Re: Physical activity and risks of proximal and distal colon cancers: a systematic review and meta-analysis.
Re: Physical activity and risks of proximal and distal colon cancers: a systematic review and meta-analysis.
复制标题
回复：体力活动与近端和远端结肠癌的风险：系统评价和荟萃分析。
DOI：
--
复制
发表时间：
2013
期刊：
影响因子：
--
通讯作者：
Xiubo Jiang
中科院分区：
文献类型：
--
作者：
Dongfeng Zhang;Yili Wu;Wenjie Jiang;Xiubo Jiang
我们非常感兴趣地阅读了Boyle等人(1)关于体力活动与近端结肠癌（PCCs）和远端结肠癌（DCCs）风险的系统综述和荟萃分析，假设PCCs和dcc可能是两种不同的癌症类型，具有不同的遗传和环境风险因素。结果表明，体育活动与降低PCCs和dcc的风险有关。这是一项非常重要的调查，因为结直肠癌是男性和女性中第三大常见癌症(2)。然而，作为他们研究的一个局限性，作者指出，未来的研究应该关注体育活动的强度是否影响体育活动与结肠癌风险之间的关系，Barton(3)在最近的文章中也强调了这一点。最近，我们发表了一篇关于体力活动与乳腺癌风险的系统综述和荟萃分析(4)，发现体力活动强度影响其与乳腺癌风险的关联。因此，在这封信中，我们探讨体力活动强度是否影响其与PCCs和dcc风险的关联。正如Orsini等人(5)所描述的那样，考虑到研究间的异质性，进行了一项两阶段、随机效应、剂量反应的荟萃分析。简单地说，在体力活动水平的第25、第50和第75百分位数处的三个结首先使用广义最小二乘回归在限制三次样条模型中估计，考虑到每组公布的相对风险之间的相关性。然后进行多变量随机效应荟萃分析，使用限制最大似然法将研究特定估计结合起来。代谢当量（MET）是最常用的体力活动强度测量方法(6)。因此，如果研究提供以下信息(7)，则纳入研究：三个或更多定量类别（METhours）的相对风险（95%置信区间（CI））（我们为简单起见提供了相对风险的所有结果），以及每个类别的病例数和参与者（或人年）。每个类别的中位数或平均体力活动水平被分配给每个研究的相应相对风险。对于PCC，使用了Boyle等人(1)研究中的7项研究[文献（9,19,20,27,32,33,39）]的数据，其中包括1534例PCC病例受试者。发现线性关系，PCC的风险分别为0.97 （95% CI = 0.90至1.04）、0.94 （95% CI = 0.83至1.07）、0.90 （95% CI = 0.77至1.03）、0.85 （95% CI = 0.73至0.98）、0.79 （95% CI = 0.67至0.93）和0.74 (95% CI = 0.59至0.92)，分别为10、20、30、40、50和60 MET-hours/week（图1）。对于DCC，使用了上述7项研究的数据，其中包括1583例DCC病例。发现了一些非线性关系的证据，DCC的风险分别为0.90 （95% CI = 0.83 ~ 0.96）、0.80 （95% CI = 0.69 ~ 0.92）、0.77 （95% CI = 0.67 ~ 0.91）、0.81 （95% CI = 0.70 ~ 0.93）、0.84 （95% CI = 0.71 ~ 0.99）和0.86 (95% CI = 0.70 ~ 1.06)，分别为10、20、30、40、50和60小时/周。
We read with great interest the systematic review and meta-analysis by Boyle et al. (1) on physical activity and risks of proximal colon cancers (PCCs) and distal colon cancers (DCCs), under the hypothesis that PCCs and DCCs may be two distinct cancer types with different genetic and environmental risk factors. The results suggested that physical activity is associated with a reduced risk of both PCCs and DCCs. This is a very important investigation because colorectal cancer is the third most common cancer in both men and women (2). However, as a limitation of their study, the authors stated that future research should focus on whether the intensity of physical activity influences the association between physical activity and the risk of colon cancer, which was also stressed in the recent article by Barton (3). Recently, we published a systematic review and metaanalysis (4) on physical activity and risk of breast cancer and found that intensity of physical activity influences its association with the risk of breast cancer. Thus, in this letter, we explore whether the intensity of physical activity influences its association with the risk of PCCs and DCCs. A two-stage, random-effects, dose– response meta-analysis taking into account the between-study heterogeneity was performed, as has been well described by Orsini et al. (5). Briefly, three knots at the 25th, 50th, and 75th percentiles of the levels of physical activity were first estimated in a restricted cubic spline model using generalized least square regression taking into account the correlation within each set of published relative risk. Then a multivariable random-effects meta-analysis was conducted to combine the study-specific estimates using the restricted maximum likelihood method. Metabolic equivalent (MET) is the most commonly used measurement of physical activity intensity (6). Thus studies were included if they provided the following information (7): relative risk with 95% confidence interval (CI) for three or more quantitative categories (METhours) of physical activity (we presented all results with relative risk for simplicity), as well as the number of cases and participants (or person-years) for each category of physical activity. The median or mean level of physical activity for each category was assigned to the corresponding relative risk for every study. For PCC, data from seven studies [references (9,19,20,27,32,33,39) in the study by Boyle et al. (1)], which included 1534 PCC case subjects, were used. A linear relationship was found, and the risk of PCC was 0.97 (95% CI = 0.90 to 1.04), 0.94 (95% CI = 0.83 to 1.07), 0.90 (95% CI = 0.77 to 1.03), 0.85 (95% CI = 0.73 to 0.98), 0.79 (95% CI = 0.67 to 0.93), and 0.74 (95% CI = 0.59 to 0.92) for 10, 20, 30, 40, 50, and 60 MET-hours/week, respectively (Figure 1). For DCC, data from the above-mentioned seven studies, which included 1583 DCC case subjects, were used. Some evidence of a nonlinear relationship was found, and the risk of DCC was 0.90 (95% CI = 0.83t o 0.96), 0.80 (95% CI = 0.69 to 0.92), 0.77 (95% CI = 0.67 to 0.91), 0.81 (95% CI = 0.70 to 0.93), 0.84 (95% CI = 0.71 to 0.99), and 0.86 (95% CI = 0.70 to 1.06) for 10, 20, 30, 40, 50, and 60 METhours/week, respectively.
影响因子：
5.6
作者：
Slattery, ML;Edwards, SL;Potter, JD
通讯作者：
Potter, JD
影响因子：
5
作者：
Orsini, Nicola;Li, Ruifeng;Spiegelman, Donna
通讯作者：
Spiegelman, Donna