Mon, Nov 14, 2016 page9

• Obesity link with range of cancers 肥胖更致癌，而且不止一種

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  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.

  There is strong evidence showing a link between five cancers and being overweight or obese: adenocarcinoma of the esophagus; colorectal cancer; breast cancer in postmenopausal women; and uterine and kidney cancers.

  This new review 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 tumor; and multiple myeloma, a blood cancer.

  

  An overweight person eats in a London park in this photo taken on Oct 17, 2007. 一名體重過重的男子在倫敦的公園吃飯，攝於二○○七年十月十七日。

  Photo: AP
  照片：美聯社

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

  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 (BMI) of 18.5 to 24.9.

  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 BMI of 25 to 29.9 was at a 50 percent higher relative risk. But her risk more than doubled at BMIs between 30 and 34.9 and more than quadrupled at BMIs of 35 to 39.9. A woman with a BMI of 40 or more was at seven times the risk for endometrial cancer as a woman of normal weight.

  This article is an edited version of a piece that originally appeared in the New York Times Magazine

  (NEW YORK TIMES / Nicholas Bakalar)

  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十三種癌症的患病風險。

  有強力證據顯示食道腺癌、結腸直腸癌、停經後乳腺癌、子宮癌及腎癌五種癌症，與超重或肥胖相關。

  這篇報告還指出，另有八種癌症也與人體積蓄過多脂肪有關，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（一種通常為良性的腦癌），以及多發性骨髓癌（血癌的一種）。

  肥胖與代謝及荷爾蒙顯著異常還與慢性炎症相關，而這些因素或許有助解釋肥胖與癌症的關聯。

  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，不過他們認為其間的相關性若非純屬巧合、研究偏差或其他混淆因素的話，證據已經足夠。而大部分癌症風險增加的情形，都是與體重正常、身體質量指數介於十八點五與二十四點九之間的成人對照出來的結果。

  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，一個身體質量指數介於二十五與二十九點九之間的女性罹患此種癌症的相對風險提高了百分之五十。當她的身體質量指數達三十到三十四點九之間，罹病風險達兩倍；身體質量指數介於三十五到三十九點九之間，風險則是四倍。一位身體質量指數達到或超過四十的女性，罹患此症的風險是體重正常女性的七倍。

  本文為編輯後的版本，原文已於紐約時報雜誌刊登

  （紐約時報／林凱雄譯）
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