A large pooled analysis has found no significant link between the use of talc-based powders in the genital area and the risk for ovarian cancer. With data from more than 252,000 women, the estimated risk for ovarian cancer by 70 years of age in ever users of talc and similar powders in the genital area was not significantly different from the risk in women who were never exposed, with a hazard ratio (HR) of 1.08 (95% confidence interval [CI], 0.99-1.17).
As reported in JAMA,1 a similar nonsignificant difference was observed when the duration and frequency of powder use in the genital area was examined, with no evidence of a significant dose-response relationship identified.
The analysis counters findings from case-control studies, specifically a 2018 meta-analysis of 24 case-control studies and 3 cohort studies that showed a positive association between any use of perineal talc and risk for developing epithelial ovarian cancer in the case-control studies with no association found in the cohort studies. However, cohort studies found an association between talc use and invasive serous-type ovarian cancer (odds ratio, 1.25; 95% CI, 1.01-1.55).2
Katie M. O’Brien, PhD, Staff Scientist, Epidemiology Branch, Chronic Disease Epidemiology Group, National Institute of Environmental Health Sciences, Research Triangle Park, NC, and colleagues pooled data from 4 large prospective cohort studies of 252,745 women with a median age at baseline of 57 years. Of these women, slightly more than one-third (39%) reported using powder in the genital area, 10% reported long-term use (defined as ≥20 years), and 22% reported frequent use (defined as ≥1 time weekly). After a median follow-up of 11.2 years, 2168 women developed ovarian cancer.1
There were 61 incident cases of ovarian cancer per 100,000 person-years among ever users of powder versus 55 cases per 100,000 person-years among never users, for an estimated risk difference at age 70 years of 0.09%.
The covariate-adjusted risk difference for long-term use versus never use was 0.01%, corresponding to an HR of 1.01 (95% CI, 0.82-1.25; P = .57). There was no dose-response relationship; the covariate-adjusted risk difference for frequent use versus no use was 0.10%, translating to an HR of 1.09 (95% CI, 0.97-1.23; dose-response P = .20).
When restricted to women with patent reproductive tracts (ie, women who had not had their wombs removed in a hysterectomy, or had their fallopian tubes tied for the purposes of sterilization), the HR was 1.13 (95% CI, 1.01-1.26) and the estimated covariate-adjusted risk difference was 0.15%. In other words, the risk difference between those who used powder and those who did not was statistically significant, albeit by a small margin. Among women without patent reproductive tracts, the results were nonsignificant, with an estimated HR of 0.99 (95% CI, 0.86-1.15).1 Most importantly, however, there was no significant difference in the HRs in the patent and nonpatent subgroups, confirming the overall conclusion that there is no demonstrable statistically significant association between use of powder in the genital area and ovarian cancer risk.
“Although the study was underpowered to detect small changes in risk, this is, to our knowledge, the largest study of this topic to date, and it is believed that no other large prospective cohorts have collected data on powder exposure in the genital area,” the investigators wrote.
In an editorial that accompanied the study, Dana R. Gossett, MD, MSCI, Professor, Obstetrics, Gynecology, and Reproductive Sciences, University of California, San Francisco, and Marcela G. del Carmen, MD, MPH, Professor, Obstetrics, Gynecology, and Reproductive Biology, Harvard University Medical School, Boston, MA, wrote, “The study by O’Brien et al represents the largest cohort to date to examine whether an association exists between powder use in the genital area and ovarian cancer risk, and the findings are overall reassuring….The rigorously conducted study…contributes important and timely data about the potential link between use of powder in the genital area and risk of ovarian cancer.”3
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