[Heredity and cancers]

Cancer is a disease at the DNA level, originating from mutations of genes involved in the regulation of cell proliferation and differentiation: oncogenes and tumor suppressor genes. Only a few proportion of tumors, resulting mainly from germ-line anti-oncogene inactivation, arise in the frame of inherited cancer syndromes with mendelian mode of transmission. There may also be a much larger number of cases who are less strongly predisposed, without evident familial clustering. Genes involved in DNA repair process and in metabolism of carcinogenesis may be responsible. Study of genetic predisposition to cancer have important implications for screening individuals at high-risk in families.