[Genetic factors in carcinogenesis].

A genetically high risk group for cancer may consist of persons with the following characteristics. Deficient or reduced capacity for repair of DNA damage, mostly occurring in patients with cancer-prone hereditary diseases, and possibly heterozygotes with the autosomal recessive genes of these diseases. The presence of chromosomal diseases with high incidence of cancer (e. g. Down's syndrome). The presence of autosomal dominantly inherited cancer-prone diseases. Efficient capacities for metabolic activation of potential carcinogens or reduced capacities for decomposition of carcinogens. Although the number of persons with a hereditary high risk may be small, heterozygotes of cancer-prone hereditary disease genes may account for a few percent of the general population. Relative risk, however, may be much lower in these heterozygotes than in patients, judging from the epidemiological data for ataxia telangiectasia and xeroderma pigmentosum. Correlation between cancer-proneness in these genetically high-risk groups for cancer and mutability in the cells originating from these persons has not been clearly demonstrated. Family studies and twin studies may provide further aspects for consideration of genetic factors.