Obesity, weight gain and risk of colon adenomas in Japanese men

Obesity has been related to increased risk of colon cancer or adenomas, but the epidemiologic findings are not entirely consistent. We examined the re lation of not only body mass index (BMI) but also waist-to-hip ratio (WHR) and weight gain to colon adenoma risk in men who received a preretirement h ealth examination at the Japan Self Defense Forces (SDF) Fukuoka and Kumamo to Hospitals during the period from 1995 to 1996, In the series of 803 men at age 47-55 years, 189 cases of colon adenomas and 226 controls with norma l total colonoscopy were identified. Weight at 10 years before was ascertai ned by referring to the recorded data. After allowance for hospital, rank i n the SDF, smoking and alcohol use, weight gain over the past 10 years was significantly associated with increased risk of colon adenomas (odds ratio for greater than or equal to 6 kg versus less than or equal to-2 kg = 2.2; 95% confidence interval 1.0-4.8), High BMI and high WHR were each associate d with increased risk, but only WHR was related to the risk independently o f weight gain. In particular, weight gain accompanied with a high WHR was a ssociated with a significant increase in the risk. Men with high physical a ctivity tended to have lower risk. Associations with obesity-related variab les and physical activity were not materially differential as regards the L ocation and size of adenoma, The findings indicate that weight gain in midd le age leading to abdominal obesity increases the risk of colon adenomas, a nd consequently of colon cancer.