The advantage of BCG immunotherapy over intravesical chemotherapy in superficial 
bladder cancer has been most apparent in patients with carcinoma in situ (CIS), 
where complete response is increased from 50% to more than 70% and the 
proportion of patients remaining disease free for 5 years is increased from 20% 
to 40%. Similar advantages have been reported using suboptimal BCG treatment 
schedules in patients with recurrent stage Ta, T1 tumours. BCG provides long 
term protection from tumour recurrence and, unlike chemotherapy, reduces tumour 
progression. The observed relative increased sensitivity of CIS to BCG and the 
occasional failure of BCG to demonstrate significant superiority over mitomycin 
C in the prevention of tumour appear to be related to the use of suboptimal BCG 
treatment schedules. With maintenance BCG using 3 weekly instillations at 6 
month intervals, patients with papillary tumours fare even better than patients 
with CIS, and tumour progressio is even further reduceld. Chemotherapy is 
appropriate for patients who are at very low risk of tumour progression and 
those who fail to respond to BCG, but overall the results of BCG immunotherapy 
are superior for patients with either CIS or Ta, T1 transitional cell carcinoma.