Drinkard C R, Sellers T A, Potter J D, Zheng W, Bostick R M, Nelson C L, Folsom A R
Division of Epidemiology, School of Public Health, University of Minnesota, Minneapolis 55454-1015, USA.
Am J Epidemiol. 1995 Sep 15;142(6):600-7. doi: 10.1093/oxfordjournals.aje.a117681.
Obesity has been associated with an increased risk of cancer at a number of sites. A notable exception appears to be lung cancer, for which several studies suggest a modest inverse association. However, cigarette smoking is directly associated with lung cancer and inversely associated with body mass index. To investigate the hypothesis that body mass index is associated with lung cancer independent of cigarette smoking, the authors analyzed data from a prospective cohort study of 41,837 Iowa women aged 55-69 years at baseline in 1986. In addition, they examined whether central adiposity (high waist/hip ratio) was associated with lung cancer incidence. Through 1992 (6 years of follow-up), 233 cases of lung cancer were identified through the State Health Registry of Iowa. The body mass index at several ages was calculated from self-reports of height at baseline and weights at ages 18, 30, 40, and 50 years and at baseline. Current and former smokers generally had lower mean body mass indices than did nonsmokers at all ages except 18 years. Cases generally had lower body mass indices than did noncases at all ages except 18 and 30 years but, among current smokers, cases had higher mean body mass indices than did noncases at all ages except baseline, although the differences were not statistically significant. An apparent positive association of a high waist/hip ratio with lung cancer in the total cohort was found to be primarily accounted for by a higher waist/hip ratio in current and former smokers. When stratified by smoking status and adjusted for other risk factors, including age and pack-years of smoking, the body mass index at baseline, body mass index at age 50 years, and waist/hip ratio were not associated with lung cancer. The results of multivariate analyses suggest that the inverse association of body mass index with lung cancer can be explained by smoking status and that the positive association of waist/hip ratio with lung cancer can be explained by pack-years of smoking.
肥胖与多个部位患癌风险增加有关。一个显著的例外似乎是肺癌，多项研究表明二者存在适度的负相关。然而，吸烟与肺癌直接相关，与体重指数呈负相关。为了研究体重指数与肺癌的关联是否独立于吸烟，作者分析了一项前瞻性队列研究的数据，该研究于1986年对41837名年龄在55 - 69岁的爱荷华州女性进行了基线调查。此外，他们还研究了中心性肥胖（高腰臀比）是否与肺癌发病率相关。到1992年（随访6年），通过爱荷华州州立健康登记处确定了233例肺癌病例。根据研究对象在基线时自报的身高以及18岁、30岁、40岁、50岁时和基线时的体重，计算出几个年龄段的体重指数。除了18岁，当前吸烟者和既往吸烟者在所有年龄段的平均体重指数通常都低于不吸烟者。除了18岁和30岁，病例在所有年龄段的体重指数通常都低于非病例，但在当前吸烟者中，除了基线外，病例在所有年龄段的平均体重指数都高于非病例，尽管差异无统计学意义。在整个队列中，高腰臀比与肺癌之间明显的正相关主要是由当前吸烟者和既往吸烟者较高的腰臀比所致。按吸烟状况分层并对包括年龄和吸烟包年数在内的其他风险因素进行调整后，基线时的体重指数、50岁时的体重指数和腰臀比与肺癌均无关联。多变量分析结果表明，体重指数与肺癌之间的负相关可由吸烟状况解释，腰臀比与肺癌之间的正相关可由吸烟包年数解释。
