Overweight and obese people in the Asia-Pacific region are at increased risk of certain types of cancer fatalities, investigators reported June 30 in the Lancet Oncology.
Although previous studies have demonstrated an association between body-mass index and cancer mortality, most of this research has been done in North American and European populations, Andrew Reenehan, Ph.D., of the University of Manchester, England, wrote in an editorial (Lancet Oncol. June 30 [doi:10.1016/S1470-2045(10)70148-0]) accompanying the study.
The study, which included more than 400,00 participants followed for a median of 4 years, found that the overall risk of dying from cancer (after excluding lung and upper aerodigestive tract cancers) was increased 21% in obese and 6% in overweight individuals, compared with those of normal weight (Lancet Oncol. June 30 [doi:10.1016/S1470-2045(10)70148-8]).
Furthermore, the risk of dying from cancer at the following sites was higher for the overweight and obese: cervix (hazard ratios 1.29 for overweight and 4.21 for obese), ovary (1.46, 2.62), rectum (1.44, 1.68), breast –in women 60 years of age and older (1.13, 1.63), colon (1.13, 1.50), and prostate (1.41, 1.45).
Of the 20 site specific cancers reviewed, only 8 were found to have positive statistically significant associations. In some instances, there proved to be inverse associations between high BMIs and cancer risk. In the case of lung cancer, the inverse association held even in overweight never-smokers.
The study’s lead author, Christine Parr, Ph.D., noted in an interview that obesity rates in Asia are still relatively low. She cautioned that for Asian policy makers, obesity should be a matter of major concern. “If obesity continues to rise throughout Asia, it could add to their cancer burden,” said Dr. Parr of the University of Oslo, Norway.
The findings did not reveal an increased risk of cancer death in obese and overweight Asians when compared to Western populations. Dr. Parr noted that past studies have found that Asians with high BMIs have been shown to be more prone to certain chronic diseases.
“There have been previous studies that have shown that Asians with the same BMIs as Westerners are at increased risk of diabetes and cardiovascular disease,” she said. “Then again, we’re not seeing the elevation in cancer risk. The mechanisms for why obesity leads to diabetes may not be the same as the mechanisms leading to cancer.”
The data considered in the study was derived from 39 different cohorts. The information, provided by the Asia Pacific Studies Collaboration, included men and women with a median age of 48.Of the 401,215 study participants, 77% were Asian. There were 4,872 cancer deaths—54% of which occurred in the Asian populations
The study defined normal weight as a body mass index (BMI) of 1.5-24.9 kg/m2, overweight as a BMI of 25-29.9 kg/m² and obesity is defined as a BMI greater than 30 kg/m2.
The study was funded by the National Health and Medical Research Council of Australia, the Health Research Council of New Zealand and Pfizer Inc. The study investigators declared no financial conflicts of interest.
Copyright (c) 2009 Elsevier Global Medical News. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.
据研究者们在6月30日的《柳叶刀-肿瘤学》(the Lancet Oncology)中报道的研究结果，亚太地区超重者和肥胖者某些类型的癌症死亡风险增加。
尽管先前有研究已证实体重指数(BMI)与癌症死亡率有关联，但该研究大多是在北美人群和欧洲人群中进行的，英格兰曼彻斯特大学的Andrew Reenehan博士在本研究的随刊编者按中写道。
这项研究共纳入逾40,000名受试者，中位随访时间为4年，其结果发现，与体重正常者相比，肥胖者死于癌症的总风险(排除肺部和上呼吸消化道癌症后)增加21%，而超重个体增加6%(Lancet Oncol. June 30 [doi:10.1016/S1470-2045(10)70148-8])。
此外，超重者和肥胖者死于以下部位癌症的风险亦较高：宫颈 (超重者和肥胖者的风险比值比分别为1.29和4.21)、卵巢(1.46，2.62)、直肠(1.44，1.68)、乳腺——60岁以上或更年长的妇女(1.13，1.63)、结肠(1.13，1.50)以及前列腺(1.41，1.45)。
在所分析的这20个癌症发病部位中，仅发现8个与BMI偏高有统计学上显著的正相关性。在某些情况下，BMI偏高与癌症风险之间存在负相关性。对于肺癌，即使是在超重的无吸烟史群体中仍然呈负相关性。
该研究的第一作者Christine Parr博士在一次受访中指出，亚组肥胖率仍相对较低。她警告说，对于亚洲政策制定者而言，应对肥胖给予极大关注。“若整个亚洲地区肥胖率持续增加，则会加重该地区的癌症负担，”挪威奥斯陆大学Parr博士说。
该研究将亚洲人与西方人进行比较时，并未显示肥胖和超重的亚洲人癌症死亡风险增加。Parr博士指出，以前的研究已发现，BMI偏高的亚洲人发生某些慢性疾病的倾向较大。
她说：“先前有研究表明，BMI与西方人相等的亚洲人发生糖尿病和心血管疾病的风险增加。我们目前还没有观察到癌症风险升高。肥胖引发糖尿病的机制可能不同于引发癌症的机制。”
本研究中分析的数据来自39个不同的队列。由亚太研究合作组织提供的资料中涵盖男性和女性，中位年龄为48岁。在401,215名受试者中有77%为亚洲人。有4,872例癌症死亡事件，其中54%发生于亚洲人群中。
该研究将正常体重定义为BMI介于1.5~24.9 kg/m2之间，超重定义为BMI介于25~29.9 kg/m²，肥胖定义为BMI> 30 kg/m2。
本研究由澳大利亚国家健康与医学研究委员会、新西兰健康研究委员会及辉瑞公司资助。研究者们无经济利益冲突的声明。
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