ImportanceObesity and insulin are risk factors for breast cancer, and retrospective studies suggest bariatric surgery reduces breast cancer risk in women. However, long-term prospective data on breast cancer risk after bariatric surgery and the role of baseline insulin levels are lacking.ObjectiveTo examine if bariatric surgery is associated with breast cancer incidence in women and if treatment benefit is modified by baseline insulin levels.Design, Setting, and ParticipantsThe Swedish Obese Subjects (SOS) study was a nonrandomized intervention trial designed to investigate the long-term effects of bariatric surgery on obesity-related mortality and morbidity. Study recruitment took place between 1987 and 2001, and median (IQR) follow-up time was 23.9 years (20.1-27.1) years. The study was conducted at 25 public surgical departments and 480 primary health care centers in Sweden and included 2867 women aged 37 to 60 years and with body mass index 38 or greater (calculated as weight in kilograms divided by height in meters squared).InterventionIn the surgery group (n = 1420), 260 women underwent gastric banding, 970 vertical banded gastroplasty, and 190 gastric bypass. The remaining contemporaneously matched control individuals (n = 1447) received usual obesity care.Main Outcome and MeasuresBreast cancer, the main outcome of this secondary report, was not a predefined outcome in the SOS study. Breast cancer events were identified in the Swedish National Cancer Registry.ResultsThe study population comprised 2867 women with a mean (SD) age of 48.0 (6.2) years. During follow-up, there were 154 breast cancer events, 66 in the surgery group and 88 in the usual care group, and a decreased risk of breast cancer was observed in the bariatric surgery group (hazard ratio [HR], 0.68; 95% CI, 0.49–0.94; P = .019; adjusted HR, 0.72; 95% CI, 0.52-1.01; P = .06). The surgical treatment benefit on breast cancer risk was greater in women with baseline insulin levels above the median 15.8 μIU/L (HR, 0.48; 95% CI, 0.31-0.74; P = .001; adjusted HR, 0.55; 95% CI, 0.35-0.86; P = .008) compared to those below (HR, 0.95; 95% CI, 0.59-1.53; P = .84; adjusted HR, 1.01; 95% CI, 0.61-1.66; P = .97; interaction P = .02).Conclusions and RelevanceThis prospective clinical trial indicated a reduced risk of breast cancer after bariatric surgery in women with obesity. The surgical treatment benefit was predominantly seen in women with hyperinsulinemia.Trial RegistrationClinicalTrials.gov Identifier: NCT01479452

中文翻译：

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减肥手术后的乳腺癌风险和胰岛素水平的影响


重要性肥胖和胰岛素是乳腺癌的危险因素，回顾性研究表明减肥手术可降低女性患乳腺癌的风险。然而，缺乏关于减肥手术后乳腺癌风险和基线胰岛素水平作用的长期前瞻性数据。目的检查减肥手术是否与女性乳腺癌发病率相关，以及治疗效果是否会因基线胰岛素水平而改变。设置和参与者瑞典肥胖受试者（SOS）研究是一项非随机干预试验，旨在调查减肥手术对肥胖相关死亡率和发病率的长期影响。研究招募发生在 1987 年至 2001 年间，中位随访时间 (IQR) 为 23.9 年 (20.1-27.1) 年。该研究在瑞典 25 个公共外科部门和 480 个初级卫生保健中心进行，纳入了 2867 名年龄在 37 岁至 60 岁、体重指数为 38 或更高（计算方法为体重公斤数除以身高米数平方）的女性。手术组（n = 1420）中，260 名女性接受了胃束带术，970 名女性接受了垂直束带胃成形术，190 名女性接受了胃绕道术。其余同时匹配的对照个体 (n = 1447) 接受常规肥胖护理。 主要结果和措施乳腺癌是本次报告的主要结果，并不是 SOS 研究中的预定结果。瑞典国家癌症登记处确定了乳腺癌事件。结果研究人群包括 2867 名女性，平均 (SD) 年龄为 48.0 (6.2) 岁。随访期间，共发生 154 起乳腺癌事件，其中手术组 66 起，常规护理组 88 起，并且减肥手术组观察到乳腺癌风险降低（风险比 [HR]，0.68； 95% CI，0.49–0.94； P = .019；调整后心率，0.72； 95% CI，0.52-1.01； P = .06)。对于基线胰岛素水平高于中位数 15.8 μIU/L 的女性，手术治疗对乳腺癌风险的益处更大（HR，0.48；95% CI，0.31-0.74；P = 0.001；调整后 HR，0.55；95% CI， 0.35-0.86；P = .008）与以下值相比（HR，0.95；95% CI，0.59-1.53​​；P = .84；调整后的 HR，1.01；95% CI，0.61-1.66；P = .97；交互作用P = .02）。结论和相关性这项前瞻性临床试验表明，肥胖女性在接受减肥手术后患乳腺癌的风险降低。手术治疗的益处主要见于患有高胰岛素血症的女性。试验注册临床试验。政府标识符：NCT01479452