David S. Hong

Background: We aimed to describe RAS mutations in gynecologic cancers as they relate to clinicopathologic and genomic features, survival, and therapeutic implications. Methods: Gynecologic cancers with available somatic molecular profiling data at our institution between February 2010 and August 2022 were included and grouped by RAS mutation status. Overall survival was estimated by Kaplan-Meier method, and multivariable analysis was performed using Cox proportional-hazards model. Results: Of 3328 gynecologic cancers, 523 (15.7%) showed any RAS mutation. Patients with RAS-mutated tumors were younger (57 vs 60 years non-mutated), had higher prevalence of endometriosis (27.3% vs 16.9%), and lower grades (grade 1/2, 43.2% vs 8.1%, all p<0.0001). Highest prevalence of KRAS mutation was in mesonephric-like endometrial (100%, n=9/9), mesonephric-like ovarian (83.3%, n=5/6), mucinous ovarian (60.4%), and low-grade serous ovarian (44.4%) cancers. After adjustment for age, cancer type, and grade, RAS mutation was associated with worse overall survival (HR=1.3, p=0.001). Specific mutations were in KRAS (13.5%), NRAS (2.0%), and HRAS (0.51%), most commonly KRAS G12D (28.4%) and G12V (26.1%). Common co-mutations were PIK3CA (30.9%), PTEN(28.8%), ARID1A (28.0%), and TP53 (27.9%), of which 64.7% were actionable. RAS+MAPK pathway-targeted therapies were administered to 62 patients with RAS-mutated cancers. While overall survival was significantly higher with therapy (8.4 years [95%CI 5.5-12.0] vs 5.5 years [95%CI 4.6-6.6], HR=0.67, p=0.031), this effect did not persist in multivariable analysis. Conclusion: RAS mutations in gynecologic cancers have a distinct histopathologic distribution and may impact overall survival. PIK3CA, PTEN, and ARID1A are potentially actionable co-alterations. RAS pathway-targeted therapy should be considered.