RESUMO
The aim of this research was to determine the occurrence of epidermoid carcinoma of the esophagus induced by diethylnitrosamine (DEN) in Wistar rats. DEN was administered (250-300 g) in drinking water (10 mg/kg body weight) to four groups of rats for 72 h/week, for a duration of 90, 120, 150, or 200 days (groups T90, T120, T150, and T200). Ten animals whose drinking water did not contain DEN constituted the control group. All rats were sacrificed and their esophaguses studied macro- and microscopically. The control group did not exhibit either carcinomas or preneoplasic lesions. The T120 and T200 groups presented, respectively, 47 and 58 in situ carcinomas; 1 and 20 submucosal carcinomas (P < 0.05); 4 and 17 microinvasive carcinomas (P < 0.05); 4 and 11 advanced carcinomas (P < 0.05); and 1 and 1 cases of benign hyperplasia. Pulmonary and liver carcinomas were also found in the T200 group. The majority of advanced macroscopic lesions in the T200 group were polypoid, exophytic, and not microscopically invasive in the esophageal wall. This research confirms the effectiveness of the DEN in bringing about carcinogenesis in the Wistar rat esophagus and also shows that the lesions are dosage dependent.