Mutual neoplastic promotion by instillation of mitomycin C and cauterization on rat bladder urothelium.

The authors studied the effect of bladder instillation of mitomycin C (MMC), a potential carcinogen, on the duration and severity of the hyperplasia induced by transurethral fulguration. This experimental system may simulate closely the intravesical chemoprophylaxis of MMC after transurethral resection of bladder cancer. Physiologic saline or MMC was instilled into the rat bladder once on the day of, or 3 or 7 days after cauterization. In all groups instilled with physiologic saline the changes were reversed by day 14. On the other hand, five of nine MMC-instilled rats developed papillary lesions, and three of these had mild dysplastic epithelium on day 84. Under the scanning electron microscope, the animals of these groups showed pleomorphic microvilli on the luminal surface of the regenerative cells on days 10 and 14 after cauterization. These results may indicate the mutual neoplastic promotion by instillation of MMC and cauterization to a certain extent.