an aggressive variant of endometrial carcinoma, characterized by a high incidence and the second-highest fatality rate among gynecologic cancers. Although it constitutes about 3\u0026ndash;10% of all endometrial cancer cases, it is responsible for over 50% of recurrences and almost 40% of fatalities associated with endometrial cancer (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e). Owing to its resistance to standard therapy and elevated recurrence rates, there is an imperative demand for innovative and more efficacious therapeutic alternatives in advanced or recurring disease. In recent years, HER2 has been established as both a predictive biomarker and a therapeutic target in USC (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan additionalcitationids=\"CR13 CR14\" citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e). In patients with advanced or recurrent USC, including anti-HER2 targeted therapy into standard chemotherapy has shown substantial enhancements in progression-free survival (PFS) and overall survival (OS). These results prompted the inclusion of trastuzumab in the National Comprehensive Cancer Network (NCCN) guidelines as a recommended adjunct to chemotherapy for HER2-positive recurrent or advanced uterine serous carcinoma (USC) (\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e). Consequently, HER2 testing has become a standard supplementary evaluation at the time of diagnosis. Approximately 25\u0026ndash;35% of urothelial carcinoma cases have HER2 protein overexpression and/or gene amplification. Reported HER2 positive rates in USC exhibit significant variability, mostly attributable to discrepancies in testing platforms, interpretation criteria, and scoring methods. Due to its predictive and prognostic importance, HER2 evaluation is essential in the management of USC.\u003c/p\u003e\u003cp\u003eOur research provides significant insights into HER2 testing by assessing both biopsy and surgical resection specimens from 40 USC cases. We noted a significant correlation between HER2 expression in biopsy specimens and matched resection samples, reinforcing the clinical relevance of biopsy-derived HER2 data in informing therapy options. Prior research has likewise indicated elevated concordance rates (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e). HER2-positive tumors were substantially correlated with advanced FIGO stage and increased Ki-67 proliferation index. This substantiates the assertion that HER2 positive correlates with more aggressive disease characteristics, advanced stages, and worse prognosis in USC. Ki-67 is a recognized indicator of cellular proliferation, and its correlation with HER2 positive aligns with the aggressive nature of HER2-overexpressing malignancies. The weak or negative connection between HER2 and hormone receptors (ER/PR) indicates that HER2-positive uterine serous carcinomas are likely hormone receptor\u0026ndash;negative and exhibit greater biological aggressiveness (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eHER2 testing in USC has specific obstacles that differ from those in breast cancer, such as intratumoral heterogeneity (reported in 31\u0026ndash;97% of patients) and basal-lateral/lateral membranous staining patterns (seen in about 74% of cases). These characteristics underscore the necessity for USC-specific evaluation standards. Tumor heterogeneity can result in false-negative outcomes in tiny samples, which may not accurately represent the comprehensive HER2 status of the tumor.\u003c/p\u003e\u003cp\u003eIn our biopsy specimens, the positive predictive value (PPV) for HER2 was 100%, signifying that HER2 positivity in biopsy is an exceptionally reliable result. The negative predictive value (NPV) was 91.4%, indicating a minor false-negative rate of 8.6%. The data indicate that tumor heterogeneity in tiny biopsies may lead to overlooked HER2-positive patients (\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e). In resection specimens, the positive predictive value (PPV) was 98%, and the negative predictive value (NPV) was 96%, indicating substantial dependability, despite a little rate of discordance. This underscores the significance of sample type and pre-analytical variables\u0026mdash;such as cold ischemia duration in hysterectomy specimens\u0026mdash;that may diminish HER2 protein expression and influence test outcomes. Certain investigations have documented instances in which biopsy specimens tested HER2-positive, although the associated resection specimens were negative.