RESUMO
The occurrence of second primary tumors after curative treatment or simultaneous multiple malignancies are current problem in head and neck cancer. The mutagen sensitivity is well known marker to predict patient proneness to develop the second tumor. The frequency and localization of spontaneous and mutagen induced chromatid breaks in peripheral blood lymphocytes (PBLs) in patients with multiple primary tumors (MPT) may help in defining regions involved in cancerogenesis process. The case control study using the bleomycin sensitivity assay (number of chromatid breaks per cell (b/c) was performed in 36 patients with MPT and two control groups: 52 patients with one malignancy and 47 healthy individuals. The differences between examined patients and control groups were estimated using U Mann-Whitney test. The b/c level in PBLs of patients with MPT ranged from 0.26 to 4.12 (mean 1.53) and was significantly higher (p<0.000006) both compared with patients with one malignancy (b/c ranged from 0.02 to 3.08; mean 0.74) and healthy controls (b/c ranged from 0.04 to 1.14; mean 0.41). An increase of b/c index was observed in almost all chromosomal arms. The majority of chromosomal locations with the increased proportion of breaks in the group of patients with multiple tumors were identified as regions where loci involved in DNA repair, cell cycle regulation suppressor genes and oncogenes were found. Statistically higher induced individual susceptibility in MPT patients compared with single tumor and healthy controls was confirmed. Comparable induced mean b/c was found in patients with two smoking-related cancers as well as with not smoking related tumors.