A new study published in the Journal of the American Medical Association (JAMA), which found “no statistically significant association” between genital talc use and ovarian cancer, could aid Johnson & Johnson in dealing with its nearly 17,000 pending lawsuits charging that its popular talc-based baby power caused their cancer.

At the same time, although this is reportedly the biggest study to date, it might not be a major boon, as the methodology used was not always uniform, and the powders tested (not all from J&J) did not all have the same makeup.

There were other flaws in the research, including the small sample of who had ovarian cancer at all among the women whose data was studied. Also, not all of the powders contained talc – some contained cornstarch – and it was unclear if any were found to be laced with asbestos, as has been claimed in some of the J&J lawsuits.

Further criticism focused on the fact that the study participants included mostly white, well-educated women, half of whom had a Body Mass Index (BMI)  less than 25, so that is not clear if this result can be generalized to other demographics.

The research focused on pooled data from 252,745 women in the United States with a median age of 57 years. Among these, 38% said they used powder in their genital area, 10% said they had been doing so for at least 20 years and 22% reported using it at least once a week.

In a follow-up after about 11 years, 2,168 of the women had developed ovarian cancer. Comparing the case numbers, the study’s authors said they found an 8% increased risk of ovarian cancer for women who reported ever using talc in the genital area. For powder users with an intact reproductive system, the increase in risk rose to 13% compared with those who never used powders.

One comment on the conclusions noted that if future research shows a possible association between powder and ovarian cancer among women who had no history of hysterectomy or tubal ligation, there could be some truth to the hypothesis that the powder may be irritating or inflaming the reproductive tract as there is some correlation between pelvic inflammatory disease and ovarian cancer.

Studies conducted in the past have shown mixed results. In 2006, the International Agency for Research in Cancer (IARC) of the World Health Organization (WHO) classified the use of talc in the genital area as "possibly carcinogenic to humans." This is the same agency that classified the key agrochemical ingredient glyphosate as a possible human carcinogen. However, pharma journals noted that this is considered its weakest classification as a cancer cause.

For the American Cancer Society, talc's relation to cancer "is less clear. While saying “ there is some suggestion of a possible increase in ovarian cancer risk," ACS said its bottom-line advice is, "until more information is available, people concerned about using talcum powder may want to avoid or limit their use of consumer products that contain it."

A J&J spokesperson told the journal Fierce Pharma that the study "drew from data already gathered on tens of thousands of women followed over many years and reaches a conclusion that is consistent with the more than 40 years of independent research and clinical evidence that supports the safety of talc."