Racial and ethnic disparities in severe chemotherapy-related toxicities among women with ovarian cancer: Findings from the KPROCS cohort study.

245 Background: Chemotherapy remains a cornerstone of ovarian cancer treatment, but associated toxicities can substantially impact patients’ quality of life, adherence, and survival. Severe toxicities may lead to dose reductions, treatment delays, or early discontinuation, compromising treatment efficacy. Although racial and ethnic disparities in guideline-concordant care and survival after ovarian cancer are well documented, differences in the burden of chemotherapy-related toxicities remain poorly understood. Identifying such disparities is essential for equitable care and targeted supportive interventions. Methods: We examined racial and ethnic differences in chemotherapy-related toxicities among 4,739 women in the Kaiser Permanente Research on Ovarian Cancer Survival (KPROCS) cohort study, diagnosed with epithelial ovarian cancer between 2000–2022 and treated at Kaiser Permanente Northern California. Women were included if they were ≥18 years and resided in California at diagnosis, and received chemotherapy. Toxicities—anemia, neutropenia, thrombocytopenia, hepatic and renal impairment, and neuropathy—were identified via Common Terminology Criteria for Adverse Events (CTCAE) v5.0, with grade ≥3 classified as severe. Multivariable logistic regression estimated the association between race and ethnicity and severe toxicity, adjusting for age, stage, histotype, body mass index, Charlson comorbidity index, and chemotherapy administration schedule (dose-dense vs. standard). Results: The cohort included 272 Black, 629 Hispanic, 711 Non-Hispanic Asian, and 3,127 non-Hispanic White (NHW) women. Over 90% received a platinum/taxane regimen, with similar rates across groups. Black women were more likely to receive dose-dense regimens compared with NHW women (25% vs. 17%). Overall, 42% of patients experienced severe toxicities. Black women experienced statistically significantly higher rates of severe hematologic (53%) and any severe toxicities (55%) compared with NHW women (39% and 41%, respectively). In multivariable models, compared with NHW women, Black women had increased odds of severe toxicity (OR: 1.55, 95% CI: 1.17–2.07), particularly of severe hematologic toxicity (OR: 1.65; 95% CI: 1.24–2.20). Multivariable models did not reveal statistically significant differences in severe toxicities between Hispanic or Non-Hispanic Asian women compared to NHW women. Conclusions: Black women experienced a disproportionately higher burden of chemotherapy-related toxicities compared with other racial and ethnic groups. These findings underscore the need to investigate biological, clinical, and system-level contributors to toxicity risk, and to evaluate whether toxicities mediate the persistent survival disparities in ovarian cancer.