一项针对新加坡华族的研究显示，过瘦人群与过胖人群一样，患结肠癌的风险均比较高。
据新加坡《海峡时报》3日报道，这项研究由新加坡国立大学和美国明尼苏达大学研究人员合作完成，研究对象是5万多名新加坡华族人，论文将刊登在美国《癌症》杂志6月号上。
研究人员根据身高体重指数（BMI）区分研究对象。他们发现，身高体重指数低于18．5的过瘦人群，罹患结肠癌的风险比身高体重指数在21．5至24．4之间的“理想体重”人群高33％，而身高体重指数高于27．4的过胖人群则比“理想体重”群体高46％。
身高体重指数是衡量人体健康状况的一个参考指数，其计算方法为体重（公斤）除以身高（米）的平方。
参与这项研究的新加坡国立大学研究人员说，他们对这一发现感到意外，仍在寻求生物学角度的合理解释。
研究人员在其论文中提出的一项解释是，过瘦人群罹患结肠癌的风险较高，可能与一种叫做“DNA氧化应激损伤”的轻微炎症有关，这种炎症破坏患者的免疫系统，让癌细胞得以增殖。
至于过胖人群易患结肠癌，一般认为是因为过胖者体内的胰岛素较多，可能削弱了阻止肿瘤生长的机体免疫力。（生物谷Bioon.com）
生物谷推荐原文出处：
Cancer DOI: 10.1002/cncr.25936
Body mass index and risk of colorectal cancer in chinese singaporeans?
Andrew O. Odegaard PhD, MPH1,*, Woon Puay Koh PhD2, Mimi C. Yu PhD3, Jian Min Yuan PhD, MD1,3Article first published online: 24 FEB 2011
Keywords:body mass index;obesity;underweight;Asians;colorectal cancer
Abstract
BACKGROUND:
The authors chose to examine the association between body mass index (BMI) and incident colorectal cancer across the spectrum of BMI, including underweight persons, because detailed prospective cohort data on this topic in Asians is scarce, as is data on underweight persons (BMI, <18.5 kg/m2) in any population.
METHODS:
Analysis of the Singapore Chinese Health Study included 51,251 men and women aged 45-74 years enrolled in 1993-1998 and followed through 2007. Incident cancer cases and deaths among cohort members were identified through record linkage, and 980 cases were identified. Cox regression models were used to investigate the association of baseline BMI with risk of incident colorectal cancer during a mean of 11.5 years of follow-up.
RESULTS:
A significant, U-shaped, quadratic association was observed between BMI and colon cancer risk, with increased risk in BMIs ≥27.5 and <18.5 kg/m2. The association was more pronounced in never smokers and most prominent when further limiting the sample to those free of diabetes and cases with longer than 5 years of follow-up. Localized cases had a more pronounced association in BMIs ≥27.5, whereas advanced cases had a more pronounced association in BMIs <18.5 kg/m2. No association was found in relation to rectal cancer risk. The association was also stronger among patients aged 65 years and older.
CONCLUSIONS:
BMI displays a U-shaped, quadratic association with colon cancer risk in this Chinese population in Southeast Asia. Cancer 2011;. ? 2011 American Cancer Society.
