Production of urinary tract tumors by co-administration of uracil and N-[4-(5-nitro-2-furyl)-2-thiazolyl]-formamide in F344 rats.

Co-administration of uracil and N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT) to weanling female Fischer rats produced uracil stones in the bladder and significantly reduced the incidence of bladder tumors. Contrary to bladder tumors, the incidence of renal pelvic and ureteric tumors was increased by this regimen. Feeding of uracil alone produced bladder tumors, in addition to the hyperplasia of renal pelvis, ureter and bladder. The mechanism of uracil's effect on FANFT carcinogenesis is not known.