Background: The Ovarian Cancer in Women of African Ancestry consortium (OCWAA) was established to address racial disparities in epithelial ovarian cancer (EOC) risk and survival. Specifically, we aim to estimate the degrees to which racial differences in incidence and survival of EOC between African-American (AA) and white women are attributable to differences in the prevalence and timing of risk factors and in the magnitude of risk associations.

Methods: OCWAA includes four case-control studies (the African-American Cancer Epidemiology Study, the North Carolina Ovarian Cancer Study, the Los Angeles County Ovarian Cancer Study, and the Cook County Case-Control Study) and two nested case-control studies within cohort studies (the Black Women's Health Study and the Multiethnic Cohort Study). A centralized core database consisting of demographic and epidemiologic risk factors for borderline and invasive EOC, tumor characteristics and prognostic factors has been created, and the majority of data has been harmonized across studies. A histotype classification scheme was uniformly applied using a combination of morphology and grade information to best represent the most recent diagnostic guidelines for ovarian cancer as detailed in the 2014 WHO Classification of Tumors of the Female Reproductive System.

Results: A total of 1,169/2,324 AA cases and controls and 2,963/3,934 white cases and controls have been included in the OCWAA database to date. Approximately 83% of cases are invasive EOC, 15% are borderline tumors, and 2% are missing tumor behavior information. Among the invasive EOC cases, 61% are high-grade serous carcinomas. The average age at diagnosis of EOC cases is the same in AA and white women (57.2 years), and the year of diagnosis ranges from 1991 to 2016. The following risk factors showed marked prevalence differences in AA and white controls: obesity (46.3% vs 19.2%), breastfeeding (42.7% vs 54.3%), tubal ligation (31.1% vs 17.9%), postmenopausal hormone use (23.8% vs 40.8%), nulliparity (14.9% vs 19.2%), at least a college degree (35.5% vs 56.4%), and menarche age <13 (51.6% vs 47.4%; p<.01); p<.0001 for all except where noted. In preliminary EOC risk analyses, we observed positive associations with body mass index and nulliparity and inverse associations with tubal ligation, oral contraceptive use and breastfeeding in both AA and white women. The harmonization of other factors including duration, frequency and timing of key risk factors, physical activity, comorbidities, medication use, and treatment information is ongoing.

Conclusions: OCWAA represents the largest study investigating disparities in ovarian cancer risk and survival between AA and white women. This consortium is uniquely positioned to study the epidemiology of ovarian cancer in AA, focusing on the role of lifestyle and behavioral characteristics, reproductive risk factors, treatment and other prognostic factors in explaining racial differences in ovarian cancer incidence and survival.

This abstract is also being presented as Poster C083.

Citation Format: Veronica Wendy Setiawan, Lauren Peres, Lynn Rosenberg, Traci Bethea, Patricia Moorman, Evan Myers, Anna Wu, Charlotte Joslin, Elisa Bandera, Deanna Chyn, Fabian Camacho, Joellen Schildkraut. Investigating the determinants of racial disparities in ovarian cancer incidence: The OCWAA consortium [abstract]. In: Proceedings of the Eleventh AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2018 Nov 2-5; New Orleans, LA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl):Abstract nr PR16.