Colorectal cancer risk factors: a case-control study in Bangkok.

A case-control study for colorectal cancer risk factors was conducted in Bangkok, Thailand. A total of 279 incident cases of colorectal cancer were individually matched by sex, age and same hospital to 279 hospital controls with other cancers except gastrointestinal cancer. Each subject was interviewed with regard to bowel pattern information, family history, past history of illness and dietary information. The major findings were elevated risk for those with a history of bowel polyps (OR = 14.69, 95%CI = 2.01-301.46), parent's history of colon cancer (OR = 4.00, 95%CI = 1.39-12.43), anal abscess (OR = 3.78, 95%CI = 0.97-17.24), chronic colitis (OR = 3.61, 95%CI = 1.67-8.00), chronic hemorrhoid (OR = 3.13, 95%CI = 2.03-4.86) and the frequency of stools every three days or more (OR = 2.16, 95%CI = 1.17-4.01). The results also indicated an increased risk for dietary factors; bacon (OR = 12.49, 95%CI = 1.68-269.1) and butter (OR = 2.68, 95%CI = 1.29-5.68). There was a protective effect provided by banana (OR = 0.54, 95%CI = 0.37-0.79) and papaya (OR = 0.58, 95%CI = 0.40-0.84) for colorectal cancer. In unconditional logistic regression analysis, bacon showed the highest risk for colorectal cancer (OR = 8.82, 95%CI = 1.03-75.57), instead of bowel polyps (OR = 4.50, 95%CI = 0.48-42.59). The data suggest that nitrite-treated meat increases colorectal cancer risk while dietary fiber decreases colorectal cancer risk.