KRAS-mutant mesonephric-like ovarian adenocarcinoma shows 17.5-mo median PFS and “cotton candy” ultrasound signature

Mesonephric-like adenocarcinoma (MLA) is a rare ovarian carcinoma subtype (WHO 2020) that appears molecularly KRAS-driven; in this prospective, single-center observational series (Jan 2020–Dec 2023), 14/467 ovarian cancers (3.0%) were MLA (mean age 60 years), often with endometriosis (64.2%) and mixed histology (55.6%). Most presented FIGO III–IV (57.1%); 78.5% had upfront surgery with complete cytoreduction in 92.8%, yet median PFS was 17.5 months (IQR 13.5–35.9) with 57.1% recurrence (predominantly peritoneal), while median OS was not reached (1 death). For context, advanced epithelial ovarian cancer treated with carboplatin/paclitaxel historically yields median PFS ~12 months, and adding bevacizumab through maintenance extended PFS to ~18 months in GOG-0218—so this MLA PFS sits in the “bevacizumab-era” range despite excellent cytoreduction, underscoring biology-driven relapse risk.