Impact of Bariatric Surgery on Cancer Incidence in Severely Obese Adults

描述（由申请人提供）：严重肥胖影响着超过1500万美国成年人，是发展某些类型癌症的一个公认的危险因素。2007年，肥胖导致大约50,500例女性新发癌症病例和34,000例男性新发癌症病例。肥胖被认为是几种癌症的一个公认的风险因素。然而，专门研究有意减肥是否能降低癌症风险的临床试验还没有完成，观察性研究的数据也很少，缺乏说服力。目前，减肥手术是唯一被证实的治疗严重肥胖患者持续减肥的方法，并且伴随代谢过程的立即改变，这也可能影响癌症的生长。最近的观察性研究表明，减肥手术可以降低癌症的发病率，但要么使用过时的程序，要么没有得到充分的控制。需要进行研究来确定有意减肥是否可以降低癌症风险，以帮助激励和指导未来有关美国体重管理项目实施的研究和政策决策。本项目的目标是：1)评估减肥手术与非手术治疗对严重肥胖患者（所有类型）癌症发病率的影响；2)探讨手术后癌症风险的降低是否由体重减轻介导；3)确定哪些患者特征与严重肥胖患者癌症发病率的降低最密切相关。本研究将利用来自HMO研究网络（HMORN）中五个大型综合健康计划和医疗服务系统的电子管理、医疗记录数据库和癌症登记处的数据，来评估减肥手术对严重肥胖患者癌症预后的长期影响。我们将评估2005-2012年期间接受任何类型减肥手术的严重肥胖（BMI为e35）患者与同期未接受减肥手术的严重肥胖患者的癌症发病率。主要的比较将使用对照人群进行减肥手术的倾向和发生意外癌症的倾向相匹配。额外的分析将探讨减肥手术对严重肥胖妇女癌症（所有类型和肥胖特定类型）发病率的影响，以及年龄、种族/民族和减肥手术类型治疗效果的异质性。这项拟议中的研究将利用比较有效性研究的最新进展，确定显著减肥是否能降低癌症发病率。通过确定风险的变化是否由体重减轻介导，我们将能够深入了解手术后降低癌症发病率的潜在机制。

DESCRIPTION (provided by applicant): Severe obesity affects over 15 million U.S. adults and is a well-established risk factor for developing some types of cancer. In 2007, obesity was responsible for approximately 50,500 new cases of cancer in women and 34,000 new cases in men. Obesity is a considered a well-established risk factor for several types of cancer. However, clinical trials to specifically examine whether intentional weight loss reduces cancer risk have not been done and data from observational studies is sparse and less convincing. Currently, bariatric surgery is the only proven treatment for sustained weight loss in the severely obese patient and is accompanied by immediate alterations of metabolic processes that may also influence cancer growth. Recent observational studies have suggested that bariatric surgery can decrease the incidence of cancer but have either used outdated procedures or have not been adequately controlled. Research is needed to establish whether intentional weight loss can reduce cancer risk to help motivate and guide future research and policy decisions regarding implementation of weight management programs in the US. The goals of this project are 1) estimate the impact of bariatric surgery versus non-surgical treatment on the incidence of cancer (all types) in severely obese patients, 2) explore whether the reduction in risk of cancer after surgery is mediated by weight loss, and 3) determine which patient characteristics are most strongly associated with a reduction in cancer incidence in severely obese patients. This study will utilize data from electronic administrative, medical record databases, and cancer registries from five large, integrated health plans and care delivery systems in the HMO Research Network (HMORN) to estimate the long-term impact of bariatric surgery on cancer outcomes among severely obese patients. We will estimate the incidence of cancer among severely obese (BMI e35) patients who underwent bariatric surgery of any type from 2005-2012 compared to severely obese patients who did not undergo bariatric surgery during the same time period. Main comparisons will use a control population matched by both the propensity for bariatric surgery and the propensity for developing incident cancer. Additional analyses will explore the impact of bariatric surgery on the incidence of cancer (all types and obesity specific types) in severely obese women and the heterogeneity of treatment effects by age, race/ethnicity, and bariatric surgery type. The proposed research will determine whether significant weight loss can reduce cancer incidence using the latest advances in comparative effectiveness research. We will be able to provide insight into potential mechanisms of reducing cancer incidence following surgery by identifying whether the change in risk is mediated by weight loss.