\u003c/p\u003e\u003cp\u003eAll USC cases in our investigation were subjected to HER2 testing utilizing both IHC and CISH methodologies. All cases with an IHC score of 0 exhibited no HER2 gene amplification using CISH, indicating that gene amplification is highly improbable in this cohort and suggesting that further molecular testing may be unnecessary. Notably, a case with an IHC score of 1\u0026thinsp;+\u0026thinsp;had CISH positivity, indicating that gene amplification may infrequently arise even in tumors with diminished HER2 expression. This discovery corresponds with the observations made by Buza et al., who noted low-level amplification in certain 1\u0026thinsp;+\u0026thinsp;USC cases (Table-2). Additionally, CISH yielded positive results in three instances with an IHC score of 2+, thereby strengthening the ASCO/CAP guideline statement that molecular confirmation (e.g., CISH or FISH) is crucial for equivocal (2+) patients. Since IHC 2\u0026thinsp;+\u0026thinsp;values do not unequivocally signify HER2 positive, confirmation testing is essential for precise treatment decision-making.\u003c/p\u003e\u003cp\u003eOur results endorse the concurrent application of IHC and CISH, especially in borderline (1\u0026thinsp;+\u0026thinsp;and 2+) cases, to precisely ascertain HER2 status. The HER2 amplification rate in our investigation aligns with the 17\u0026ndash;35% range documented in the literature, and the association between IHC scores and CISH results substantiates the reliability of this dual methodology (\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e). The CISH positivity in a single IHC 1\u0026thinsp;+\u0026thinsp;case is significant and substantiates the presence of infrequent HER2-amplified tumors with diminished IHC expression, enhancing the current discussion on the \u0026ldquo;HER2-low\u0026rdquo; classification. Buza et al. and Banet et al. showed HER2 amplification in 13\u0026ndash;14% of IHC 1\u0026thinsp;+\u0026thinsp;USC cases, highlighting the necessity for additional exploration of this subgroup in USC (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e). The detection of HER2 amplification in 2\u0026thinsp;+\u0026thinsp;instances further emphasizes the diagnostic significance of reflex CISH testing in this ambiguous category, aligning with prior research that reports amplification rates of 26\u0026ndash;31% in IHC 2\u0026thinsp;+\u0026thinsp;USC cases. This unequivocally illustrates that IHC 2\u0026thinsp;+\u0026thinsp;alone is inadequate for determining HER2 status, necessitating confirmatory molecular testing for the right selection of patients for targeted therapy.\u003c/p\u003e\u003cp\u003eA substantial cohort research by Klc et al., encompassing 2,192 USC tumors, indicated an overall concordance rate of 98.9% between IHC and CISH in accordance with the 2018 ASCO/CAP recommendations (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e). Our findings underscore the intricacy of HER2 testing in USC and the imperative for standardized, USC-specific testing methodologies. Due to the variability in HER2 positivity rates produced by different testing platforms (IHC, CISH, NGS) and grading systems (2007 vs. 2018 ASCO/CAP), precise patient selection for targeted HER2 therapy is critically important.\u003c/p\u003e"},{"header":"CONCLUSION","content":"\u003cp\u003eOur findings underscore the vital significance and intrinsic difficulties of precisely evaluating HER2 status in USC. Intratumoral heterogeneity and variations between specimen types (biopsy versus resection) present considerable challenges to accurate HER2 assessment. Conclusive testing protocols must finally be corroborated by therapy responses and clinical results. Future research should concentrate on the standardization of HER2 scoring standards pertinent to USC, exploring the clinical and biological significance of \"HER2-low\" cancers, and assessing the prognostic and predictive consequences of tumor heterogeneity. Moreover, recent evidence indicates the necessity to reevaluate HER2 status in specific clinical scenarios, such as metastatic disease, necessitating additional exploration of the ideal timing and methods for HER2 re-testing.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eUterine serous carcinoma (USC); immunohistochemistry (IHC); chromogenic in situ hybridization (CISH); human epidermal growth factor receptor 2 (HER2); positive predictive value (PPV); negative predictive value (NPV); progression-free survival (PFS); overall survival (OS).\u003c/p\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003ch2\u003eEthics approval and consent to participate\u003c/h2\u003e\u003cp\u003eThe study was approved by the Hamidiye Scientific Research Ethics Committee of the Faculty of Medicine, University of Health Sciences (Approval No: 21/213). The requirement for informed consent was waived by the same committee because the study used anonymized patient data. The study was conducted in accordance with the principles of the Declaration of Helsinki.\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 received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eZB DB SA conceived and designed the study. ZB DB collected and analyzed the data. ZB SA drafted the manuscript. All authors read 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 analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eSurveillance, Epidemiology and End Results Program. Cancer stat facts: uterine cancer. National Cancer Institute. Accessed January 28, 2023. