A Cohort Study on the Association of Impaired Glucose Tolerance with Cancer Risk in 2 Towns of Hokkaido

目的：通过一项队列研究，我们评估了葡萄糖耐量降低（RGT）与癌症发生之间的关系。方法：于1977年和1978年分别从日本北海道的天野镇和小别镇随机抽取年龄在40 ~ 64岁之间的908名男性和1081名女性作为研究对象。对研究对象进行血清总蛋白、白蛋白、尿酸、总胆固醇、β-脂蛋白、甘油三酯测定及50g口服葡萄糖耐量试验。随访至2002年底，对2001年7月参加大规模筛查项目的590人（30.0%）进行访谈，了解其既往病史。采用Cox比例风险模型估计风险比（hr）及其95%置信区间（95% ci）。在随访期间，145名受试者（94名男性和51名女性）被报告患有癌症。我们分析的数据不包括任何自基线调查以来观察时间少于5年的人。结果：男性受试者口服50g葡萄糖后120分钟，年龄调整后的患癌HR在血浆葡萄糖的四分位数上显著增加（p为趋势，p=0.039）。即使在调整吸烟和饮酒习惯以及年龄之后，这一结果也没有实质性的改变（p代表趋势，p=0.044）。结论：RGT与癌症风险增加的关系可能是病原学的，其生物学机制可能有多种解释。如果是这样，就表明防止葡萄糖耐量受损或降低可能对降低癌症风险很重要。需要进一步的研究来评估与GTR相关的其他可能因素的作用，如能量摄入增加和体力活动减少。

Purpose : By means of a cohort study, we evaluated the association between reduced glucose tolerance (RGT) and the occurrence of cancer.Methods : A thousand nine hundred and eighty nine persons (908 males and 1,081 females) aged from 40 to 64 years from towns of Tanno and Sohbetsu in Hokkaido, Japan were randomly selected as the subjects of this study in 1977 and 1978, respectively. Measurements of total protein, albumin, uric acid, total cholesterol, β-lipoprotein, and trigliceride in serum as well as 50g oral glucose tolerance test were performed for the study subjects. They were followed-up until the end of 2002, and 590 persons (30.0%) among the study subjects, who attended mass-screening programs in July of 2001, were interviewed to obtain their past history. Hazard ratios (HRs) and their 95% confidence intervals (95%CIs) were estimated by Cox's proportional hazard model. In the follow-up period, 145 subjects (94 males and 51 females) were reported to have cancer. We analyzed the data not including any who had been observed for less than 5 years since the baseline survey.Results : As a result, the age-adjusted HR for having cancer was significantly increased over quartiles of plasma glucose at 120 minutes after a 50g oral glucose load in the male subjects (p for trend, p=0.039). This result was not substantially modified even after adjusting for habits of smoking and drinking in addition to age (p for trend, p=0.044).Conclusion : The relationship between RGT and increased risk of cancer may be etiological with several possible explanations for the biological mechanism. If so, it has been suggested that protection from impaired or reduced glucose tolerance may be important for reducing the risk of cancer. Further studies are necessary to evaluate the role of other possible factors working in conjunction with GTR such as increased energy intake and decreased physical activities.