[en] The types of defects and polymorphisms leading to hereditary susceptibility to cancer include proneness to increased DNA damage, recessive syndromes of faulty DNA repair and differentiation, as well as dominant mutations of cell cycle and control proliferation. The cancer susceptibility syndromes inherited in a dominant fashion are caused by mutations in tumor suppressor genes. These genes are recessive in relation to wild type alleles. In two syndromes of hereditary mutations in tumor suppressor genes (Rb and WT2), their expression 'in vivo' may be influenced by the sex of the transmitting parent, what points to modulation by imprinting. Genetic heterogeneity of the population in susceptibility to genotoxic agents is related to the individual variation in acceptable levels of exposure to agents and factors, such as products of incomplete combustion (PIC), UV ('xeroderma pigmentosum') and ionizing radiation ('ataxia telangiectasia'). DNA damage and adducts are considered to be indicative of genotoxic exposure and its effect as well as modulation of carcinogenic damage by genetic polymorphisms. Gene and protein polymorphisms are considered as markers of increased individual risk. Since environmental factors are considered to be able to control, the individual susceptibility to enhanced DNA damage and environmentally induced cancers could be counteracted by decreasing the levels of contamination or exposure. This explains the wide interest in markers of this individual sensitivity. Most of the postulated markers of sensitivity to PIV do not, however, prove to be generally applicable in that sense. Their prognostic value is limited either by low amplitude of the effect, or by their character specific either to the population or to the cancer type. The polymorphisms most relevant to cancers induced by PIC exposures may be those of inductibility of benzopyrene hydroxylase, and some other DNA polymorphisms concerning the CYP1A1 gene. (author). 24 refs, 1 fig., 3 tabs