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://seer.cancer.gov/statfacts/html/corp.html\u003c/span\u003e\u003cspan address=\"https://seer.cancer.gov/statfacts/html/corp.html\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMatthews RP, Hutchinson-Colas J, Maiman M, et al. 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HER2 in Uterine Serous Carcinoma: Testing platforms and implications for targeted therapy. Gynecol Oncol. 2022;167(2):289\u0026ndash;94.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eConnell CM, Doherty GJ. (2017). Activating HER2 mutations as emerging targets in multiple solid cancers. ESMO open, 2(5), e000279.).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003e,Wolff AC, Hammond ME, Schwartz JN, et al. American Society of Clinical Oncology/College of American Pathologists guideline recommendations for human epidermal growth factor receptor 2 testing in breast cancer. Arch Pathol Lab Med. 2007;131(1):18\u0026ndash;43.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003e,Wolff AC, Hammond MEH, Allison KH, et al. Human Epidermal Growth Factor Receptor 2 testing in breast cancer: American Society of Clinical Oncology/College of American Pathologists clinical practice guideline focused update. Arch Pathol Lab Med. 2018;142(11):1364\u0026ndash;82.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBuza, Natalia MD. January. HER2 Testing and Reporting in Endometrial Serous Carcinoma: Practical Recommendations for HER2 Immunohistochemistry and Fluorescent In Situ Hybridization: Proceedings of the ISGyP Companion Society Session at the 2020 USCAP Annual Meeting. International Journal of Gynecological Pathology 40(1):p 17\u0026ndash;23, 2021. | \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1097/PGP.0000000000000711\u003c/span\u003e\u003cspan address=\"10.1097/PGP.0000000000000711\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMcGunigal M, Liu J, Kalir T, Chadha M, Gupta V. Survival differences among uterine papillary serous, clear cell and grade 3 endometrioid adenocarcinoma endometrial cancers: a National Cancer Database Analysis. Int J Gynecol Cancer. 2017;27(1):85\u0026ndash;92. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1097/IGC.0000000000000844\u003c/span\u003e\u003cspan address=\"10.1097/IGC.0000000000000844\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBuza N, English DP, Santin AD, Hui P. Toward standard HER2 testing of endometrial serous carcinoma: 4-year experience at a large academic center and recommendations for clinical practice. Mod Pathol. 2013;26(12):1605\u0026ndash;12. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1038/modpathol.2013.113\u003c/span\u003e\u003cspan address=\"10.1038/modpathol.2013.113\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eErickson BK, Najjar O, Damast S, et al. Human epidermal growth factor 2 (HER2) in early stage uterine serous carcinoma: a multi-institutional cohort study. Gynecol Oncol. 2020;159(1):17\u0026ndash;22. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.ygyno.2020.07.016\u003c/span\u003e\u003cspan address=\"10.1016/j.ygyno.2020.07.016\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSantin AD, Bellone S, Siegel ER, et al. Racial differences in the overexpression of epidermal growth factor type II receptor (HER2/ neu): a major prognostic indicator in uterine serous papillary cancer. Am J Obstet Gynecol. 2005;192(3):813\u0026ndash;8. https://doi.org/10.1016/j. ajog.2004.10.605.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFader AN, Roque DM, Siegel E, et al. Randomized phase II trial of carboplatin-paclitaxel versus carboplatin-paclitaxel-trastuzumab in uterine serous carcinomas that overexpress human epidermal growth factor receptor 2/neu. J Clin Oncol. 2018;36(20):2044\u0026ndash;51. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1200/JCO.2017.76.5966\u003c/span\u003e\u003cspan address=\"10.1200/JCO.2017.76.5966\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eNational Comprehensive Cancer Network. Uterine Neoplasms. Version 4. 2019. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.nccn.org/professionals/physician_gls/#site\u003c/span\u003e\u003cspan address=\"https://www.nccn.org/professionals/physician_gls/#site\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. Accessed October 6, 2019.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSlomovitz BM, Broaddus R, Burke TW et al. HER2/neu overexpression and amplification in uterine serous carcinoma. Gynecol Oncol. 2020.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eK\u0026ouml;bel M, Rahimi K, Rambau PF et al. An Immunohistochemical Algorithm for Molecular Classification of Endometrial Carcinoma: A Provisional Strategy. Mod Pathol. 2018.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBuza N, Hui P. Marked heterogeneity of HER2/NEU gene amplification in endometrial serous carcinoma. Genes Chromosomes Cancer. 