Background: There is a strong evidence for a protective role of physical activity (PA) on cancers of the colon, breast (postmenopausal) and endometrium, but data are less consistent or scarce for other cancer types. This study assessed the relationship between occupational and recreational PA and cancer risk among men in a population-based case-control study conducted in Montreal, Canada.
Methods: Incident cases of cancer of the lung (n=857), colon (n=496), bladder (n=484), prostate (n=449), stomach (n=251), rectum (n=248), non-Hodgkin's lymphoma (n=215), kidney (n=177), pancreas (n=116), melanoma (n=103), esophagus (n=99), Hodgkin's lymphoma (n=54), and 533 population controls, were interviewed. Detailed lifetime occupational PAs were translated into metabolic equivalents. Participation in sports and outdoor activities was elicited.
Results: Compared to those with low lifetime occupational PA levels, men with high occupational PA levels had decreased odds ratios (OR) for all cancer types. The strongest evidence was for cancers of the colon [OR: 0.58, 95% confidence interval (CI): 0.34-0.99] and the prostate (OR: 0.54, 95% CI: 0.31-0.95). Men engaging in sports and outdoor activities had lower risks of lung (OR: 0.69, 95% CI: 0.52-0.91), esophageal (OR: 0.54, 95% CI: 0.30-0.97) and bladder (OR: 0.78, 95% CI: 0.59-1.05) cancers, and somewhat increased risks of melanoma (OR: 1.24, 95% CI: 0.73-2.12).
Conclusions: A protective effect of high lifetime occupational PA levels was observed for colon and prostate cancers. A tendency for inverse associations was also noted for several other cancer types. Recreational PA was inversely related with smoking-related cancers including lung, esophageal and bladder cancers.
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