Abstract C070: Racial disparities in body mass index and ovarian cancer risk in the OCWAA Consortium

Abstract

Abstract Objective: Obesity disproportionately affects African American (AA) women, and there is some suggestion that its association with ovarian cancer risk may be stronger among AA compared to white women, but no study to date has been adequately powered to compare risk between the two populations. The Ovarian Cancer in Women of African Ancestry (OCWAA) Consortium provided a unique opportunity to evaluate the association between body mass index (BMI) and invasive epithelial ovarian cancer (EOC) risk in AA and white women and to estimate the contribution of obesity to ovarian cancer risk in both racial groups. Methods: The OCWAA Consortium is a collaboration of six of the largest epidemiologic studies of ovarian cancer in the United States that include AA women: four case-control and two case-control studies nested within cohort studies. The six studies are the Chicago Case-Control Study, the North Carolina Ovarian Cancer Study, the Los Angeles Ovarian Cancer Case-Control Studies, the African American Cancer Epidemiology Study, the Black Women’s Health Study, and the Multiethnic Cohort. BMI before diagnosis was available in all the studies and data on BMI and relevant confounders were harmonized for analyses. There were 1,144 AA cases, 2,910 AA controls, 3,174 white cases, and 9,160 white controls included. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were computed using random-effects multi-level logistic regression models separately by race and histotype with control for relevant covariates, which included study, age, education, parity, oral contraceptive use, age at menarche and family history of breast/ovarian cancer. Multinomial regression was used for histotype analyses. Population attributable risk (PAR) estimates were computed by race and histotype. Results: The prevalence of obesity (BMI≥30 kg/m2) was higher in AAs compared to white women for both cases (53.2% vs 21.4%) and controls (45.7% vs. 18.4%). For EOC, there was little evidence of an association with obesity for white women. For AAs, risk was elevated for BMI≥30 kg/m2 (ORBMI 30-34=1.37, 95% CI: 1.12, 1.69; ORBMI≥35 = 1.26, 95% CI: 0.74, 2.15) relative to BMI 18.5-<25 kg/m2. There was an elevated risk for non-high-grade serous EOC for both AA and white women (for AA women, ORBMI 30-34=1.67, 95% CI: 1.14, 2.44 and ORBMI≥35 = 1.76; 95% CI: 0.84, 3.69; for white women, ORBMI ≥35 = 1.39; 95% CI: 1.06, 1.82), but not for high-grade serous EOC. The PAR for BMI≥30 was 7.1% (95% CI: 2.4, 15.6) for AAs and 2.6% (95% CI: -0.3, 5.4) for whites for all EOC. For non-high-grade serous EOC, the PAR was 16.5% (95% CI: 3.4, 28.2) for AAs and 6.4% (95% CI: 2.2, 10.3) for whites. Conclusions: Obesity was a contributor to overall EOC risk among AA women but not among white women. Obesity did not contribute to the risk of high-grade serous EOC for AAs or whites, but it was associated with non-high-grade serous cases among both AA and white women. The association with non-high-grade serous EOC was greater among AAs than whites. Citation Format: Elisa V Bandera, Fabian Camacho, Deanna Chyn, Emily K Cloyd, Traci N Bethea, Alicia Beeghly-Fadiel, Charlotte E Joslin, Evan Myers, Patricia G Moorman, Heather M Ochs-Balcom, Holly R Harris, Lauren C Peres, Veronica Wendy Setiawan, Anna H Wu, Lynn Rosenberg, Joellen M Schildkraut. Racial disparities in body mass index and ovarian cancer risk in the OCWAA Consortium [abstract]. In: Proceedings of the Twelfth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2019 Sep 20-23; San Francisco, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl_2):Abstract nr C070.