The effect of intravesical thio-tepa on normal and tumor urothelium

Intravesical thio-tepa instillations for 55 patients with superficial transitional cell carcinoma were evaluated prospectively in the treatment of residual disease (therapeutic) and the prevention of recurrence (prophylactic). The over-all response rate to therapeutic thio-tepa was 56 per cent, with toxicity observed in 26 per cent of the cases. Patients with microscopic residual tumor showed better response and less toxicity than those with gross residual tumor. Prophylactic thio-tepa had no effect in lowering recurrence rates. Examination of pre-treatment and post-treatment biopsies showed no worsening of atypia and no correlation between improvement in atypia and gross tumor response. A charcteristic post-treatment thio-tepa effect was observed in non-tumorous urothelium but not in tumor biopsies. The differentiation of such thio-tepa effect cells from pre-malignant atypical cells is discussed.