Current diagnostic guidelines and perpetuation of inequities in ovarian cancer: A National Cancer Database study.

11027 Background: International guidelines use cancer antigen 125 (CA-125) thresholds to recommend which patients with pelvic masses should undergo evaluation by gynecologic oncologists for ovarian cancer and which patients can be observed without intervention. However, CA-125 thresholds were developed from white populations, and CA-125 levels have been shown to be 10-29% lower in healthy Black women than white women. If CA-125 levels also differ among patients with cancer, current guidelines may contribute to missed or delayed ovarian cancer diagnoses among Black women. Our objective was to examine CA-125 levels at cancer diagnosis by patient race and associations of CA-125 elevation with timely treatment. Methods: We conducted a retrospective cohort study of patients with ovarian cancer ages 0 to 90+ years diagnosed from 2018-2020 using the National Cancer Database. CA-125 was defined as positive/borderline or negative/normal by each site. We report descriptive CA-125 elevated by patient characteristics. We use multivariate logistic regression models to examine the association of patient characteristics with CA-125 level overall and for epithelial and high-grade serous cancers. We used generalized linearized models to examine the association of CA-125 with days from diagnosis to chemotherapy start for patients with Stage II-IV disease. Results: Of 38,707 patients diagnosed with ovarian cancer and with reported CA-125, 13.4% of patients did not have an elevated CA-125 at diagnosis. Patients who identified as Black, Asian, or Hispanic were less likely to have an elevated CA-125 at ovarian cancer diagnosis as were patients with early-stage disease. Among patients with high-grade serous cancer (n=18,151), 8% of Black patients had normal CA-125 at diagnosis compared to 6% of white patients. In multivariate analyses, being Black remained associated with lower odds of elevated CA-125 (OR 0.71, 95%CI 0.63-0.81), after adjustment for menopausal status, comorbidities, and stage. Even among patients with high-grade serous ovarian cancer, being black was associated with lower odds of having an elevated CA-125 (OR 0.78, 95%CI 0.64-0.96). Patients with Stage II-IV ovarian cancer who had a normal CA-125 at diagnosis had 12 days longer on average to chemotherapy initiation compared to patients with elevated CA-125. Conclusions: Current thresholds for CA-125 and gynecologic oncology referral likely miss Black patients with ovarian cancer and may delay timely treatment. Work is needed to develop inclusive CA-125 thresholds and guidelines for ovarian cancer diagnosis and not compound disparities.