肥胖更易致癌 而且不止一種大綱

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.

一篇涵蓋了上千份研究的評論報告發現了確鑿證據：超重或肥胖會增加至少13種癌症的患病風險。進行這項研究的工作團隊來自於隸屬世界衛生組織(World Health Organization)的國際癌症研究組織(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.

該團隊已發現食道腺癌、結腸直腸癌、絕經期乳腺癌、子宮癌及腎癌五種癌症與超重或肥胖相關的有力證據。

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;

這篇剛剛發表在《新英格蘭醫學雜誌》(New England Journal of Medicine)的評論還指出，另有八種癌症也與人體積蓄過多脂肪有關，

liver cancer; gallbladder cancer; pancreatic cancer; thyroid cancer; ovarian cancer; meningioma, a usually benign type of brain cancer; and multiple myeloma, a blood cancer.

分別是賁門癌（在胃與食道連接處產生的癌症）、肝癌、膀胱癌、胰臟癌、甲狀腺癌、卵巢癌、腦膜瘤（一種通常爲良性的腦癌），以及多發性骨髓癌（血癌的一種）。

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.

該工作團隊主席格雷厄姆‧寇迪茲博士(Dr. Graham Colditz)是聖路易斯華盛頓大學(Washington University in St. Louis)的內外全科教授，他表示，這13種癌症加起來佔了所有新發癌症診斷的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.”

寇迪茲說，作爲會影響癌症風險的環境因素，“只有抽菸能（與肥胖）相提並論。這對不抽菸的人來說是重大警訊。如今肥胖問題在所有注意事項裏面排第一了。”

Obesity is associated with significant metabolic and hormone abnormalities, and with chronic inflammation, factors that may help explain its link to cancer.

肥胖與代謝及荷爾蒙顯著異常還與慢性炎症相關，而這些因素或許能幫助解釋肥胖爲何與癌症有關。

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,

伊莉莎白‧A‧普拉茲(Elizabeth A. Platz)是約翰•霍普金斯大學布隆博格公共衛生學院(Johns Hopkins Bloomberg School of Public Health)的流行病學教授，也是發表了許多研究成果的癌症專家，她沒有參與撰寫這份評論，

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.

不過她表示這是一個“由備受敬重的流行病學家與實驗室研究人員組成的高素質工作團隊”，女性尤其要注意該報告的結論。

“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.”

“他們發現有最強烈關聯的，”普拉茲說，“是子宮癌。絕經期乳腺癌也與肥胖有關，特別是雌激素受體檢驗呈陽性的癌症。女性同胞要把這些重要訊息聽進去。”

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.

這些專家學者所檢視的大多都是觀察型研究，所以不能證明肥胖與這些癌症有因果關係，不過他們認爲其間的相關性若沒有其他意外、偏差或混淆因素的話，證據已經足夠。

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.

而大部分癌症風險增加的情形，都是與體重正常、身體質量指數(body mass index, BMI)介於18.5與24.9之間的成人比較出來的結果。

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.

該研究團隊發現，人越胖，罹患某些癌症的風險就越高。拿子宮內膜癌來當例子，與體重正常的女性相較，一個BMI指數介於25與25.9之間的女性罹患此種癌症的相對風險提高了50%。

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.

當她的BMI指數達30到34.9之間，罹病風險達兩倍；BMI指數介於35到39.9之間，風險則是4倍。一位BMI指數達到或超過40的女性，罹患此症的風險是體重正常女性的7倍。

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.

至於肥胖與男性乳腺癌、前列腺癌、瀰漫性大B細胞淋巴癌（最常見的一種非霍奇金氏淋巴癌）這另外三種癌症的關聯，該團隊僅找到有限證據。

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.

食道鱗狀細胞癌、非賁門型胃癌、膽道癌、肺癌、黑色素皮膚癌、睪丸癌、尿道癌、腦部或脊髓膠質母細胞瘤這幾種癌症，他們則沒有找到足夠證據支持其與肥胖有關。

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.”

減重是否可以降低風險？雖然動物研究的結果顯示可以，但寇迪茲博士表示：“我們很難對人類進行研究，因爲減重又保持不復胖的人太少了。讓民衆把避免體重增加當作要事來看待，是我們該最先着手的。”