Despite effective treatment of existing tumors, patients with bladder cancer 
remain at risk of developing new tumors. Effective immunotherapy may lower that 
risk. To test this hypothesis, mice that had survived transitional cell 
carcinoma (MBT2) transplantation with the aid of bacillus Calmette-Guerin 
immunotherapy were randomized and tested for long term protective immunity 
against bladder carcinoma. Fifty-one tumor-free mice that had survived tumor 
challenge 10 to 15 months previously were randomized into 3 groups to receive 
intradermal tumor .noculation and intraperitoneal levamisole, intralesional Tice 
strain bacillus Calmette-Guerin, or intralesional saline. Fifteen previously 
unchallenged animals also received tumor and intralesional saline. All 3 groups 
of survivors had less tumor growth (p less than 0.01) than nonsurviving 
controls. Even among survivors, additional bacillus Calmette-Guerin 
immunization, but not levamisole treatment, significantly inhibited tumor growth 
(p less than 0.01). A 2nd experiment compared 22 nonimmune mice, 21 mice 
preimmunized intravenously with 300 micrograms of bacillus Calmette-Guerin cell 
walls, and 18 mice that had survived MBT2 by 8 months after live bacillus 
Calmette-Guerin treatment. Nonimmune and survivor groups were randomly 
subdivided into saline or treatment groups. Cell wall-preimmunized mice were 
divided into matching groups according to footpad response to purified protein 
derivative. The cell-wall preimmunized and nonimmune mice received the 
immunostimulant P3+Re-glycolipid or the carrier solution alone. The group of 
survivors received either intralesional saline or live bacillus Calmette-Guerin. 
Both bacillus Calmette-Guerin and saline-treated groups had significantly less 
tumor growth (p less than 0.001) than nonsurviving controls. Animals treated 
with P3-Re-glycolipid (with or without preimmunization with cell wall) did not 
differ from nonsurviving control. Footpad response to purified protein 
derivative did not correlate with tumor growth in these mice. Our results 
suggest that intralesional bacillus Calmette-Guerin immunotherapy can afford 
long term protection from transplanted bladder cancer, and that live bacillus 
Calmette-Guerin is superior to levamisole and P3 + Re-glycolipid + bacillus 
Calmette-Guerin cell walls in the treatment of bladder cancer.