Homologous recombination deficiency and survival in ovarian high-grade serous carcinoma by self-reported race

Background: Half of ovarian high-grade serous carcinomas (HGSC) have homologous recombination deficiency (HRD). However, HRD is not well-characterized in Black individuals who experience worse survival after a diagnosis of HGSC. The objective of this study was to characterize ovarian HGSC HRD and examine its association with survival by self-reported race. Methods: HRD features were identified using matched tumor-normal whole-exome and RNA sequencing in a HGSC cohort. We calculated age and stage-adjusted hazard ratios (HR) and 95% confidence intervals (CIs) for survival, comparing individuals with a feature to those without, separately by self-reported race. Results: Any HRD was associated with a 32% reduced risk of death in Black individuals compared with a 62% reduction in White individuals (Black HR=0.68, 95%CI 0.43–1.09; White HR=0.38, 95%CI 0.14–1.04). More of the germline and somatic variants detected among Black individuals were unannotated or variants of uncertain significance (VUS; germline 65% versus 45%; somatic 62% versus 50%, respectively). Black individuals with germline unannotated/VUS were more likely to have tumors with HRD scarring and a first-degree family history of breast or ovarian cancer compared with those without (HRD scar 71.4% versus 49.6%; family history 68.4% versus 34.6%). Conclusions: HRD testing informs precision-based medicine approaches that improve outcomes, but a higher proportion of VUS among Black individuals may complicate referral for such care leading to worse outcomes for Black individuals. Impact: Our findings emphasize the importance of recruiting diverse individuals in genomics research and better characterizing VUS.