Aims To assess the effect of local hyperthermia on the systemic absorption of mitomycin C (MMC) during intravesical chemotherapy for the treatment of super®cial transitional cell carcinoma of the bladder, and to establish the likely safety of this procedure. Methods Group 1 (n=12) received 20 mg intravesical MMC plus local hyperthermia, group 2 (n=13) 20 mg MMC alone, group 3 (n=16) 40 mg MMC plus local hyperthermia and group 4 (n=10) 40 mg MMC alone. Patients in groups 1, 2, and 4 underwent post-tumour resection adjuvant treatment, whereas those in group 3 still had tumour present and were treated to eradicate it. Intravesical instillation lasted 60 min, with the solution (50 ml) being replaced after the ®rst 30 min. Blood samples were taken before, and every 15 min during instillation. MMC concentrations in plasma and in urine were determined by h.p.l.c. Results The highest MMC plasma concentration (67.9 ng ml x1 ) occurred in a patient in group 3. This value was well below the threshold concentration (400 ng ml x1 ) for myelosuppression. Local hyperthermia associated with the intravesical chemotherapy enhanced plasma MMC concentrations at 30, 45 and 60 min compared with chemotherapy alone (Group 1 vs 2, Pj0.008). Systemic exposure to MMC was not signi®cantly increased by doubling the intravesical dose when intravesical chemotherapy alone was administered. Patients in group 3 displayed the highest degree of MMC absorption and the greatest variability in pharmacokinetics between patients. Conclusions Local hyperthermia enhances the systemic absorption of MMC during intravesical chemotherapy for bladder cancer. In the doses used, plasma MMC concentrations were always more than six times lower than those shown to cause toxicity.

According to these preliminary data, microwave induced hyperthermia combined with local intravesical chemotherapy seems to be a feasible, safe and promising approach for neoadjuvant and minimally invasive treatment of superficial bladder cancer.

Local hyperthermia of the prostate was used to treat 72 patients who had an indwelling catheter because of urinary retention caused by benign prostatic hypertrophy. One month after completion of treatment 50% of patients were able to dispense with the catheter and 1 year later 40% remained catheter-free. The best results were achieved in patients who underwent 6 to 10 treatment sessions in conjunction with cyproterone acetate 50 mg tid administered during the treatment period only.