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Talc Classified as "Possible Human Carcinogen"

October 10, 2008 — Regular use of talc in the genital area was significantly associated with an increased risk for ovarian cancer. The researchers say that genital use of talc should be avoided.

This is not a new finding — the association between genital talc use and an increased risk for ovarian cancer has been reported previously, and was confirmed in a meta-analysis of 16 studies.

These latest results "provide additional support for a main effect of genital talc exposure on epithelial ovarian cancer," say the researchers. Also, the finding of highly significant trends between increasing frequency of use and risk "strengthens the evidence of an association, because most previous studies have not observed a dose response," they point out.

In addition, this study was the first to analyze different genotypes. Researchers found that genes in detoxification pathways might be involved in the biologic response to talc. The association between talc and ovarian cancer might vary by genotype, the researchers report, although they add that more research is needed to confirm these findings.

"We believe that women should be advised not to use talcum powder in the genital area, based on our results and previous evidence supporting an association between genital talc use and ovarian cancer risk," commented author Margaret Gates, ScD, research fellow at Brigham and Women's Hospital, in Boston, Massachusetts. "Physicians should ask the patient about talc use history and should advise the patient to discontinue using talc in the genital area if the patient has not already stopped."

"An alternative to talc is cornstarch powder, which has not been shown to increase ovarian cancer risk, or to forgo genital powder use altogether.

No Risk From Talc Use Elsewhere on the Body

The latest findings come from an analysis of data from 2 separate study populations. Researchers obtained records for 1231 epithelial ovarian cancer cases and 1244 controls from the New England Case Control (NECC) Study, and on 210 cases and 600 controls from the prospective Nurses' Health Study (NHS). In the questionnaire about talc use, "regular" use was defined as the application of powder to the genital/perineal region at least once a week.

Talc use elsewhere on the body was not associated with an increase in ovarian cancer risk, the researchers point out.

"It is unclear whether talc applied to the perineum can reach the ovaries, although some studies have shown that inert particles can travel through the female genital tract to the fallopian tubes and ovaries, and others have found talc particles in ovarian tissue," the researchers write. They also note that some studies have shown that talc particles can induce an inflammatory response in vivo, whereas others have suggested an immune-mediated mechanism. It might be that exposure of the lower genital tract to talc is sufficient to cause changes, such as production of heat shock proteins, accumulation of talc in pelvic lymph nodes, or decreased levels of anti-MUCI antibodies, and these could lead to an increase in the risk for ovarian cancer. The association between genital talc use and increased risk for ovarian cancer is not new, has classified talc as a "possible human carcinogen."

However, there have been some questions about this association, including the lack of a dose-response relationship, whether talc particles could actually reach the ovaries, and whether it is the contaminants in talc (asbestos and quartz) that are to blame, rather than the talc itself, Dr. Thun commented. The first question has been answered by this latest study, and evidence is growing for the second, but the question about contaminants remains, and it is unclear whether modern products free of these contaminants carry a similar risk.

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