INTRODUCTION:

Published studies of physical activity, BMI, and endometrial cancer risk show conflicting results and many do not report on reliability or validity of physical activity questionnaires.

METHODS:

We collected physical activity data on 667 incident cases of endometrial cancer and 662 age-matched controls. Interview-administered questionnaires, collecting demographic and lifestyle information, including a validated questionnaire for physical activity. We performed unconditional logistic regression to examine the relationship between moderate- to vigorous-intensity sports/recreational physical activity (MV PA), sit time, and endometrial cancer risk.

RESULTS:

Compared to women reporting 0 metabolic equivalent (MET) hours per week of MV PA, those who reported 7.5 MET h/wk or more had a 34% lower endometrial cancer risk (odds ratio (OR) = 0.66, 95% CI 0.50-0.87) after adjusting for risk factors including BMI. Those women sitting more than 8 h per day had a 52% increased odds (95% CI 1.07-2.16) of endometrial cancer compared to those sitting less than 4 h per day. We created a composite measure of physical activity and BMI and found that women with a BMI <25 and activity levels ≥7.5 MET h/wk had a 73% lower endometrial cancer risk (OR = 0.27, 95% CI 0.18-0.39) compared with the reference group of overweight (BMI ≥25) and sedentary (MET h/wk = 0).

CONCLUSION:

Our data support an inverse, independent association between physical activity and endometrial cancer risk after adjusting for BMI and other risk factors.