Association between frequency and intensity of recreational physical activity and epithelial ovarian cancer risk by age period.

The objective of this study was to examine the association between recreational physical activity across the life span and epithelial ovarian cancer. This relationship was investigated using data from the Ontario arm of the National Enhanced Cancer Surveillance Study, a Canadian population-based case-control study. Data were collected from 240 epithelial ovarian cases and 891 female controls using a self-administered questionnaire. The frequency and intensity of recreational activity in four age periods (mid-teens, early 30s, early 50s, 2 years ago) were examined. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using multivariate logistic regression. Participation up to two times/week, but not more than two times/week, in strenuous recreational activity in mid-teens (OR = 1.69, 95% CI=1.15-2.49) and early 30s (OR = 1.45, 95% CI=1.03-2.05) was associated with increased risk of ovarian cancer. For activity 2 years ago, participation in both strenuous activity (OR = 0.69, 95% CI=0.47-1.01) and moderate activity (OR = 0.55, 95% CI=0.34-0.88) up to two times/week was associated with reduced ovarian cancer risk. Participating more than two times/week was not associated with ovarian cancer risk. Strenuous activity performed in early 50s and moderate activity performed in mid-teens, early 30s, and early 50s were unrelated to risk. In conclusion, strenuous recreational activity early in life may increase the risk of ovarian cancer, whereas more recent recreational activity may reduce the risk.