2013;52(12):1178\u0026ndash;86.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHalle MK, Tangen IL, Berg HF, et al. HER2 expression patterns in paired primary and metastatic endometrial cancer lesions. Br J Cancer. 2018;118:378\u0026ndash;87.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBanet N, Shahi M, Batista D, Yonescu R, Tanner EJ, Fader AN, Cimino-Mathews A. HER-2 amplification in uterine serous carcinoma and serous endometrial intraepithelial carcinoma. Am J Surg Pathol. 2021;45(5):708\u0026ndash;15.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Tables","content":"\u003cdiv class=\"gridtable\"\u003e\n \u003cdiv class=\"colspec\" align=\"left\"\u003eTable-1: Comparison of Clinicopathologic Variables According to HER2 Status (Note: Bold values indicate statistically significant differences (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/div\u003e\n \u003cdiv class=\"colspec\" align=\"char\"\u003e\u003cbr\u003e\u003c/div\u003e\n \u003ctable id=\"Taba\" border=\"1\"\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eVariable\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eHER2 Positive (Mean)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eHER2 Negative (Mean)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ep\u003c/em\u003e-value\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eER\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e22.58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e15.56\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.4920\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePR\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4.84\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4.44\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.9380\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eKi-67 (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e67.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e77.67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.0002\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFIGO Stage\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.0060\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n \u003cdiv class=\"colspec\" align=\"char\"\u003eTable-2: HER2 Positivity Rates in Serous Endometrial Carcinoma \u0026ndash; Comparison of Current Study with Literature\u0026nbsp;\u003c/div\u003e\n \u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n \u003ctable id=\"Tabb\" border=\"1\"\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eStudy\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eYear\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eN (Cases)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eHER2 Positive (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eIHC 3+\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eIHC 2+\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eIHC 1+ (CISH+)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBuza et al.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2013\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e51\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e32%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSlomovitz et al.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2020\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e122\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e35%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026mdash;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026mdash;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026mdash;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBanet et al.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2021\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e83\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e28%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCurrent Study (Yours)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2025\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e22.5%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\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-womens-health","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bmwh","sideBox":"Learn more about [BMC Women's Health](http://bmcwomenshealth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bmwh/default.aspx","title":"BMC Women's Health","twitterHandle":"","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Uterine serous carcinoma, HER2, immunohistochemistry, gene amplification, CISH, tumor heterogeneity, biopsy, resection, targeted therapy","lastPublishedDoi":"10.21203/rs.3.rs-7820482/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7820482/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\u003cp\u003eUterine serous carcinoma (USC) is a very aggressive variant of endometrial cancer, contributing to a disproportionate incidence of recurrences and cancer-related mortality, albeit representing a minority of cases. HER2 overexpression and amplification have become important prognostic and predictive indicators in USC, endorsing the application of HER2-targeted treatments. Nonetheless, obstacles including intratumoral heterogeneity and inconsistencies between biopsy and resection tissues hinder precise HER2 evaluation.