A recent study published in JAMA has revealed that women who use powder in the genital area do not face a significantly higher risk of ovarian cancer, challenging previous findings that suggested a potential link between the two.
While the study did not identify a substantial increase in ovarian cancer risk associated with genital powder use, the researchers acknowledged that their investigation may have lacked the power to detect a minor elevation in risk.
Previous case-control studies had indicated positive associations between the use of genital powder and ovarian cancer, with estimated odds ratios of 1.24 (pooled analysis) and 1.31 (meta-analysis). However, these findings were susceptible to recall bias, potentially exacerbated by recent talc-related lawsuits and heightened media coverage. Thus, researchers emphasized the importance of evaluating the talc-ovarian cancer association using prospective data.
Cohort studies conducted previously yielded mixed results regarding the potential link between powder use and ovarian cancer.
To address these inconsistencies, Katie M. O’Brien, PhD, from the National Institute of Environmental Health Sciences, and her colleagues conducted a pooled analysis involving 252,745 women from four large cohorts: the Nurses’ Health Study, the Nurses’ Health Study II, the Sister Study, and the Women’s Health Initiative Observational Study. Of these participants, 38% reported ever using genital powder, 22% used it at least once a week, and 10% reported long-term use for 20 years or more.
Over a median follow-up period of 11.2 years, the incidence of ovarian cancer was 61 cases per 100,000 person-years among women who had ever used genital powder and 55 cases per 100,000 person-years among those who had never used it (estimated hazard ratio [HR] = 1.08; 95% confidence interval [CI], 0.99-1.17). For women who used genital powder at least once a week compared to those who never used it, the estimated HR was 1.09 (95% CI, 0.97-1.23). For those who used powder for 20 years or more, the HR was 1.01 (95% CI, 0.82-1.25).
Importantly, the study did not find significant evidence of heterogeneity across the cohorts. However, researchers hypothesized that women with patent reproductive tracts might be more susceptible to the potential effects of powder on ovarian cancer. Among this subgroup, there was a “possible positive association” between genital powder use and ovarian cancer (estimated HR = 1.13; 95% CI, 1.01-1.26). Yet, this association did not significantly differ from the one observed among women with non-patent reproductive tracts, leading the researchers to consider this finding exploratory and hypothesis-generating.
“The main analysis included 2,168 ovarian cancer cases that developed over 3.8 million person-years. This far exceeds a previous meta-analysis of [previously] published … results (890 cases over 182,000 person-years),” the researchers noted. Nonetheless, they highlighted that the study’s power to investigate links to peritoneal or fallopian tube cancers, or other histotypes apart from serous, remained limited. Improvements in tumor type classification may provide further insights, especially for fallopian tube cancers, which could potentially be the primary point of origin for most serous ovarian cancers.
In a related editorial, Dana R. Gossett, MD, MSCI, from the University of California, San Francisco, and Marcela G. del Carmen, MD, MPH, from Harvard University Medical School, described the findings by O’Brien and colleagues as “reassuring” for women who use or have used genital powder. They also suggested that future research in this area should focus on women with intact reproductive tracts, with particular attention to the timing and duration of genital powder exposure. However, they acknowledged that accumulating such data may take many years, given the low rates of current genital powder use among women in the United States.
In conclusion, the study by O’Brien and colleagues contributes valuable and timely data regarding the potential connection between genital powder use and the risk of ovarian cancer, according to Gossett and del Carmen.
[Disclosure: Dana R. Gossett reports a relationship with Bayer for expert consultancy services for the Mirena intrauterine device outside the submitted work. Please see the study and editorial for all other authors’ relevant financial disclosures.]
