Perineal talc use and ovarian cancer risk: a case study of scientific standards in environmental epidemiology

Our plain-English summary of Perineal talc use and ovarian cancer risk: a case study of scientific standards in environmental epidemiology, by M. Huncharek, J. Muscat (European Journal of Cancer Prevention, 2011).

The study

• Authors: M. Huncharek, J. Muscat
• Journal: European Journal of Cancer Prevention
• Published: 2011;20(6):501-7
• Type of article: Review
• Cited by: 11 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

A number of observational studies (largely case-control) conducted over the last two decades suggest an association between use of talc powders on the female perineum and increased risk of ovarian cancer. A subset of these reports shows a roughly 30-60% increased risk of ovarian cancer associated with perineal talc exposure. A number of researchers partly base their conclusions of an association on the '…chemical relationship between talc and asbestos', the latter substance being a known human carcinogen. Although separating causal from noncausal explanations for an observed statistical association is a difficult process, there currently exist commonly accepted guidelines by which such inferences can be made. These scientific approaches include consideration of the strength of the association, the consistency of the finding across studies, and existence of a biological explanation of the observed phenomenon, among others. When applied to the context of a proposed talc/ovarian cancer association, we conclude that the weak statistical associations observed in a number of epidemiological studies do not support a causal association.

In plain English

This review article responded to a 2008 petition asking the US Food and Drug Administration to require ovarian cancer warnings on talc products. The authors applied the Hill criteria for judging cause and effect to published observational studies of talc powder used on the female perineum. Most of those studies reported odds ratios between 1.0 and 2.0. An earlier meta-analysis by Huncharek and colleagues of 15 case-control studies and one cohort study gave a summary relative risk of 1.33 (1.16 to 1.45). Within it, the figure was 1.19 (0.99 to 1.41) for hospital-based studies and 1.38 (1.25 to 1.52) for population-based ones. The one cohort study showed no association, and a number of studies suggested risk fell with more use. The authors wrote that some talc products contained small amounts of asbestos fibers before the early 1970s. They argued that asbestos causes cancer through its fiber structure, not its chemistry. They concluded that the weak associations are unlikely to be causal, while noting that a weak association does not rule out a causal connection.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Review article: a critique, using the Hill criteria for causal inference, of a 2008 Citizen's Petition to the US Food and Drug Administration seeking cancer warning labels on talc products. No new data were collected.
• Who was studied: No new participants. Published observational studies, largely case-control, of perineal talc use and ovarian cancer. Table 1 lists 16 studies (15 case-control and one cohort) published from 1989 to 2005.
• Exposure: Use of talc powders on the female perineum, by direct dusting or by dusting sanitary napkins. The article also discusses asbestos contamination of some talc products before the early 1970s, and the mineral differences between talc and asbestos (amphibole asbestos and serpentine asbestos, chrysotile).
• Main results:
  • Most of the reviewed observational studies reported odds ratios between 1.0 and 2.0, which the authors described as weak effects.
  • An earlier meta-analysis by Huncharek et al. (2003) pooled 15 case-control studies and one cohort study, giving a summary relative risk of 1.33 (1.16 to 1.45) for perineal talc use.
  • In that meta-analysis, hospital-based case-control studies gave 1.19 (0.99 to 1.41), described as no evidence of an effect. Studies with population-derived controls gave 1.38 (1.25 to 1.52). The authors took this difference as suggesting bias.
  • A pooled analysis of 20 studies by Langseth et al. (2008) gave a pooled odds ratio of 1.35 (1.26 to 1.46). Its heterogeneity test gave a P value of 0.036, which the authors said makes the pooled estimate invalid.
  • The only cohort study available when the petition was filed (Gertig et al., 2000) showed no association between perineal talc use and ovarian cancer risk. Table 1 lists its result as 1.05 (0.84 to 1.32).
  • The authors reported a lack of dose-response across studies, and wrote that a number of studies suggested risk decreases with increasing talc exposure.
  • The authors stated that before the early 1970s some talc products contained small amounts of asbestos fibers, and that the industries voluntarily eliminated this contamination after that time.
  • The authors argued that talc and asbestos are both magnesium silicates but are structurally distinct, and that fiber structure rather than chemical composition determines carcinogenicity.
  • Citing an earlier review by the same authors, the article stated that long-term clinical studies of talc applied to the human pleura (pleurodesis) had not shown a single case of cancer caused by the talc.
• The authors' conclusion: The authors concluded that, when accepted standards for causal inference are applied, the weak statistical associations cited in the petition do not support a causal link between perineal talc use and ovarian cancer.
• Limitations the authors state:
  • The authors acknowledged that a weak association does not rule out a causal connection.
  • The authors acknowledged that there are no firm data showing that cancer symptoms or treatment lead to increased short-term talc use, which is their proposed explanation for the inverse dose-response.
  • The authors noted that the Hill criteria do not fully solve the problem of causal inference in epidemiology.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Ovarian cancer, Talc and vermiculite.

Medical terms in this study, explained in our Lexicon: Talc, Ovarian Cancer, Epidemiology.

Related studies

• Perineal talc exposure and epithelial ovarian cancer risk in the Central Valley of California — P.K. Mills, D.G. Riordan, et al. (2004)
• Perineal use of talc and risk of ovarian cancer — H. Langseth, S.E. Hankinson, et al. (2008)
• A review of perineal talc exposure and risk of ovarian cancer — B.L. Harlow, P.A. Hartge (1995)
• Perineal talc use and ovarian cancer: a critical review — J.E. Muscat, M.S. Huncharek (2008)
• Talc, Asbestos, and Epidemiology: Corporate Influence and Scientific Incognizance — T.H. Tran, J.E. Steffen, et al. (2019)
• Serous Ovarian Cancer Caused by Exposure to Asbestos and Fibrous Talc in Cosmetic Talc Powders-A Case Series — J.E. Steffen, T. Tran, et al. (2020)

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