Adult physical activity and XXXX risk.

@entity1 @entity249 @entity46
BACKGROUND: Regular exercise has been associated with a 40%-80% reduction in risk for @entity46 in several case-control studies. However, @entity1 experiencing symptoms prior to their diagnosis may be less likely to exercise than healthy controls, thus biasing the observed association. METHODS: Using data collected from the Nurses' Health Study II, a prospective cohort study of premenopausal US nurses that began in 1989, we have attempted to clarify this relation. Data are updated every 2 years with follow-up for these analyses through 2001. In 1989, 1991, and 1997 @entity1 reported average amount of time per week engaging in various physical activities. A metabolic equivalent (MET) score was assigned to each activity, and these were summed to estimate total activity. RESULTS: A total of 102,197 premenopausal @entity1 contributed 996,422 @entity1 -years of follow-up with 2703 cases of laparoscopically confirmed @entity46 . After adjusting for BMI at age 18, current BMI, smoking, parity, @entity249 status, oral contraceptive use, age at menarche, and menstrual cycle length and pattern in college, we observed only a slight reduction in the incidence of @entity46 , comparing the highest level of activity (>or=42 MET hours/week) to the lowest (<3 MET hours/week) (rate ratio = 0.89 [95% confidence interval = 0.77-1.03]). The association was limited to @entity1 with no past or concurrent @entity249 (P = 0.002, test for heterogeneity). No associations were seen with inactivity. CONCLUSIONS: In this first prospective assessment, we did not find evidence of the strong inverse association previously reported, although we cannot rule out a modest inverse association.
