COMBINED EFFECT OF CARCINOGENIC N-NITROSO DIMETHYLAMINE PRECURSORS AND FRACTIONED GAMMA-IRRADIATION ON TUMOR-DEVELOPMENT IN RATS

The influence of combined action of N-nitrosodimethylamine (NDMA) and fractioned gamma-irradiation on tumor development in rats was investig ated, Both the tumor frequency and tumor plurality coefficient Rave be en studied for two types of treatment: precursors of NDMA (amidopyrine and/or sodium nitrite (SN)) alone and the combination ''precursors pl us radiation''. Tumor frequency decreased by about 11% after combinati on of gamma-irradiation and precursors in comparison with precursors a lone. Nevertheless, treatment with SN and gamma-irradiation did not ch ange tumor frequency in comparison with SN alone. irradiation of rats treated with precursors led to an increased tumor plurality coefficien t.