An overview of intravesical therapy for superficial bladder tumors
Urinary Bladder Neoplasms
Bladder cancer is the third most prevalent malignant disease among male patients and the tenth among female patients in the United States. More than 45,000 new cases are recorded annually, of which 75 to 80 per cent present as superficial tumors (categories Ta, Tis and T1). Recurrences are more common than not, making bladder cancer probably the most common epithelial tumor diagnosis in man. Recurrence rates vary from 30 per cent with a solitary papillary tumor to more than 90 per cent in some cases of multiple tumors. Most tumors recur within 6 to 12 months at the same low stage and grade but 5 to 30 per cent of all cases and up to 80 per cent of selected patients exhibit progression of disease. The high probability of recurrence coupled with the unpredictable and more ominous possibility of progression have fostered widespread use of intravesical therapy to control existing tumors (therapy) and to reduce tumor recurrences (prophylaxis). The rationale for intravesical therapy is that high concentrations of drug may contact tumor-bearing mucosa for prolonged periods, the likelihood of tumor implantation after resection may be reduced by destroying viable cancer cells, a cytotoxic effect on residual carcinoma may be provided, a salutary effect on precursor mucosal lesions may occur, there is minimal toxicity owing to limited systemic absorption and progression of disease requiring more intense local therapy, cystectomy or systemic chemotherapy may be delayed or prevented. How effective is intravesical therapy for superficial bladder tumors? We must look realistically at experiences to date from 2 perspectives: 1) patient care and what the practicing urologist should be doing, and 2) clinical research, and the conceptual thrust and design of future studies. We review current data regarding intravesical therapy and the methodology upon which such data are based, and translate this information into practical guidelines for urologists who manage individual patients. To fulfill this aim we drew upon published results from selected clinical trials that provide pertinent information for guiding therapeutic choices.