Biological behavior of N-[4-(5-nitro-2-furyl)-2-thiazolyl]-formamide induced carcinoma of the transitional epithelium in the rat.

30 female Wistar rats weighing between 70 and 90 g were fed for 8 months with 0,188% N-[4-(5-nitro-2-furyl)-2-thiazolyl] Formamide (FANFT). After this period a papillary tumor of the urinary bladder was demonstrable in each animal. Histological examination always revealed a transitional cell carcinoma with prevailing medium tumor stages; no distant metastases were found. The grade of malignancy was classified as medium and high. No significant statistical relationship could be ascertained between tumor stage and grade or between grade and weight, but a correlation was established between tumor stage and weight. After 12 months, 36/60 kidneys were found to be normal, whereas in 20/60 dysplasias and in 2/60 transitional cell carcinomas of the renal pelvis were observed; secondary hydronephrosis due to bladder tumors occured 4 times. Other organ changes were not noticeable.