Abstract C105: Racial differences in the association of endometriosis and fibroids with risk of ovarian cancer
Authors: Harris Holly , Peres Lauren , Johnson Courtney , Guertin Kristin , Beeghly-Fadiel Alicia , Bandera Elisa , Bethea Traci , Joslin Charlotte , Wu Anna , Moorman Patricia , Ochs-Balcom Heather , Petrick Jessica , Setiawan Veronica , Rosenberg Lynn , Schildkraut Joellen , Myers Evan 
Published: January 2023

PURPOSE: Women with endometriosis have a 2 to 3-fold greater risk of endometrioid and clear cell ovarian cancer than other women, based on estimates from studies predominantly of White women. Fibroids have not been consistently associated with ovarian cancer risk but are the most common indication for hysterectomies in the U.S. Hysterectomy has been associated with lower ovarian cancer risk in subgroups of women including those with fibroids; thus fibroids may indirectly impact ovarian cancer risk. We evaluated the association of endometriosis and fibroids with ovarian cancer risk among Black and White women, taking into consideration the impact of hysterectomy. METHODS: We used data from six studies in the Ovarian Cancer in Women of African Ancestry (OCWAA) consortium. Participants included 2,995 Black women and 5,281 White women. Logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for the association between endometriosis and fibroids with ovarian cancer risk, overall, by race, and stratified by histotype. We also assessed effect modification by hysterectomy. RESULTS: Overall the prevalences of endometriosis and fibroids were 6.4% and 43.2% among Black women and 7.0% and 21.5% among White women, respectively. Endometriosis was associated with an increased risk of endometrioid and clear cell ovarian cancer in Black and White women. Among Black women the association was strongest for endometrioid tumors (OR=7.06; 95% CI=3.86-12.91) compared to White women (OR=2.17; 95% CI=1.36-3.45) with a significant difference by race (phetereogeneity=0.003). When stratified by hysterectomy the association between endometriosis and ovarian cancer risk in White women was stronger in those who did not report a hysterectomy. However, in Black women, the elevated risk of ovarian cancer among women with endometriosis was present among those with and without hysterectomy. Fibroids were associated with a slightly elevated risk of ovarian cancer in Black (OR=1.34; 95% CI=1.11-1.62) and White women (OR=1.22; 95% CI=1.05-1.41). For both groups, the association was present only in those who did not report a hysterectomy. Black women who had a history of fibroids and no hysterectomy had a 53% greater odds of ovarian cancer (95% CI=1.23-1.89) compared to those without fibroids, while there was no association with fibroids in the hysterectomy group (OR=0.92, 95% CI=0.62-1.36) (pinteraction=0.05). A similar pattern was observed among White women, but the interaction was not significant (pinteraction=0.21). CONCLUSION: Both Black and White women with endometriosis had a higher risk of ovarian cancer, and hysterectomy modified this association only among White women. Fibroids were associated with modestly increased risk of ovarian cancer among Black and White women, with hysterectomy modifying the risk in both groups. Further research is needed to understanding how racial differences in diagnoses of these conditions, and differential access to care and treatment options, impact or modify ovarian cancer risk.

Citation Format: Holly Harris, Lauren Peres, Courtney Johnson, Kristin Guertin, Alicia Beeghly-Fadiel, Elisa Bandera, Traci Bethea, Charlotte Joslin, Anna Wu, Patricia Moorman, Heather Ochs-Balcom, Jessica Petrick, Veronica Setiawan, Lynn Rosenberg, Joellen Schildkraut, Evan Myers. Racial differences in the association of endometriosis and fibroids with risk of ovarian cancer [abstract]. In: Proceedings of the 15th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2022 Sep 16-19; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr C105.