Rationale for intravesical chemotherapy in the treatment and prophylaxis of superficial transitional cell carcinoma.

1. A thorough evaluation of the urinary tract is an integral part of the initial management of a patient with transitional cell carcinoma. The site of all urothelial abnormalities must be determined and adequate histologic material obtained and reviewed. The urothelium not involved by obvious tumor should also be evaluated by either cytology or mucosal biopsies. All patients with high grade tumor should have a biopsy from the prostatic urethra. 2. The clinician should determine the risk of progression by evaluating the tumor grade, stage, and the presence or absence of carcinoma in situ. 3. The likelihood of a recurrence following endoscopic resection of a superficial bladder tumor ranges from 20% for a solitary low grade tumor to over 90% for a patient with multifocal high grade cancer. 4. The reasons for the high incidence of a subsequent tumor include new occurrences related to the continued contact of carcinogens with the susceptible urothelium, failure to completely resect all tumor, and possibly the implantation of tumor cells on the altered urothelial surface following endoscopic resection. 5. Intravesical instillation of antineoplastic agents is capable of reducing the incidence of a subsequent tumor when used for prophylaxis. These agents are also capable of eradicating residual tumor. 6. The clinician should determine whether intravesical therapy is being used for treatment or prophylaxis. 7. Thiotepa is a relatively inexpensive and safe intravesical chemotherapeutic agent which, when used for treatment of existing tumor, will provide a complete response rate of from 35 to 45%. There is a suggestion that it is more effective in low grade than high grade tumors. Prospective randomized trials indicate that patients receiving Thiotepa are less likely to develop a subsequent tumor in a given period of time than patients who do not receive intravesical therapy. 8. Mitomycin-C will provide a complete response rate in high risk patients from 35 to 50% when used for treatment of existing tumor. Approximately 15% of such patients will progress to muscle invasion if followed for approximately three years. There are few randomized trials using Mitomycin-C to determine its efficacy for prophylaxis. 9. BCG has been used for treatment and prophylaxis of superficial bladder cancer. It is relatively inexpensive. The side effects vary with the strain. Several strains have been used but they have not been compared in randomized trials. When used for treatment, the complete response rate ranges from 50 to 65%.(ABSTRACT TRUNCATED AT 400 WORDS)