Bacillus Calmette-Guerin immunotherapy has been found by a number of 
investigators to be effective in the treatment and prevention of superficial 
bladder cancer. While the optimal protocol for bacillus Calmette-Guerin remains 
to be determined, experience with 92 randomized and 30 nonrandomized (high risk) 
patients followed for up to 5 years provides information that may improve future 
protocols. Side effects of bacillus Calmette-Guerin are observed to increase 
with increasing frequency and duration of treatment. The protection from tumor 
recurrence has persisted: only 6 of 30 patients (20 per cent) treated with 
bacillus Calmette-Guerin have had recurrent tumor compared to 14 of 27 controls 
(52 per cent, p equals 0.008, chi-square test), and mean time to recurrence 
increased from 24 to 48 months (p less than 0.005, Savage). Skin test reactivity 
to purified protein derivative is particularly useful in predicting response to 
bacillus Calmette-Guerin immunotherapy. Currently, 60 patients have been 
randomized to receive bacillus Calmette-Guerin immunotherapy and only 1 of 22 
patients (4.5 per cent) in whom the purified protein derivative skin test 
results converted from negative to positive has had recurrent tumor, compared to 
12 recurrences (32 per cent) in patients whose skin tests were positive before 
treatment or failed to convert following treatment (p equals 0.014, chi-square). 
Seven recurrences (33 per cent) developed in 21 patients whose skin tests 
remained negative (p equals 0.015) and 5 recurrences (29 per cent) developed in 
17 patients whose tests previously were positive (p equals 0.068, Fisher's test, 
not significant). The benefit of percutaneous bacillus Calmette-Guerin is 
suggested by the observations that the recurrence rate in patients treated with 
intravesical bacillus Calmette-Guerin alone is 40 per cent, and all 7 patients 
whose purified protein derivative skin tests were negative continued to have 
negative results when percutaneous bacillus Calmette-Guerin was omitted (p 
equals 0.003). Among high risk patients a marked decrease in or complete 
prevention of recurrent tumor was observed in 82 per cent of 22 patients treated 
previously with chemotherapy and 11 of 14 (78 per cent) with carcinoma in situ 
have had a complete response.