Abstract PO-180: Genital powder use and risk of epithelial ovarian cancer in the Ovarian Cancer in Women of African Ancestry Consortium

PURPOSE: To date, the epidemiology of epithelial ovarian cancer (EOC) among African-American women has been severely understudied. It remains unclear to what extent variation in the prevalence of EOC risk factors may explain incidence disparities between African-American and white women. Genital powder use is more common among African-American women; however, studies of genital power use and EOC risk have been conducted predominantly in white populations, and histotype specific analyses among African-American populations are limited. The objective of this study was to evaluate the association between genital powder use and EOC risk among African-American and white women, overall and by histotype.

METHODS: We used data from four ovarian cancer case-control studies in the Ovarian Cancer in Women of African Ancestry (OCWAA) consortium: the African American Cancer Epidemiology Study, the Los Angeles County Ovarian Cancer Study, the Cook County Case-Control Study, and the North Carolina Ovarian Cancer Study. Participants included 601 African-American cases, 1,012 African-American controls, 2,225 white cases, and 3,086 white controls who answered questions on genital powder use prior to 2014. The association between genital powder use and EOC risk was estimated using logistic regression. Pooled histotype specific odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated using polytomous logistic regression. The population attributable risk (PAR) by race was calculated using the Bruzzi method. RESULTS: The prevalence of reporting ever genital powder use was 66% among African-American women and 44% among white women. African- American women who ever used genital powder were 29% more likely to develop EOC compared to African-American women who reported no use (OR=1.29, 95% CI=0.98-1.71). White women who ever used genital powder were 36% more likely to develop EOC compared to white women reporting no use (OR=1.36, 95% CI=1.12- 1.52). The associations were similar when examined by histotype. Among African- American women, the ORs were 1.29 (95% CI=0.94-1.76) for high grade serous (HGS) and 1.38 (95% CI=0.87-2.19) for non-HGS. For white women, the corresponding ORs were 1.27 (95% CI=1.06-1.52) and 1.21 (95% CI=0.96-1.56), respectively. The PAR for genital powder use was slightly higher, but not statistically significantly different, in African-American women (PAR=10.7, 95% CI=3.7-17.5) compared to white women (PAR=7.8, 95% CI=4.9-10.7). CONCLUSION: While the prevalence of ever genital body powder use was higher among African-American women, the associations between genital powder use and ovarian cancer risk were similar between African-American and white women, and did not materially vary by histotype. Further analyses incorporating additional OCWAA studies and using more refined exposure categories (e.g., frequency and duration of powder use, age at first application) are currently being conducted.

Citation Format: Colette P. Davis, Elisa V. Bandera, Traci N. Bethea, Tareq F. Camacho, Charlotte E. Joslin, Anna H. Wu, Alicia Beeghly-Fadiel, Emily K. Cloyd, Patricia G. Moorman, Evan Myers, Heather M. Ochs-Balcom, Lauren C. Peres, Will L. Rosenow, Veronica W. Setiawan, Lynn Rosenberg, Joellen M Schildkraut, Holly R. Harris. Genital powder use and risk of epithelial ovarian cancer in the Ovarian Cancer in Women of African Ancestry Consortium [abstract]. In: Proceedings of the AACR Virtual Conference: Thirteenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2020 Oct 2-4. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(12 Suppl):Abstract nr PO-180.

Abstract 1180: Estimating the contribution of epidemiologic risk factors to racial differences in epithelial ovarian cancer incidence

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 <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.