英國醫(yī)生研究了近3萬癌癥病例后發(fā)現(xiàn),，體重超標(biāo)將提升20多種癌癥的發(fā)病率,。領(lǐng)導(dǎo)這項研究的科學(xué)家，英國曼徹斯特大學(xué)的安德魯-雷內(nèi)漢（Andrew Renehan）將研究結(jié)果發(fā)表在了著名醫(yī)學(xué)雜志《柳葉刀》雜志上,。
與此同時,，在美國波士頓召開的美國科學(xué)促進會的年會上，哈佛大學(xué)公共衛(wèi)生學(xué)院的營養(yǎng)專家沃爾特-維列特（Walter Willett ）預(yù)言,，肥胖將迅速取代吸煙,，成為首要的致癌因素，尤其是在發(fā)展中國家,。他列舉了很多例子——既有動物試驗也有人體試驗,，有些已經(jīng)完成有些還在進行中，而這些例子都證明,，維列特的預(yù)言絕非信口開河,。
維列特說：“目前，至少有20％的癌癥與肥胖有關(guān),，吸煙導(dǎo)致的癌癥則占所有癌癥的30％左右,，肥胖與吸煙的致癌率越來越接近。但在美國,，吸煙的人已經(jīng)越來越少,，而肥胖人數(shù)卻在迅速增加，因此,，要不了多久,，肥胖的致癌率就會超過吸煙的致癌率,。“
曾有研究表明，當(dāng)一個人到了75歲,，或者更大年齡時,，稍微長胖點有助延長壽命，降低死亡幾率,。不少科學(xué)家認為,，上述結(jié)論其實并沒有科學(xué)依據(jù)，但還是有醫(yī)生給出了“合理”的解釋：如果一個老人偏瘦,，說明他正受到疾病的困擾,，體重稍微超標(biāo)，則有助于抵抗一些常見疾病,。
2006年,，美國南加利福尼亞大學(xué)的科學(xué)家做了一項研究,，他們發(fā)現(xiàn)在80歲以上的老年人中,，體重稍微超標(biāo)的人，死亡率比其他老年人更低,。但在同一項研究中,，在20歲出頭的年輕人中，體重超標(biāo)或肥胖的人,，死亡率卻是同齡人中最高的,。
這項研究的關(guān)鍵在于，老年人應(yīng)該超重多少最合適,？遺憾的是,，他們并沒有找到答案，因為在80歲以上的老年人中,，幾乎沒有肥胖者了,。
的確，多長肉有助于癌癥患者抵抗化療等帶來的創(chuàng)傷,，但對于任何人來說,，不患癌癥可能更實際也更令人高興，而達到這個目標(biāo)的第一件事,，就是保持苗條的身材,。
不過需要注意的是，瘦只能降低患癌幾率,，而不是完全排除這種可能性,。如果不相信本文的觀點，可以去找找看,，有沒有90多歲的肥胖老人,。
生物谷推薦原始出處：
The Lancet 2008; 371:569-578
DOI:10.1016/S0140-6736(08)60269-X
Body-mass index and incidence of cancer: a systematic review and meta-analysis of prospective observational studies
Dr Andrew G Renehan PhD, Margaret Tyson PhD, Matthias Egger MD, Richard F Heller MD and Marcel Zwahlen PhD
Summary
Background
Excess bodyweight, expressed as increased body-mass index (BMI), is associated with the risk of some common adult cancers. We did a systematic review and meta-analysis to assess the strength of associations between BMI and different sites of cancer and to investigate differences in these associations between sex and ethnic groups.
Methods
We did electronic searches on Medline and Embase (1966 to November 2007), and searched reports to identify prospective studies of incident cases of 20 cancer types. We did random-effects meta-analyses and meta-regressions of study-specific incremental estimates to determine the risk of cancer associated with a 5 kg/m2 increase in BMI.
Findings
We analysed 221 datasets (141 articles), including 282?137 incident cases. In men, a 5 kg/m2 increase in BMI was strongly associated with oesophageal adenocarcinoma (RR 1·52, p<0·0001) and with thyroid (1·33, p=0·02), colon (1·24, p<0·0001), and renal (1·24, p <0·0001) cancers. In women, we recorded strong associations between a 5 kg/m2 increase in BMI and endometrial (1·59, p<0·0001), gallbladder (1·59, p=0.04), oesophageal adenocarcinoma (1·51, p<0·0001), and renal (1·34, p<0·0001) cancers. We noted weaker positive associations (RR <1·20) between increased BMI and rectal cancer and malignant melanoma in men; postmenopausal breast, pancreatic, thyroid, and colon cancers in women; and leukaemia, multiple myeloma, and non-Hodgkin lymphoma in both sexes. Associations were stronger in men than in women for colon (p<0·0001) cancer. Associations were generally similar in studies from North America, Europe and Australia, and the Asia–Pacific region, but we recorded stronger associations in Asia–Pacific populations between increased BMI and premenopausal (p=0·009) and postmenopausal (p=0·06) breast cancers.
