POPULATION-GENETICS OF COLONIC-CANCER

Background. There are several well known but rare syndromes of inherited colonic cancer. Genetic epidemiologic studies also have demonstrated that relatives of individuals with colonic cancer in general exhibit an excess risk for this malignancy. Methods. This report reviews the literature pertinent to genetic and familial risk for colonic cancer with emphasis on the recent work that suggests that inherited susceptibility to colonic neoplasms is common. Results. The adenomatous polyposis syndromes are rare inherited colonic cancer conditions caused by a mutant gene which recently has been characterized. Hereditary nonpolyposis colorectal cancer is likewise inherited and may account for up to 5% of cases. The molecular genetics of this disease remain to be clarified. The majority of colonic cancer cases are considered sporadic but are known to often cluster in families. Recent work suggests that inherited susceptibility may be the basis of this familial occurrence. Screening strategies based on inherited and familial risk are suggested. Conclusions. Knowledge of the familial and inherited risk for colonic cancer is leading to a better understanding of this disease and is suggesting more directed preventive strategies.