RISK OF COLON-CANCER ASSOCIATED WITH A FAMILY HISTORY OF CANCER OR COLORECTAL POLYPS - THE DIET, ACTIVITY, AND REPRODUCTION IN COLON-CANCERSTUDY

The Diet, Activity, and Reproduction in Colon Cancer (DARCC) study is a large, multi-center case-control study of colon cancer. We examined family histories of cancer among first-degree relatives obtained by co mputer-assisted in-person interviews from the DARCC to study the impac t of family histories of several cancers and colorectal polyps on colo n cancer risk. We examined familial cancer risks both by treating a fa mily history of polyps or cancer as a covariate in a logistic regressi on model, and by comparing cancer or polyp incidence among relatives o f cases to incidence among relatives of controls in a proportional haz ards model. There were few differences between the odds ratios (OR) or confidence intervals (CI) generated from logistic regression models a nd the hazard rate ratios (HRR) generated from the proportional hazard s models. Overall, the OR of colon cancer among subjects with a family history of colorectal cancer was 1.77. There were only minor differen ces in risk by sex, age and subsite, A family history of colorectal po lyps also increased risk by about the same amount as a family history of colorectal cancer. The increased risk associated with a family hist ory of polyps did not appear to decrease with age. (C) 1998 Wiley-Liss , Inc.