RESUMO
The model of hamster cheek pouch carcinogenesis closely mimics the development of human oral cancer. The study of the interaction between chemical carcinogens and radiation in the process of oral carcinogenesis is of interest given that the oral cavity is frequently exposed to chemical carcinogens such as alcohol and tobacco and is the route of entry of therapeutic radiation. In this context, markers of incipient alterations associated to a process of malignant transformation would contribute to early diagnosis and follow-up. The aim of the present study was to assess the early changes produced by carcinogenic agents applied separately or combined in a two-stage carcinogenesis protocol in hamster cheek pouch. The cheek pouch of the hamsters was treated with a single dose of radiation (20 Gy) or 7,12-dimethylbenz(a)anthracene (DMBA) as initiating agents and 12-O-tetradecanoylphorbol-13-acetate (TPA) as a promoting agent for 1 or 2 weeks. The end-points chosen to identify early alterations were hyperplastic foci and silver-stained nucleolar organizer regions (Ag NOR). The data show that both markers are useful in the detection of early alterations compatible with a process of malignant transformation.