Higher BMI Tied to Ovarian Cancer Risk

A woman's height and body mass index (BMI) may significantly influence her ovarian cancer risk, a large meta-analysis found.

For each 5-cm increase in height, the adjusted relative risk for ovarian cancer was 1.07 (95% CI 1.05 to 1.09, P<0.001), reported the Collaborative Group on Epidemiological Studies of Ovarian Cancer.

And among women who never used hormone replacement therapy for menopause, the relative risk for each 5 kg/m² increase in BMI was 1.10 (95% CI 1.07 to 1.13, P<0.001), the group reported online in PLoS Medicine.

Each recent decade in developed countries has seen an increase in height of approximately 1 cm and a rise in BMI of 1 kg/m² among women not using hormone replacement therapy, according to the researchers.

"As an illustration of the public health consequences of such changes in height and weight, these findings suggest an associated increase in ovarian cancer incidence of 3% per decade if all other factors relevant for ovarian cancer remained constant," they wrote.

Although approximately 50 studies have collected data on anthropometric measures and ovarian cancer risk, the results of only about half have been published and the findings have been inconclusive.

Link Between Ovarian Cancer, BMI May Vary by Hormone Therapy Use There is a "modest positive relation" between body mass index (BMI) and risk for ovarian cancer, but the risk is considerably elevated in women who have never used menopausal hormone therapy (MHT; also known as hormone replacement therapy), according to a prospective study of 94,000 mostly postmenopausal women published online January 6 in Cancer. In the study, the risk for ovarian cancer increased by 80% in obese women, compared with normal-weight women, among those who never used MHT.

"Further studies are needed to test the hypothesis that the relation between BMI and ovarian cancer varies according to menopausal hormone therapy," write the authors, led by Michael F. Leitzmann, MD, PhD, from the Institute of Epidemiology and Preventive Medicine at the University of Regensburg, in Germany. Dr. Leitzmann was formerly at the National Cancer Institute in the United States, where the study was undertaken.

In discussing the background of the study, Dr. Leitzmann and colleagues note that "convincing epidemiologic evidence links excess body mass to increased risks of endometrial and postmenopausal breast cancers, but the relation between . . . BMI and ovarian cancer risk remains inconclusive."

The new study adds to the literature on ovarian cancer, BMI, and MHT, which is "sparse," say the authors. They also suspect that any ovarian cancer risk that is associated with obesity is likely related to a "hormonal mechanism."

To more-fully examine these concerns, the collaborative group collected and reanalyzed all the available evidence from 47 published and unpublished studies that included 25,157 women with ovarian cancer and 81,311 controls.