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003eThis retrospective analysis examined 40 instances of USC diagnosed from 2010 to 2020. Expressions of HER2, ER, PR, and Ki-67 were analyzed via immunohistochemistry (IHC), whereas HER2 gene amplification was determined using chromogenic in situ hybridization (CISH). The concordance between biopsy and resection specimens was evaluated. The statistical associations between HER2 status and clinicopathological factors were analyzed utilizing t-tests and chi-square tests.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eHER2 positive demonstrated a strong link with elevated FIGO stage (p\u0026thinsp;=\u0026thinsp;0.0060) and an enhanced Ki-67 proliferation index (p\u0026thinsp;=\u0026thinsp;0.0002), indicating a relationship with more aggressive illness. A strong concordance was established between biopsy and resection HER2 values (PPV\u0026thinsp;=\u0026thinsp;100%, NPV\u0026thinsp;=\u0026thinsp;91.4%), however differences were identified in 7 instances. CISH was negative in all IHC 0 patients and positive in 3 of the 2\u0026thinsp;+\u0026thinsp;cases. HER2 gene amplification was detected in one IHC 1\u0026thinsp;+\u0026thinsp;instance, underscoring the clinical significance of HER2-low tumors in USC and highlighting the necessity of molecular confirmation in ambiguous cases.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e\u003cp\u003eThe precise evaluation of HER2 in USC is essential but hindered by tumor heterogeneity and the type of sample used. Standardized HER2 testing criteria unique to USC, along with the evaluation of HER2-low tumors and retesting procedures in metastatic contexts, are crucial for enhancing therapy outcomes.\u003c/p\u003e","manuscriptTitle":"HER2 Evaluation in Uterine Serous Carcinoma: Diagnostic Agreement Between Biopsy and Resection Samples","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-11-13 14:49:39","doi":"10.21203/rs.3.rs-7820482/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-11-12T19:14:57+00:00","index":"","fulltext":""},{"type":"reviewerAgreed","content":"267268536660588357387655172879887851044","date":"2025-11-07T06:07:08+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-11-06T16:07:57+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"206807399159677112420867598753324181134","date":"2025-11-06T14:52:56+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-11-06T12:01:38+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"46098990800206495951176764926407634378","date":"2025-11-05T17:16:41+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-11-04T13:43:36+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"161122417427423181564728091429968430611","date":"2025-11-04T11:07:02+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"335561312730084878753638948120485533940","date":"2025-11-04T08:21:36+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"186456212366959608858265524426630284040","date":"2025-11-04T06:50:29+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"37752683908519330026293638506419080261","date":"2025-11-03T21:44:43+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"89599786204016352663515010042859281312","date":"2025-11-03T20:57:06+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-11-03T20:52:24+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-11-03T07:18:36+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-10-17T18:36:24+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-10-17T18:05:12+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Women's Health","date":"2025-10-17T18:02:42+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-womens-health","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bmwh","sideBox":"Learn more about [BMC Women's Health](http://bmcwomenshealth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bmwh/default.aspx","title":"BMC Women's Health","twitterHandle":"","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"d1bff805-5808-4d00-a9d8-6c69da1646e0","owner":[],"postedDate":"November 13th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-12-29T16:03:20+00:00","versionOfRecord":{"articleIdentity":"rs-7820482","link":"https://doi.org/10.1186/s12905-025-04235-8","journal":{"identity":"bmc-womens-health","isVorOnly":false,"title":"BMC Women's Health"},"publishedOn":"2025-12-26 15:58:26","publishedOnDateReadable":"December 26th, 2025"},"versionCreatedAt":"2025-11-13 14:49:39","video":"","vorDoi":"10.1186/s12905-025-04235-8","vorDoiUrl":"https://doi.org/10.1186/s12905-025-04235-8","workflowStages":[]},"version":"v1","identity":"rs-7820482","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7820482","identity":"rs-7820482","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}