Abstract 1180: Estimating the contribution of epidemiologic risk factors to racial differences in epithelial ovarian cancer incidence
Authors: Peres Lauren C. , Camacho Tareq F. , Bandera Elisa V. , Bethea Traci N. , Joslin Charlotte E. , Wu Anna H. , Beeghly-Fadiel Alicia , Cloyd Emily K. , Harris Holly R. , Moorman Patricia G. , Myers Evan , Ochs-Balcom Heather M. , Rosenow Will L. , Setiawan Veronica W. , Rosenberg Lynn , Schildkraut Joellen M. 
Published: September 2020

Abstract
Purpose. Although the incidence of epithelial ovarian cancer is highest among non-Hispanic white women, African-American women have the worst survival of all racial/ethnic groups. We hypothesize that differences in the prevalence of known and suspected ovarian cancer risk factors may explain a portion of the differences in incidence of epithelial ovarian cancer between white and African-American women.
Methods. We used data from seven U.S. studies in the Ovarian Cancer in Women of African Ancestry (OCWAA) consortium, the North Carolina Ovarian Cancer Study (NCOCS), the Los Angeles Ovarian Cancer Study (LACOCS), the African-American Cancer Epidemiology Study (AACES), the Cook County Case-Control Study (CCCCS), the Black Women's Health Study (BWHS), the Women's Health Initiative (WHI), and the Multiethnic Cohort Study (MEC). The association between each known or suspected ovarian cancer risk factor (age, parity, oral contraceptive use, tubal ligation, body mass index (BMI), family history of ovarian and breast cancer, menopausal status, education, hysterectomy, aspirin use, talcum powder applied to genital areas, endometriosis, and age at menarche) was estimated using logistic regression with study site interactions to capture heterogeneity across studies. Using the Bruzzi method, population attributable risks (PAR) were calculated by race for each risk factor individually and collectively for all risk factors.
Results. The comparison of 3,249 white ovarian cancer cases and 9,650 controls to 1,054 African-American cases and 2,410 controls revealed notable differences in the PAR of several risk factors by race. African-American women had a statistically significantly higher PAR for family history of breast cancer and BMI ≥30kg/m2compared to white women (10.0% vs. 2.5% and 8.9% vs. 0.4%, respectively). Although not statistically significant, white women had a higher PAR for oral contraceptive use (duration &lt;5 years) and not having had a tubal ligation than African-American women. When evaluating all risk factors collectively, the overall PAR was 63.9% for African-American women and 48.0% for white women. We also calculated overall PARs excluding WHI due to differences in the inclusion criteria for WHI compared to the other population-based studies in OCWAA: 65.7% for African-American women and 57.8% for white women.
Conclusions. Our findings suggest that the known and suspected ovarian cancer risk factors investigated in this study may be partially responsible for differences in ovarian cancer incidence between white and African-American women. Although important across both racial groups, collectively, the factors studied accounted for slightly more of the ovarian cancer risk among African-American women than white women.
Citation Format: Lauren C. Peres, Tareq F. Camacho, Elisa V. Bandera, Traci N. Bethea, Charlotte E. Joslin, Anna H. Wu, Alicia Beeghly-Fadiel, Emily K. Cloyd, Holly R. Harris, Patricia G. Moorman, Evan Myers, Heather M. Ochs-Balcom, Will L. Rosenow, Veronica W. Setiawan, Lynn Rosenberg, Joellen M. Schildkraut. Estimating the contribution of epidemiologic risk factors to racial differences in epithelial ovarian cancer incidence [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1180.