Association of Powder Use in the Genital Area With Risk of Ovarian Cancer

Abstract

Importance: The relationship between use of powder in the genital area and ovarian cancer is not established. Positive associations reported in case-control studies have not been confirmed in cohort studies.

Objective: To estimate the association between use of powder in the genital area and ovarian cancer using prospective observational data.

Design, setting, and participants: Data were pooled from 4 large, US-based cohorts: Nurses' Health Study (enrollment 1976; follow-up 1982-2016; n = 81 869), Nurses' Health Study II (enrollment 1989; follow-up 2013-2017; n = 61 261), Sister Study (enrollment 2003-2009; follow-up 2003-2017; n = 40 647), and Women's Health Initiative Observational Study (enrollment 1993-1998; follow-up 1993-2017; n = 73 267).

Exposures: Ever, long-term (≥20 years), and frequent (≥1/week) use of powder in the genital area.

Main outcomes and measures: The primary analysis examined the association between ever use of powder in the genital area and self-reported incident ovarian cancer. Covariate-adjusted hazard ratios (HRs) and 95% CIs were estimated using Cox proportional hazards models.

Results: The pooled sample included 252 745 women (median age at baseline, 57 years) with 38% self-reporting use of powder in the genital area. Ten percent reported long-term use, and 22% reported frequent use. During a median of 11.2 years of follow-up (3.8 million person-years at risk), 2168 women developed ovarian cancer (58 cases/100 000 person-years). Ovarian cancer incidence was 61 cases/100 000 person-years among ever users and 55 cases/100 000 person-years among never users (estimated risk difference at age 70 years, 0.09% [95% CI, -0.02% to 0.19%]; estimated HR, 1.08 [95% CI, 0.99 to 1.17]). The estimated HR for frequent vs never use was 1.09 (95% CI, 0.97 to 1.23) and for long-term vs never use, the HR was 1.01 (95% CI, 0.82 to 1.25). Subgroup analyses were conducted for 10 variables; the tests for heterogeneity were not statistically significant for any of these comparisons. While the estimated HR for the association between ever use of powder in the genital area and ovarian cancer risk among women with a patent reproductive tract was 1.13 (95% CI, 1.01 to 1.26), the P value for interaction comparing women with vs without patent reproductive tracts was .15.

Conclusions and relevance: In this analysis of pooled data from women in 4 US cohorts, there was not a statistically significant association between use of powder in the genital area and incident ovarian cancer. However, the study may have been underpowered to identify a small increase in risk.

Figure.. Subgroup Analyses for the Association Between Ever Use of Powder in the Genital Area and Risk of Ovarian Cancer, Pooled Hazard Ratios (HRs) and 95% CIs^a

^aAdjusted for study, race/ethnicity (white, African American, other), education (<high school, some college, ≥college graduate), body mass index (BMI [calculated as weight in kilograms divided by height in meters squared], restricted cubic spline), parity (0, 1, 2, ≥3 births), ever use of oral contraceptives, tubal ligation (yes or no), hysterectomy (yes or no), menopausal status (premenopausal or postmenopausal), ever hormone therapy use. When estimating HRs within a strata of a variable, that variable was not included in the adjustment set. ^bNumbers include only participants with complete covariate information. ^cEffect estimate based on menopausal status updated throughout follow-up. Of the 2168 cases, 165 were diagnosed while the participant was premenopausal and 2003 occurred after menopause. ^dAmong women who were postmenopausal at baseline. ^eCalculated as weight in kilograms divided by height in meters squared.