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Background: Douching is associated with disorders involving genital tract inflammation and genital talc use with epithelial ovarian cancer (EOC), but their joint effects are infrequently considered. Methods: From 2,040 cases of EOC and 2,100 controls enrolled in eastern Massachusetts and New Hampshire, we used unconditional logistic regression to estimate risk for EOC associated with douching and/or talc use. In subsets of cases and controls, we also collected information about pelvic inflammatory disease (PID), ectopic pregnancy, and cervical neoplasia to estimate risk for these events from douching and/or talc use. Results: The adjusted OR and 95% confidence interval (CI) for all EOC was 0.94 (0.76–1.16) in women who douched but never used talc and 1.28 (1.09–1.51) in women who used talc but never douched. Compared with women who never regularly douched or used talc, ORs (95% CIs) were 0.83 (0.52–1.33) for women who both used talc and homemade douches and 1.53 (1.11–2.10) for women who both used talc and store-bought douches. Cases who both douched and used talc were more likely to have had PID compared with cases who had used neither [OR = 5.03 (95% CI, 1.61–15.7)]. Conclusions: Douching is not an independent risk factor for ovarian cancer, but the combination of talc use and store-bought douches may modestly increase the risk for EOC beyond that for talc use alone. Impact: The joint effect of talc use and douching, especially with commercial products, should be considered in evaluating risks associated with disorders involving genital tract inflammation or EOC.

Genital powder use has been associated with risk of epithelial ovarian cancer in some, but not all, epidemiologic investigations, possibly reflecting the carcinogenic effects of talc particles found in most of these products. Whether risk increases with number of genital powder applications and for all histologic types of ovarian cancer also remains uncertain. Therefore, we estimated the association between self-reported genital powder use and epithelial ovarian cancer risk in eight population-based case–control studies. Individual data from each study were collected and harmonized. Lifetime number of genital powder applications was estimated from duration and frequency of use. Pooled ORs were calculated using conditional logistic regression matched on study and age and adjusted for potential confounders. Subtype-specific risks were estimated according to tumor behavior and histology. 8,525 cases and 9,859 controls were included in the analyses. Genital powder use was associated with a modest increased risk of epithelial ovarian cancer [OR, 1.24; 95% confidence interval (CI), 1.15–1.33] relative to women who never used powder. Risk was elevated for invasive serous (OR, 1.20; 95% CI, 1.09–1.32), endometrioid (OR, 1.22; 95% CI, 1.04–1.43), and clear cell (OR, 1.24; 95% CI, 1.01–1.52) tumors, and for borderline serous tumors (OR, 1.46; 95% CI, 1.24–1.72). Among genital powder users, we observed no significant trend (P = 0.17) in risk with increasing number of lifetime applications (assessed in quartiles). We noted no increase in risk among women who only reported nongenital powder use. In summary, genital powder use is a modifiable exposure associated with small-to-moderate increases in risk of most histologic subtypes of epithelial ovarian cancer. Cancer Prev Res; 6(8); 811–21. ©2013 AACR.