Validation and Assessment of HER2 FISH Probe for Endometrial Serous Carcinoma

Introduction: Primary endometrial serous carcinoma accounts for less than 10% of endometrial carcinomas but is responsible for 40–80% of deaths.1 HER2 has been shown to be an effective therapeutic target in endometrial serous carcinoma.2,3 Buza et al has estimated that there is HER2 overexpression in 25–30% endometrial high grade serous caricnomas, as determined by IHC. She has also proposed a HER2 testing algorithm based on the endometrial serous carcinoma. It is important to note that these studies all use a variety of platforms, reagents, and cut-off scoring systems making it difficult to apply the results in an Australian setting. Moreover, in our laboratory, we have been using Dual in situ hybridisation (DISH) for assessing HER2 in breast and gastric cancers and not FISH. As such, our team aims to validate HER2 FISH testing for endometrial serous carcinoma. Acknowledgement: We thank Dr Natalia Buza, Yale School of Medicine for providing external tissue, endometrial serous carcinoma. This project has been funded by PathWest, Chief Pathologist Early Career Research Award 2022, with an amount of $10,000. References 1. Robinson CL, Harrison BT, Ligon AH, et al. Detection of ERBB2 amplification in uterine serous carcinoma by next-generation sequencing: an approach highly concordant with standard assays. Mod Pathol 2021; 34: 603–12. 2. Erickson BK, Zeybek B, Santin AD, et al. Targeting human epidermal growth factor receptor 2 (HER2) in gynecologic malignancies. Curr Opin Obstet Gynecol 2020; 32: 57–64. 3. Fader AN, Roque DM, Siegel E, et al. Randomized phase II trial of carboplatin-paclitaxel compared with carboplatin-paclitaxel-trastuzumab in advanced (stage III-IV) or recurrent uterine serous carcinomas that overexpress Her2/Neu (NCT01367002): updated overall survival analysis. Clin Cancer Res 2020; 26: 3928–35.