Abstract 7377: Intrauterine device use and ovarian cancer risk among 11 case-control studies and 7 prospective cohort studies

Abstract Introduction: Recently, intrauterine device (IUD) use has increased and oral contraceptive (OC) use has decreased. While OC use is known to reduce epithelial ovarian cancer (EOC) risk, previous studies of IUD use and EOC risk have shown inconsistent associations. Here, we examined the association between primarily non-hormonal IUD use and EOC risk by leveraging harmonized individual-level data from 11 case-control studies, 10 in the Ovarian Cancer Association Consortium and the African American Cancer Epidemiology Study, and 7 prospective cohort studies from the Ovarian Cancer Cohort Consortium. Methods: Contraception use was self-reported through questionnaires. Study-specific odds ratios (OR) and 95% confidence intervals (CI) were estimated using unconditional logistic regression (case-control studies) or time varying polytomous logistic regression models (cohort studies), adjusted for age, duration of OC use, parity, and family history of breast or ovarian cancer. Heterogeneity between studies was assessed for case-control and cohort studies separately using Cochran Q. There was no evidence of heterogeneity between studies, thus, data were pooled within each study design. Case-control and cohort pooled results were combined by random effects meta-analysis. Associations were estimated for overall EOC risk and by histotype (high-grade serous, low-grade serous, endometrioid, clear cell, mucinous). Heterogeneity across histotypes was evaluated using a Wald test for case-control and cohort models separately. Results: Among case-control studies, data were pooled for 11, 033 cases and 13, 358 controls. A total of 1, 933 (17.5%) cases reported ever IUD use compared to 2, 656 (19.9%) controls. Among cohort studies, data were pooled for 629, 008 participants with 3, 549 incident cases. A total of 72, 546 (11.5%) participants reported ever IUD use at enrollment. The associations of ever vs. never IUD use and EOC risk were similar in case-control (pooled OR: 0.92; 95% CI: 0.86-0.98) and cohort studies (pooled OR: 1.00; 95% CI: 0.88-1.13). When meta-analyzed, there was a suggestive 5% lower odds of overall EOC among IUD users (OR: 0.94; 95% CI: 0.88-1.01; p-het = 0.26). We observed heterogeneity by histotype in case-control studies (p=0.0001) but not in cohort studies (p=0.77). After meta-analysis, results suggested that IUD use was associated with a lower risk of mucinous (OR: 0.85; 95% CI: 0.73-0.98), clear cell (OR: 0.69; 95% CI: 0.64-0.86), and low grade serous EOC (OR: 0.75; 95% CI: 0.55-1.01). Conclusion: IUD use was not associated with an increased risk of EOC in this analysis of over 12, 000 ovarian cancer cases. Our findings suggest there may be an inverse association between IUD use and risk of mucinous, clear cell, and low grade serous EOC. Analyses are ongoing and will include assessment of effect modification by parity and birth cohort, as well as consideration of timing of IUD use. Citation Format: Jennifer M. Mongiovi, Ana Babic, Allison F. Vitonis, Naoko Sasamoto, Mark K. Townsend, Brett M. Reid, Mollie E. Barnard, Holly R. Harris, Lauren Peres, Britton Trabet, Brooke L. Fridley, Katie M. O'Brien, Anita Koushik, Renee Turzanski Fortner, Jennifer A. Doherty, Joelle M. Schildkraut, Shelley S. Tworoger, Kathryn L. Terry, Ovarian Cancer Association Consortium, Ovarian Cancer Cohort Consortium. Intrauterine device use and ovarian cancer risk among 11 case-control studies and 7 prospective cohort studies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 7377.