Heo Moonseong, Kabat Geoffrey C, Strickler Howard D, Lin Juan, Hou Lifang, Stefanick Marcia L, Anderson Garnet L, Rohan Thomas E
1 Department of Epidemiology and Population Health, Albert Einstein College of Medicine , Bronx, New York.
J Womens Health (Larchmt). 2015 Mar;24(3):218-27. doi: 10.1089/jwh.2014.4977. Epub 2015 Jan 14.
Obesity is a risk factor for several cancers in postmenopausal women. We attempted to determine cutoffs of adiposity measures in relation to risk of obesity-related cancers among postmenopausal women and to examine the effects of hormone therapy (HT) use on the cutoffs, neither of which has been broadly studied.
We used data from the Women's Health Initiative cohort (n=144,701) and applied Cox-proportional hazards regressions to each combination of 17 cancer types and 6 anthropometric measures (weight, body mass index [BMI], weight to height ratio, waist circumference, waist to hip ratio [WHR], and waist to height ratio). Interactions between the anthropometric measures and HT use were also examined. Cutoffs were determined by applying a grid search followed by a two-fold cross validation method. Survival ROC analysis of 5- and 10-year incidence followed.
Breast, colorectal, colon, endometrium, kidney, and all cancers combined were significantly positively associated with all six anthropometric measures, whereas lung cancer among ever smokers was significantly inversely associated with all measures except WHR. The derived cutoffs of each obesity measure varied across cancers (e.g., BMI cutoffs for breast and endometrium cancers were 30 kg/m(2) and 34 kg/m(2), respectively), and also depended on HT use. The Youden indices of the cutoffs for predicting 5- and 10-year cancer incidence were higher among HT never users.
Using a panel of different anthropometric measures, we derived optimal cut-offs categorizing populations into high- and low-risk groups, which differed by cancer type and HT use. Although the discrimination abilities of these risk categories were generally poor, the results of this study could serve as a starting point from which to determine adiposity cutoffs for inclusion in risk prediction models for specific cancer types.
肥胖是绝经后女性患多种癌症的危险因素。我们试图确定绝经后女性肥胖相关癌症风险的肥胖测量指标临界值，并研究激素治疗（HT）的使用对这些临界值的影响，这两方面此前均未得到广泛研究。
我们使用了女性健康倡议队列（n = 144,701）的数据，并将Cox比例风险回归应用于17种癌症类型与6种人体测量指标（体重、体重指数[BMI]、体重身高比、腰围、腰臀比[WHR]和腰高比）的每种组合。还研究了人体测量指标与HT使用之间的相互作用。通过应用网格搜索法，随后采用两倍交叉验证法来确定临界值。接着进行了5年和10年发病率的生存ROC分析。
乳腺癌、结直肠癌、结肠癌、子宫内膜癌、肾癌以及所有癌症合并症与所有六种人体测量指标均呈显著正相关，而曾经吸烟者中的肺癌与除WHR外的所有指标均呈显著负相关。每种肥胖测量指标的推导临界值因癌症而异（例如，乳腺癌和子宫内膜癌的BMI临界值分别为30 kg/m²和34 kg/m²），并且还取决于HT的使用情况。在从未使用HT的人群中，预测5年和10年癌症发病率的临界值的约登指数更高。
通过一组不同的人体测量指标，我们得出了将人群分为高风险和低风险组的最佳临界值，这些临界值因癌症类型和HT使用情况而异。尽管这些风险分类组的判别能力总体较差，但本研究结果可作为确定肥胖临界值的起点，以便纳入特定癌症类型的风险预测模型。
