DNA repair proficiency: a potential marker for identification of high risk members in breast cancer families.

Breast cancer is the single largest cancer and causes the high rate of cancer mortality among women. A positive family history of breast cancer is recognized as one of the major risk factors for this disease. The present study evaluates bleomycin (BLM)-induced chromosome sensitivity analysis in breast cancer families which provides indirectly a measure of the DNA repair defect of each person. BLM sensitivity assay on cultured lymphocytes of 36 familial breast cancer patients, their 85 first or second degree female relatives, 36 sporadic breast cancer patients and 40 age- and sex-matched controls (without any family history of cancer) were carried out to measure interindividual variation in their DNA repair capacity through mutagen-induced chromosome sensitivity analysis. Fifty percent of familial breast cancer patients and seven unaffected relatives showed hypersensitivity. Compared to hyposensitive relatives these seven subjects may be considered as high risk individuals.

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 suitable model for illustrating multistep tumor development. Bleomycin induced chromosome sensitivity studies were done in 7 colorectal cancer families consisting of 12 colorectal cancer patients and their 34 first degree relatives and 12 sporadic colorectal patients for comparison and identification of high risk family members with genetic instability. 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 present) individuals. The study is being continued in more number of familial colorectal cancer patients and their relatives to arrive at definite conclusions.