Physical activity, water intake and risk of colorectal cancer in Taiwan: A hospital-based case-control study

The age‐adjusted mortality rates of colorectal cancer have been rising in Taiwan over the past 2 decades, and colorectal cancer is now the third leading cause of cancer mortality in the country. We conducted a hospital‐based case‐control study to clarify the nature of the association between physical activity, water intake and colorectal‐cancer risk in Taiwan. A total of 163 subjects (aged 33–80 years) with histologically confirmed primary colorectal cancer and 163 hospital controls were enrolled during 1992. Dietary intake, physical activity and other lifestyle activities were assessed using a comprehensive food‐frequency and lifestyle‐activity questionnaire. Adjusted odds ratios (OR) and 95% confidence intervals (CI) were estimated using conditional logistic‐regression analysis. A strong inverse dose‐response relation between increased water intake and rectal cancer was found among men after adjustment for other risk factors (p for trend = 0.0005). The OR for rectal cancer among men in the highest tertile of water intake was 0.08 (95% CI, 0.02–0.35) compared with that among men in the lowest tertile (OR = 1). Similar but not significant trends were seen among women (p = 0.29). The OR for colon cancer among men with active leisure‐time physical activity was 0.19 (95% CI, 0.05–0.77) times that among sedentary men (p for trend = 0.03). However, physical activity was not associated with colon‐cancer risk among women (p = 0.48). No differences in the amount of water intake were found related to level of physical activity. These findings add to the evidence that leisure‐time activity may reduce colon‐cancer risk, not only in high‐risk but also in low‐risk populations, and support the potential beneficial effect of increased water intake in reducing colorectal‐cancer risk. Int. J. Cancer 82:484–489, 1999. Copyright © 1999 Wiley‐Liss, Inc.