In this episode of the Journal of Gynecologic Oncology podcast, we delve into a study examining the prognostic significance of HER2 expression in uterine carcinosarcoma (UCS), a rare and aggressive endometrial cancer. Conducted by Mizoguchi et al., the research analyzes HER2 status in 148 UCS patients using immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) testing. The findings reveal that in early-stage UCS, HER2-negative or low expression is associated with poorer overall survival compared to high HER2 expression, indicating that HER2 IHC scoring could be a valuable prognostic marker in early-stage disease. However, in advanced stages, HER2 status does not correlate with survival outcomes. The study underscores the potential of HER2-targeted therapies, particularly in early-stage UCS, and suggests that IHC alone may be sufficient for UCS prognostication. Tune in to explore the implications of these findings for future treatment strategies.