Impact of HER2 assessment by CISH in urothelial carcinoma: A retrospective single-center experience

Background: In recent years, HER2 amplification has been evaluated as a potential prognostic biomarker and therapeutic target in urothelial carcinoma (UC). In this retrospective study, we aimed at exploring the prognostic role of HER2 amplification in UC, measured by chromogenic in situ hybridization (CISH). Methods: We retrospectively evaluated the presence of HER2 amplification by using CISH in 31 UC patients followed at a single institution between 2018 and 2020. The primary objective was to assess the frequency of HER2 amplification and to compare clinical outcomes of HER2-amplified patients with non-amplified UCs. Results: HER2 amplification was identified in 4 out of 31 patients (12.9 %). After a median follow-up of 28.1 months (95 % Confidence Intervals [CI] 11.2?45.1), median overall survival (OS) in the whole population was 10.9 months (95 % CI 3.5?22.1). Despite not reaching statistical significance, median OS was shorter in HER2amplified patients (6.8 months, 95 % CI 3.9?9.7) compared to HER2-negative UCs (15.4 months, 95 % CI 7.5?23.3) (p = 0.45). Conclusions: Although limited by the small sample size, the results of our study suggest that HER2 amplifications by CISH could represent a prognostic factor for shorter survival in UC patients.