McTiernan Anne
Prevention Center, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA.
Oncology (Williston Park). 2005 Jun;19(7):871-81; discussion 881-2, 885-6.
Overweight and obesity increase the risk of developing several cancers. Once cancer develops, individuals may be at increased risk of recurrence and poorer survival if they are overweight or obese. A statistically significant association between overweight or obesity and breast cancer recurrence or survival has been observed in the majority of population-based case series; however, adiposity has been shown to have less of an effect on prognosis in the clinical trial setting. Weight gain after breast cancer diagnosis may also be associated with decreased prognosis. New evidence suggests that overweight/obesity vs normal weight may increase the risk of poor prognosis among resected colon cancer patients and the risk of chemical recurrence inprostate cancer patients. Furthermore, obese cancer patients are at increased risk for developing problems following surgery, including wound complication, lymphedema, second cancers, and the chronic diseases affecting obese individuals without cancer such as cardiovascular disease and diabetes. Mechanisms proposed to explain the association between obesity and reduced prognosis include adipose tissue-induced increased concentrations of estrogens and testosterone, insulin, bioavailable insulin-like growth factors, leptin, and cytokines. Additional proposed mechanisms include reduced immune functioning, chemotherapy dosing, and differences in diet and physical activity in obese and nonobese patients. There have been no randomized clinical trials testing the effect of weight loss on recurrence or survival in overweight or obese cancer patients, however. In the absence of clinical trial data, normal weight, overweight, and obese patients should be advised to avoid weight gain through the cancer treatment process. In addition, weight loss is probably safe, and perhaps helpful, for overweight and obese cancer survivors who are otherwise healthy.
超重和肥胖会增加患多种癌症的风险。一旦患上癌症，如果个体超重或肥胖，其复发风险可能会增加，生存率也可能更低。在大多数基于人群的病例系列研究中，已观察到超重或肥胖与乳腺癌复发或生存率之间存在统计学上的显著关联；然而，在临床试验环境中，肥胖对预后的影响较小。乳腺癌诊断后体重增加也可能与预后不良有关。新证据表明，超重/肥胖与正常体重相比，可能会增加接受手术切除的结肠癌患者预后不良的风险以及前列腺癌患者化学复发的风险。此外，肥胖的癌症患者术后出现问题的风险增加，包括伤口并发症、淋巴水肿、二次癌症以及影响无癌症肥胖个体的慢性疾病，如心血管疾病和糖尿病。提出的解释肥胖与预后不良之间关联的机制包括脂肪组织导致雌激素、睾酮、胰岛素、生物可利用的胰岛素样生长因子、瘦素和细胞因子浓度增加。其他提出的机制包括免疫功能降低、化疗剂量以及肥胖和非肥胖患者在饮食和身体活动方面的差异。然而，目前尚无随机临床试验来测试减肥对超重或肥胖癌症患者复发或生存的影响。在缺乏临床试验数据的情况下，应建议体重正常、超重和肥胖的患者在癌症治疗过程中避免体重增加。此外，对于其他方面健康的超重和肥胖癌症幸存者来说，减肥可能是安全的，甚至可能有益。
