Effect of pair-feeding of carcinogen on the incidence of bladder tumors in hamsters. Role of indole, age, and sex.

The role of indole in 2-acetylaminofluorene (AAF) bladder tumorigenesis was critically evaluated in hamsters. To avoid the influence of a nutritional factor on the tumor incidence, the animals were pair-fed for 8, 10, and 12 months. Addition of indole to the AAF diet resulted in a higher incidence of bladder tumors in both males and females (P less than 0.05, P less than 0.05). Indole definitely increased the bladder tumor incidence at 8 months (P less than 0.05). Also significantly different was the tumor incidence between males and females irrespective of the diet administered (P less than 0.05). Indole did not alter the urinary output of N-hydroxy-2-acetylaminofluorene (N-OH-AAF) in males.