Abstract
Despite its marked effectiveness in the prevention of tumor recurrences, a great deal of information on the mode of action of Bacillus Calmette-Guérin (BCG) as an antitumor therapy modality is still lacking. In this prospective study, by performing lymphocyte subset analysis and quantitative assessment of delayed hypersensitivity skin reactions before transurethral resection of the detected tumor and 3-6 months after intravesical BCG administration in 23 patients with superficial bladder carcinoma, we tried to demonstrate the immunostimulatory effect of BCG therapy. We had 4 recurrences at 6 months’ follow-up. Evaluation of lymphocyte subset analysis readings in our group revealed a statistically significant difference (p < 0.05) in CD4+/CD8+ ratio between baseline values and that obtained following BCG administration at 3 and 6 months. However, there was no statistically significant increase of this value in 4 patients who had tumor recurrences. Evaluation of delayed hypersensitivity skin test score results revealed a statistically significant increase in the whole group at 3 months of follow-up (p < 0.05) but the same evaluation at 6 months of follow-up showed no statistically significant difference with respect to this evaluation. Again, no statistically significant difference was found in 4 patients who had tumor recurrences. These results support the idea that BCG-associated antitumor activity is an immune-mediated reaction and the assessment of T-lymphocyte subsets together with quantitative avaluation of delayed hypersensitivity skin reactions would give us a definite idea about the immunotherapeutic effects of BCG in such patients.