THE CYTOGENETIC IDENTIFICATION OF HIGH-RISK MEMBERS IN COLORECTAL-CANCER FAMILIES

Family history of colorectal cancer is recognized as a risk factor for the disease and the development of colorectal cancer represents a sui table model for illustrating multistep tumor development. Bleomycin in duced chromosome sensitivity studies were done in 7 colorectal cancer families consisting of 12 colorectal cancer patients and their 34 firs t degree relatives and 12 sporadic colorectal patients for comparison and identification of high risk family members with genetic instabilit y. All patients and 4 unaffected relatives showed increased bleomycin sensitivity, which might be due to defective DNA repair system. These four relatives may be classified as high risk (without cancer at prese nt) individuals. The study is being continued in more number of famili al colorectal cancer patients and their relatives to arrive at definit e conclusions.