Martínez M E, Giovannucci E, Spiegelman D, Hunter D J, Willett W C, Colditz G A
Department of Nutrition, Harvard School of Public Health, Boston, MA, USA.
J Natl Cancer Inst. 1997 Jul 2;89(13):948-55. doi: 10.1093/jnci/89.13.948.
Physical inactivity and high body mass index (weight in kilograms divided by height in square meters) have been linked to increased risk of colon cancer. However, none of the few prospective studies in women has shown a statistically significant reduction in colon cancer incidence or mortality associated with increased leisure-time physical activity.
In this prospective study, we asked whether leisure-time physical activity, body mass index, or body fat distribution could significantly influence the risk of colon cancer in women.
The participants in this study were enrolled in the Nurses' Health Study, which began in 1976. Every 2 years, the women provided additional personal information and information on medical risk factors and major medical events. The time spent per week at a variety of leisure-time physical activities was determined, and the time spent at each activity was multiplied by its typical energy expenditure, expressed in terms of metabolic equivalents or METs. The resulting values for each woman were added to yield an MET-hours-per-week score. Reported diagnoses of colon cancer were confirmed by review of hospital records and pathology reports. Relative risks and associated 95% confidence intervals were calculated.
In multivariate analyses that included body mass index, women who expended more than 21 MET-hours per week on leisure-time physical activity had a relative risk of colon cancer of 0.54 (95% confidence interval [CI] = 0.33-0.90) in comparison with women who expended less than 2 MET-hours per week. Women who had a body mass index greater than 29 kg/m2 had a relative risk of colon cancer of 1.45 (95% CI = 1.02-2.07) in comparison with women who had a body mass index less than 21 kg/m2. A tendency toward higher colon cancer risk was observed for increasing waist-to-hip ratio (relative risk = 1.48 [95% CI = 0.88-2.49] for comparison of the highest quintile ratio [>0.833] to the lowest [<0.728]).
The significant inverse association between leisure-time physical activity and incidence of colon cancer in women in this study is consistent with what has been found in men. Recommendations to increase physical activity and maintain lean body weight should receive greater emphasis as part of a feasible approach to the prevention of colon cancer.
缺乏体育锻炼和高体重指数（体重千克数除以身高米数的平方）与结肠癌风险增加有关。然而，为数不多的针对女性的前瞻性研究均未显示休闲时间体育活动增加与结肠癌发病率或死亡率的显著降低存在统计学关联。
在这项前瞻性研究中，我们探讨休闲时间体育活动、体重指数或体脂分布是否会显著影响女性患结肠癌的风险。
本研究的参与者来自始于1976年的护士健康研究。每两年，这些女性提供额外的个人信息以及医学风险因素和重大医疗事件的信息。确定她们每周花在各种休闲体育活动上的时间，并将每项活动所花时间乘以其典型能量消耗，以代谢当量或梅脱（METs）表示。将每位女性的所得值相加，得出每周梅脱小时数得分。通过查阅医院记录和病理报告来确认所报告的结肠癌诊断。计算相对风险及相关的95%置信区间。
在纳入体重指数的多变量分析中，每周休闲时间体育活动消耗超过21梅脱小时的女性患结肠癌的相对风险为0.54（95%置信区间[CI]=0.33 - 0.90），而每周消耗少于2梅脱小时的女性。体重指数大于29kg/m²的女性患结肠癌的相对风险为1.45（95%CI = 1.02 - 2.07），而体重指数小于21kg/m²的女性。随着腰臀比增加，观察到结肠癌风险有升高趋势（最高五分位数比值[>0.833]与最低比值[<0.728]相比，相对风险 = 1.48 [95%CI = 0.88 - 2.49]）。
本研究中女性休闲时间体育活动与结肠癌发病率之间显著的负相关与在男性中发现的情况一致。作为预防结肠癌的可行方法的一部分，应更加强调增加体育活动和保持瘦体重的建议。
