Allergy and other selected diseases and risk of colorectal cancer

It has been reported that allergy and other diseases may be related to colo rectal cancer risk. The aim of this study was to perform a systematic analy sis using information about medical histories specifically to see if there was any relation between allergies or other medical conditions and colorect al cancer risk. A multicentric case-control study was conducted in six Ital ian areas between 1992 and 1996 on 1225 incident cases of colon cancer, 728 cases of rectal cancer and 4154 controls comparable with cases according t o sex and age group, admitted for acute conditions to the same network of h ospitals where cases had been identified. Unconditional logistic regression models including terms for sex, age, study centre, years of education, bod y mass index, physical activity, smoking, history of colorectal cancer in f irst-degree relatives and energy intake were used to estimate the odds rati os (OR) of colon and rectal cancer according to history of allergy and othe r selected diseases. The OR for history of allergy was 0.88 (95% confidence interval, CI, 0.67-1.14) for colon and 0.64 (95% CI, 0.44-0.92) for rectal cancer, and the inverse association was stronger when allergy was diagnose d at age 35 years or more, or less than 10 years before the cancer diagnosi s. No clear pattern emerged in strata of age and sex. History of other sele cted diseases, including hypertension and cholelithiasis, was not related t o colon or rectal cancer risk, though there was a moderate increase in the risk of colon cancer (OR = 1.18, 95% CI, 0.66-2.14) in patients with a hist ory of intestinal polyps. This study lends support to the hypothesis that a llergic individuals may be at a lower risk of developing colorectal cancer. (C) 1999 Elsevier Science Ltd. All rights reserved.