Dear Doctor: Some women, and juries, say that talc causes ovarian cancer, but doctors say it doesn't. Where's the evidence either way?
Dear Reader: Talc is a mineral composed of magnesium and silicate. Talcum powder, commonly known as baby powder, was first marketed by Johnson & Johnson in 1894. It was first used, and is still used, to prevent diaper rash. The concern regarding ovarian cancer is that talc may pass into a woman's uterus and then move up the fallopian tubes during menses. In fact, talc particles have been found in the fallopian tubes of women who have used talcum powder on sanitary napkins or pads.
The suggestion that talcum powder may lead to ovarian cancer first came from case-control studies. The largest of these was a combined analysis of eight different studies that compared 8,525 women (cases) who had ovarian cancers and 9,859 women (controls) who did not. In the studies, researchers asked women if they had used talcum powder in the genital area previously and how frequently. The authors concluded that the use of genital powder was associated with a 20 to 30 percent increase in some types of ovarian cancer.
One problem with that analysis is that some powders contain cornstarch, not talc. The other problem is that of recall bias. Women with ovarian cancer may report previous use of powders because they believe there may be a link between the powder and their ovarian cancer. Further, the authors did not find any dose response associated with powder use, meaning that they did not find a link between greater amounts of powder and ovarian cancer.
Other case-control studies have come up with similar conclusions. Based on such data, many lawsuits have contended a link between talcum powder and ovarian cancer. Two of these lawsuits have led to judgments of $72 million and $55 million against Johnson & Johnson.
One difficulty with analyzing statistical links to ovarian cancer is that the disease is somewhat rare; over her lifetime, the average woman has only about a 1 percent chance of developing it. To truly study a potential link between ovarian cancer and talcum powder, you would need large studies. You would also need prospective studies. A prospective study in this case would assess talcum powder use and follow women over time to see if they developed ovarian cancer.
Several studies have attempted to do this. The Nurses' Health Study included 78,683 women followed for nearly 13 years. These women were asked about their use of talcum powder and, over the course of 13 years, 307 cases of ovarian cancer were found. Note that researchers did not find talcum powder to be associated with ovarian cancer, although they did find a 9 percent increase among women who used talcum powder.
The Women's Health Initiative included 61,000 women followed for more than 12 years. In that study, researchers also found a minimal increase in ovarian cancer, but not a statistically significant one. The biggest problem with these prospective studies is that they need to be even larger and longer.
It's possible that there is a minimal increase in ovarian cancer among menstruating women who use talcum powder. However, this may have more historical relevance than topical relevance because fewer women are using talcum powder today than in years past. If you do use a genital powder, cornstarch powder would be a good alternative to talc.
, is an internist and assistant professor of medicine at the University of California, Los Angeles.
Ask the Doctors is a syndicated column first published by UExpress syndicate.
