BACKGROUND AND PURPOSE:

• Evidence for a relationship between use of powder (usually talc and/or cornstarch) in the genital area and ovarian cancer has not been confirmed in cohort studies
• O’Brien et al. (JAMA, 2020) investigated the association between use of powder in the genital area and ovarian cancer using prospective observational data

METHODS:

• Data pooled from 4 large, US-based cohort studies
  • Nurses’ Health Study
    • Enrollment 1976 | Follow-up 1982 to 2016 | n = 81,869
  • Nurses’ Health Study II
    • Enrollment 1989 | Follow-up 2013 to 2017 | n = 61,261
  • Sister Study
    • Enrollment 2003 to 2009 | Follow-up 2003 to 2017 | n = 40,647
  • Women’s Health Initiative Observational Study
    • Enrollment 1993 to 1998 | Follow-up 1993 to 2017 | n = 73,267
• Exposures
  • Ever use of powder in the genital area
  • Long-term: ≥20 years use
  • Frequent: ≥1/week use
• Study design and data analysis
  • Covariate-adjusted hazard ratio (HRs) and 95% CIs were estimated using Cox proportional hazards models
  • To harmonize the 4 studies and account for different designs, estimated HRs were used | Calculations were based on an estimated risk that a woman will develop ovarian cancer by age 70 in both the exposed and unexposed groups
• Primary outcome
  • Incident ovarian cancer

RESULTS:

• Total of 252,745 women | Median age at baseline: 57 years
  • 38% self-reported use of powder in the genital area
  • Long-term use: 10%
  • Frequent use: 22%
• 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
  • Ever users: 61 cases/100,000 person-years 
  • Never users: 55 cases/100,000 person-years
  • 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)
  • Restricted to medically confirmed ovarian cancer cases, HR was lower | HR, 1.05 (95% CI, 0.96 to 1.16)
• The estimated HR vs to never use  
  • Frequent use 1.09 (95% CI, 0.97 to 1.23)
  • Long-term use 1.01 (95% CI, 0.82 to 1.25)
• No dose-response trends for duration and frequency of powder use were identified
• In medically confirmed cases HR was attenuated for ever use vs never use
  • HR 1.05 (95% CI, 0.96 to 1.16)
• When limited to women with a patent reproductive tract, an association was seen between powder ever use and ovarian cancer
  • Patent reproductive tract: HR 1.13 (95% CI, 1.01 to 1.26)
  • However, when comparing women with and without a patent reproductive tract, no differences were found between the group (P=0.15)

CONCLUSION:

• The use of powder in the genital area was not significantly associated with incident ovarian cancer
• However, the study may have been underpowered to detect a small increase in risk

Editorial (Gossett and Carmen; JAMA, 2020)

• Talc structurally similar and can be found in same mines as asbestos | Powders no longer contain asbestos | If there is an association, underlying mechanism may be related to inflammation
• Subgroup analysis of women with a patent reproductive tract did show a difference comparing ever to never users, but the effect size was below the threshold considered important by epidemiologists | The editorial authors caution that this result should not be selectively highlighted
• The editorial authors also state that the absence of a significant difference when comparing women with and without patent reproductive tracts

…confirms the overall conclusion that there is no demonstrable statistically significant association between use of powder in the genital area and ovarian cancer risk

Learn More – Primary Sources:

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

Editorial: Use of Powder in the Genital Area and Ovarian Cancer Risk

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