Study Links Obesity To Ovarian Cancer In Older Women Who Have Not Used HRT

Main Category: Obesity / Weight Loss / Fitness
Also Included In: Seniors / Aging;  Women's Health / Gynecology;  Ovarian Cancer
Article Date: 14 Jan 2009 - 4:00 PDT

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Obese older women who have never used hormone replacement therapy have nearly twice the risk of their normal weight peers of developing ovarian cancer, according to a study by the researchers at the National Cancer Institute, the New York Times reports. When assessing ovarian cancer across all older women, researchers found that obese women faced only a slightly higher risk for ovarian cancer than those of normal weight.

The study -- which will appear in the Feb. 15 issue of Cancer -- examined data on 94,525 women ages 50 to 71. After seven years, 303 of the women developed ovarian cancer. Women who were obese -- defined as having a body mass index of 30 or more -- were 1.26 times more likely to develop the cancer than women with a BMI of less than 25, which is considered normal weight. This difference was not statistically significant. However, among a subgroup of women who had not taken HRT, obese women were 1.83 times more likely than women of normal weight to develop ovarian cancer. The study found no association between BMI and ovarian cancer among women who had taken hormones or among women with a family history of the disease.

Because HRT might play a role in the development of cancer, comparing cancer rates among women who have never used hormones helps tease out the effects of other risk factors, the study's authors said. Michael Leitzmann, a former investigator at the NCI and an author of the study, said, "We speculate that what may be driving the increased risk among the obese is the surplus estrogen produced by fat cells in the body." Previous studies on the association between obesity and ovarian cancer have been inconsistent and contradictory, and experts believe the new findings will not be the last word on the matter, the Times reports. A 2007 review of earlier clinical trials found that being overweight or obese was associated with a higher risk for ovarian cancer, but a 2008 pooled analysis found that BMI was linked to the disease only in premenopausal women, who have a very low risk to begin with.

Leo Schouten, an author of the pooled analysis, said, "This needs to be replicated in other populations (with lower proportions of postmenopausal hormone users) before we can decide whether this is a real and not a chance finding." James Lacey -- an author of the new study -- said that previous analyses of studies examining the link between obesity and ovarian cancer included older data and that different risks may be emerging now that more U.S. residents are obese. "It's another piece to the puzzle," he said (Rabin, New York Times, 1/7).

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