Department of thoracic surgery, Shangqiu First People's Hospital, Shangqiu, 476100, Henan, China.
Department of Thoracic and Cardiovascular Surgery, the First Affiliated Hospital of Henan University, No. 357 Ximen Street, Kaifeng City, 475000, Henan Province, China.
BMC Cancer. 2018 Jun 5;18(1):635. doi: 10.1186/s12885-018-4543-y.
Obesity is found to increase the risk of most cancer types, but reduce lung cancer risk in many studies. However, the association between obesity and lung cancer is still controversial, mainly owing to the confounding effect of smoking.
Eligible studies were identified from electric databases to July 1, 2017. Relevant data were extracted and pooled using random-effects models; dose-response and subgroup analyses were also performed.
Twenty-nine studies with more than 10,000 lung cancer cases in15 million never smokers were included. Compared with normal weight, the summary relative risk (RR) was 0.77(95% confidence interval [CI]: 0.68-0.88, P < 0.01) for excess body weight (body mass index [BMI] ≥ 25 kg/m). An inverse linear dose-response relationship was observed between BMI and lung cancer risk in never smokers, with an RR of 0.89(95% CI: 0.84-0.95, P < 0.01) per 5 kg/m increment in BMI. The results remained stable in most subgroup analyses. However, when stratified by sex, a significant inverse association existed in women but not in men. Similar results were found in analyses for other categories of BMI.
Our results indicate that higher BMI is associated with lower lung cancer risk in never smokers.
肥胖被发现会增加大多数癌症类型的风险，但在许多研究中会降低肺癌风险。然而，肥胖与肺癌之间的关联仍然存在争议，主要是由于吸烟的混杂影响。
从电子数据库中检索到 2017 年 7 月 1 日之前的合格研究。使用随机效应模型提取和汇总相关数据；还进行了剂量-反应和亚组分析。
纳入了 29 项研究，这些研究涉及 1500 万从不吸烟者中的超过 10000 例肺癌病例。与正常体重相比，超重者（体重指数[BMI]≥25 kg/m²）的汇总相对风险（RR）为 0.77（95%置信区间[CI]：0.68-0.88，P<0.01）。从不吸烟者中，BMI 与肺癌风险之间存在负相关的线性剂量-反应关系，BMI 每增加 5 kg/m²，RR 为 0.89（95% CI：0.84-0.95，P<0.01）。在大多数亚组分析中，结果仍然稳定。然而，按性别分层时，女性存在显著的负相关关系，而男性则不存在。BMI 的其他分类的分析结果也相似。
我们的结果表明，较高的 BMI 与从不吸烟者的肺癌风险较低相关。
