Physical activity and risk of colorectal cancer in Japanese men and women: the Japan Public Health Center-based prospective Study
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To prospectively examine the association between physical activity and the risk of developing colorectal cancer in a large population-based cohort study of Japanese men and women, and to investigate whether the effects of physical activity on colorectal cancer risk differ by sex and subsite.
We analyzed data from a population-based cohort of 65,022 subjects. A total of 486 incident colorectal cancers (154 proximal colon, 166 distal colon and 149 rectal cancers) was identified during 6 years of follow-up.
We observed a significant inverse association between physical activity and the risk of developing colorectal cancer, particularly colon cancer, among men. Relative to men in the lowest level of metabolic equivalent (MET) hours per day, those in the highest level had a RR of 0.69 (95% CI = 0.49–0.97). A significant decrease in risk of colorectal cancer was associated with increasing MET hours per day among men. This inverse association was essentially limited to colon cancer. A significant decrease in risk with increasing MET-hour score was observed predominantly for proximal colon cancer among men. In contrast, no significant decrease was seen among women.
These findings suggest that physical activity may prevent colon cancer among Japanese men.
KeywordsColorectal cancer Physical activity Prospective study Japan
K-J.L. was awarded a Visiting Scientist Fellowship from the Foundation for Promotion of Cancer Research in Japan. The authors thank all staff members in each study area for their unfailing efforts in conduction the baseline and follow-up surveys. We also express our gratitude to the Iwate, Aomori, and Okinawa Cancer Registries for providing the incidence data. This work was supported by a Grant-in-Aid for Cancer Research and by the Third-Term Comprehensive Control Research for Cancer from the Ministry of Health, Labour and Welfare, Japan.
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