Epithelial ovarian cancer survival by race/ethnicity in an equal-access healthcare population.

Abstract

e18525 Background: Previous studies in the general population have observed that compared with Non-Hispanic White (NHW) women, Pacific Islander (PI) and Non-Hispanic Black (NHB) women have higher age-adjusted mortality rates from epithelial ovarian cancer (EOC), while Asian Americans (AS) have lower mortality. It is unknown whether these patterns reflect biological differences, environmental exposure or perhaps access to care. Our objective was to investigate whether self-reported race/ethnicity is associated with differences in EOC survival in a Military population where patients have equal access to healthcare. Methods: The study population included women diagnosed with EOC (ovarian, fallopian tube and primary peritoneal cancers) among US Department of Defense beneficiaries reported in the Automated Central Tumor Registry Database (year of diagnosis range: 2001-18). Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using Cox proportional hazards regression models following participants from their date of diagnosis until last contact or censoring, whichever occurred first. Multivariable models were adjusted for covariates selected a priori because of their known influence on risk of EOC death; age at diagnosis (continuous), histology, stage and receipt of the first course of chemotherapy treatment. We adjusted for year of diagnosis (continuous) to account for possible changes in treatment over time. Results: The study population included 1151 patients diagnosed with EOC: 796 NHW, 111 NHB, 130 AS, 49 PI and 65 Hispanic (HS). All EOC patients had complete information on age at diagnosis, stage and chemotherapy treatment. During a median (interquartile range) follow-up of 3.5 years (1.8-6.7), 702 EOC patients (61%) died of all causes. When comparing crude EOC patient characteristics by racial/ethnic group, NHW had the highest frequency of EOC leading to death (58% vs. < 49% in other groups). There also were differences in histology; NHW and NHB had a higher frequency of serous tumors ( > 56% of EOCs vs. < 52% in other groups); PI had a high proportion of endometrioid histology (14% of EOCs vs. < 11% in others); 10% of EOCs among AS had clear cell histology (vs. < 9% in others). HS had a high percentage of local disease (23% vs. < 20% in others). In multivariable survival analysis adjusting for clinical factors, we observed that compared with NHW, there were no differences in EOC survival by race/ethnicity: AS, HR = 0.80 (95% CI = 0.61-1.05); NHB, HR = 0.96 (95% CI = 0.72-1.28); PI, HR = 0.92 (95% CI = 0.58-1.46); and HS, HR = 0.82 (95% CI = 0.56-1.21). Conclusions: We observed no racial/ethnic disparities in EOC survival in a Military equal access treatment environment. These results highlight the importance of studying how differences in access to healthcare may impact observed racial/ethnic disparities for EOC.