Background: Physical activity and sedentary behavior may influence ovarian cancer risk, but clear evidence is lacking.
Methods: We prospectively investigated the relations of self-reported physical activity and sedentary behavior to ovarian cancer incidence in a cohort of 148,892 U.S. women ages 50-71 years at baseline (1995-1996), who were followed through 2006. Multivariate Cox proportional hazard models were used to estimate relative risks (RR) and 95% confidence intervals (CI). We also conducted analysis by hormone use, body mass index (BMI), and cancer subtype.
Results: We identified 753 incident epithelial ovarian cancers. Overall, neither physical activity nor sedentary behavior at baseline was associated with ovarian cancer risk. Compared with women who never or rarely engaged in vigorous physical activity in the past year, women who reported more than 5 times/week of vigorous physical activity had an RR of 1.05 (95% CI, 0.84-1.32). Women who sat 7+ hours/day had an RR of 1.05 (95% CI, 0.80-1.37) compared with those reporting <3 hours of sitting. The associations were not modified by hormone use or BMI and were similar for both serous and non-serous subtypes.
Conclusions: Physical activity and sedentary behavior in middle and older ages were not associated with ovarian cancer risk.
Impact: We found no clear support for a role of physical activity and sedentary behavior in ovarian cancer risk.