Thune I, Lund E
Institute of Community Medicine, University of Tromsø, Norway.
Br J Cancer. 1996 May;73(9):1134-40. doi: 10.1038/bjc.1996.218.
We examined the association between self-reported occupational and recreational physical activity and the subsequent risk of colorectal cancer in a population-based cohort in Norway. During a mean follow-up time of 16.3 years for males and 15.5 years for females, 236 and 99 colon cancers and 170 and 58 rectal cancers were observed in males and females, respectively, among 53,242 males and 28,274 females who attended the screening between 1972 and 1978. Physical activity at a level equivalent to walking or bicycling for at least four hours a week during leisure-time was associated with decreased risk of colon cancer among females when compared with the sedentary group (RR = 0.62, 95% CI 0.40-0.97). Reduced risk of colon cancer was particularly marked in the proximal colon (RR = 0.51, 95% CI 0.28-0.93). This effect was not observed for occupational physical activity alone, probably due to a narrow range of self-reported physical activity at work among females. However, by combining occupational and recreational physical activity we observed an inverse dose-response effect as increasing total activity significantly reduced colon cancer risk (P for trend = 0.04). Among males 45 years or older at entry to the study, an inverse dose-response effect was observed between total physical activity and colon cancer risk (P for trend = 0.04). We also found in males a stronger preventive effect for physical activity in the proximal as compared to distal colon. In addition, we found a borderline significant decrease in colon cancer risk for occupational physical activity in males 45 years or older when compared to the sedentary group (RR = 0.74, 95% CI 0.53-1.04). All results were adjusted for age, body mass index, serum cholesterol and geographic region. No association between physical activity and rectal cancer was observed in males or females. The protective effect of physical activity on colon cancer risk is discussed in regard to energy balance, dietary factors, age, social class, body mass index and gastrointestinal transit time.
我们在挪威一个基于人群的队列中，研究了自我报告的职业和休闲体力活动与随后患结直肠癌风险之间的关联。在男性平均随访16.3年、女性平均随访15.5年期间，在1972年至1978年参加筛查的53242名男性和28274名女性中，分别观察到236例和99例结肠癌以及170例和58例直肠癌。与久坐组相比，女性在休闲时间进行相当于每周步行或骑自行车至少四小时的体力活动与患结肠癌风险降低相关（风险比=0.62，95%置信区间0.40-0.97）。结肠癌风险降低在近端结肠尤为明显（风险比=0.51，95%置信区间0.28-0.93）。单独的职业体力活动未观察到这种效应，可能是由于女性自我报告的工作体力活动范围较窄。然而，通过结合职业和休闲体力活动，我们观察到一种反向剂量反应效应，即总活动量增加显著降低结肠癌风险（趋势P值=0.04）。在研究开始时年龄在45岁及以上的男性中，观察到总体力活动与结肠癌风险之间存在反向剂量反应效应（趋势P值=0.04）。我们还发现，与远端结肠相比，男性体力活动对近端结肠的预防作用更强。此外，与久坐组相比，45岁及以上男性的职业体力活动使结肠癌风险有边缘性显著降低（风险比=0.74，95%置信区间0.53-1.04）。所有结果均根据年龄、体重指数、血清胆固醇和地理区域进行了调整。在男性或女性中均未观察到体力活动与直肠癌之间存在关联。从能量平衡、饮食因素、年龄、社会阶层、体重指数和胃肠道转运时间等方面讨论了体力活动对结肠癌风险的保护作用。
