Abstract B70: Physical activity and BMI in a population-based case-control study of endometrial cancer risk

Abstract

Abstract Introduction: Endometrial (uterine corpus) cancer is the fourth most common incident cancer among women in the United States. Recent systematic reviews have published summary data suggesting an inverse association between physical activity and risk of endometrial cancer. However, studies show conflicting results, many do not report on reliability or validity of physical activity questionnaires, and few studies have examined the combination of physical activity and BMI on endometrial cancer risk. Thus, we evaluated the independent association between physical activity, BMI and endometrial cancer risk, as well as the combination of physical activity and BMI on risk. Methods: We identified 668 incident cases of endometrial cancer through the population-based Rapid Case Ascertainment Shared Resource at the Yale Cancer Center and age-matched 665 controls using random digit dialing. Research staff interview-administered structured questionnaires, collecting information on demographic features, environmental exposures and lifestyle factors. We performed unconditional logistic regression to examine the relationship between moderate- to vigorous-intensity sports/recreational physical activity (MV PA) and endometrial cancer risk. Results: We found, compared to women reporting 0 Metabolic Equivalent (MET) hours per week of MV PA, those who reported 7.5 MET hr/wk or more of MV PA had a 34% lower endometrial cancer risk (Odds Ratio (OR) = 0.66, 95% CI: 0.50-0.87) after adjusting for other risk factors including BMI. We created a composite measure of physical activity (inactive ≤ 7.5 MET hr/wk, active > 7.5 MET hr/wk) and BMI (normal weight < 25 kg/m,2 overweight ≥ 25 kg/m2), and found that women who were normal weight and active had a 73% lower endometrial cancer risk (OR = 0.27, 95% CI: 0.19-0.38) compared to the reference group of overweight and inactive. Women who were normal weight but inactive had a 55% lower endometrial cancer risk (OR = 0.45, 95% CI: 0.31-0.65) and women who were overweight but active had a 38% lower risk of endometrial cancer (OR= 0.62, 95% CI: 0.47-0.83). Conclusion: Our data support an inverse, independent association between physical activity and endometrial cancer risk after adjusting for BMI and other risk factors. However, the combination of physical activity and BMI appears to further impact risk of endometrial cancer. Programs to increase physical activity levels to the current recommendation of 150 minutes per week may lower the incidence of endometrial cancer. Citation Information: Cancer Prev Res 2010;3(12 Suppl):B70.