Ovarian Cancer Risk Influenced by Diet?
Abstract & Commentary
By Robert L. Coleman, MD, Associate Professor, University of Texas; M.D. Anderson Cancer Center, Houston, is Associate Editor for OB/GYN Clinical Alert.
Dr. Coleman reports no financial relationship to this field of study.
Synopsis: Low fat diet modification, an intervention study of the WHI demonstrates a reduction in ovarian cancer risk
Source: Prentice RL, et al. J Natl Cancer Inst. 2007; 99:1534-1543.
The Women's Health Initiative (WHI) is a randomized controlled trial which is evaluating cancer and disease risk among healthy menopausal women aged 50-79 years. One study outcome was to evaluate the impact a low-fat diet could have on the cumulative risk of invasive cancer of the colon and breast. In addition, invasive cancer of the ovary and endometrium were listed as potential sites of benefit from dietary modification (DM). Over the 6 years of enrollment, 48835 women were randomly assigned to DM (n=19541) or comparison (usual diet, n= 29294) and followed a mean of 8.1 years. The DM goal was to reduce total fat intake to 20% of energy and increase consumption of vegetables, fruits and grains. Cancer outcomes were evaluated as individual site (ovarian and endometrium) as well as total invasive cancer and invasive cancers at other sites between the randomization arms. Overall, ovarian cancer risk was significantly reduced in the intervention group compared to usual diet. The risk reduction (40%) became significant after 4 years suggesting an important trend from intervention. No difference in endometrial or total cancer risk as observed in the DM group compared to controls. Diet modification led to reductions in weight although this was not a primary objective of the plan and did not impact endometrial cancer risk. The author's conclude that the a low-fat diet pattern may impact the incidence of ovarian cancer in menopausal women.
Commentary
Primary objectives of the DM intervention study were assess to breast and colon cancer risk in menopausal women. These data were previously reported with a 9% reduction in the hazard for breast cancer (95% CI 0.83- 1.01) with the highest reduction seen in those women with the highest baseline fat energy index. No association was seen for colorectal cancer risk. Previous epidemiological studies have suggested that ovarian cancer risk might be arbitrated by dietary fat modification but the results were far from consistent. However, the association of obesity and endometrial cancer has been well-documented. The current study's findings suggest that while obesity may be a risk for endometrial cancer, dietary fat calorie consumption may not necessarily modify this risk. However, an interesting trend was observed in regard to ovarian cancer. And, the observation that risk was a function of time, being significant after 4 years of modification, helps to support the "may impact" statement in the author's conclusions. However, the data are underwhelming given the large sample and the concerns for unlikely significance if adjustment of the p-values are made for the multiple comparisons. Even if a modest adjustment were made the HRs would cross unity. In addition, while compliance with the program was attempted by frequent group counseling sessions (18 year 1 and quarterly thereafter), compliance is very difficult to validate with very modest reductions in fat energy reductions. Nevertheless, the observations are of interest and further investigation may lead to important epigenetic phenomena that raise or lower incident ovarian cancer risk.
The Women's Health Initiative (WHI) is a randomized controlled trial which is evaluating cancer and disease risk among healthy menopausal women aged 50-79 years.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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