title: Physical activity and risk of colorectal cancer in Japanese men and women: the Japan Public Health Center-based prospective study.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  These findings suggest that physical activity may prevent colon cancer among Japanese men.
authors.affiliation: Epidemiology and Prevention Division, Research Center for Cancer Prevention and Screening, National Cancer Center, 5-1-1 Tsukiji, Tokyo, Japan.
authors.forename: Kyung-Jae
authors.initials: KJ
authors.lastname: Lee
authors.forename: Manami
authors.initials: M
authors.lastname: Inoue
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Otani
authors.forename: Motoki
authors.initials: M
authors.lastname: Iwasaki
authors.forename: Shizuka
authors.initials: S
authors.lastname: Sasazuki
authors.forename: Shoichiro
authors.initials: S
authors.lastname: Tsugane
mesh_terms: D000328:Adult; D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000453:epidemiology*; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012306:Risk; D012737:Sex Factors