Obesity Is Linked to at Least 13 Types of Cancer
A review of more than a thousand studies has found solid evidence that being overweight or obese increases the risk for at least 13 types of cancer. The study was conducted by a working group of the International Agency for Research on Cancer, part of the World Health Organization.
一篇涵盖了上千份研究的评论报告发现了确凿证据：超重或肥胖会增加至少13种癌症的患病风险。进行这项研究的工作团队来自于隶属世界卫生组织(World Health Organization)的国际癌症研究组织(International Agency for Research on Cancer)。
Strong evidence was already available to link five cancers to being overweight or obese: adenocarcinoma of the esophagus; colorectal cancer; breast cancer in postmenopausal women; and uterine and kidney cancers.
This new review, published in The New England Journal of Medicine, links an additional eight cancers to excess fat: gastric cardia, a cancer of the part of the stomach closest to the esophagus; liver cancer; gallbladder cancer; pancreatic cancer; thyroid cancer; ovarian cancer; meningioma, a usually benign type of brain cancer; and multiple myeloma, a blood cancer.
这篇刚刚发表在《新英格兰医学杂志》(New England Journal of Medicine)的评论还指出，另有八种癌症也与人体积蓄过多脂肪有关，分别是贲门癌（在胃与食道连接处产生的癌症）、肝癌、膀胱癌、胰脏癌、甲状腺癌、卵巢癌、脑膜瘤（一种通常为良性的脑癌），以及多发性骨髓癌（血癌的一种）。
According to the chairman of the working group, Dr. Graham Colditz, a professor of medicine and surgery at Washington University in St. Louis, these 13 cancers together account for 42 percent of all new cancer diagnoses.
该工作团队主席格雷厄姆‧寇迪兹博士(Dr. Graham Colditz)是圣路易斯华盛顿大学(Washington University in St. Louis)的内外全科教授，他表示，这13种癌症加起来占了所有新发癌症诊断的42%。
“Only smoking comes close” as an environmental factor affecting cancer risk, Dr. Colditz said. “And that’s an important message for nonsmokers. Obesity now goes to the top of the list of things to focus on.”
Obesity is associated with significant metabolic and hormone abnormalities, and with chronic inflammation, factors that may help explain its link to cancer.
Elizabeth A. Platz, a professor of epidemiology at the Johns Hopkins Bloomberg School of Public Health and a widely published cancer researcher who was not involved in the report, said that this was a “high-caliber working group of respected epidemiologists and laboratory researchers,” and that women in particular should take note of the results.
伊莉莎白‧A‧普拉兹(Elizabeth A. Platz)是约翰·霍普金斯大学布隆博格公共卫生学院(Johns Hopkins Bloomberg School of Public Health)的流行病学教授，也是发表了许多研究成果的癌症专家，她没有参与撰写这份评论，不过她表示这是一个“由备受敬重的流行病学家与实验室研究人员组成的高素质工作团队”，女性尤其要注意该报告的结论。
“The strongest association they found,” she said, “is with uterine cancer. And postmenopausal breast cancer is also connected to obesity, especially estrogen receptor positive cancer. These are important messages that women need to hear.”
Most of the studies the researchers looked at were observational so can’t prove cause and effect, though researchers considered evidence sufficient if an association could not be explained by chance, bias or other confounding factors. And most compared any increases in risk to that of an adult of normal weight having a body mass index of 18.5 to 24.9.
这些专家学者所检视的大多都是观察型研究，所以不能证明肥胖与这些癌症有因果关系，不过他们认为其间的相关性若没有其他意外、偏差或混淆因素的话，证据已经足够。而大部分癌症风险增加的情形，都是与体重正常、身体质量指数(body mass index, BMI)介于18.5与24.9之间的成人比较出来的结果。
For some cancers, the group found that the fatter the person, the greater the risk. In endometrial cancer, for example, compared with a woman of normal weight, one with a B.M.I. of 25 to 25.9 was at a 50 percent higher relative risk. But her risk more than doubled at B.M.I.s between 30 and 34.9 and more than quadrupled at B.M.I.s of 35 to 39.9. A woman with a B.M.I. of 40 or more was at seven times the risk for endometrial cancer as a woman of normal weight.
The group found only limited evidence that obesity could be linked to three additional types of cancer: male breast cancer; prostate cancer; and diffuse large B-cell lymphoma, the most common form of non-Hodgkin’s lymphoma.
They found no adequate evidence to link obesity with squamous-cell esophageal cancer, gastric noncardia cancer, cancer of the biliary tract, lung cancer, cutaneous melanoma, testicular cancer, urinary tract cancer, or glioma of the brain or spinal cord.
Does losing weight reduce the risk? Although animal studies suggest that it does, Dr. Colditz said, “it’s hard to study in humans because so few people lose weight and keep it off. But the priority of avoiding weight gain is the first thing we need to address.”