Does switching Bacillus Calmette-Guerin strains during maintenance therapy affect the outcome in non-muscle invasive bladder cancer?

ABSTRACT Objective To compare the patients who have recieved one type of BCG strain during maintenance therapy with patients treated with multiple BCG strains. Material and Methods We reviewed 279 patients treated with BCG between January 2012 and May 2019, retrospectively. The primary endpoints of the study were recurrence-free survival (RFS) and progression-free survival (PFS) rates among patients receiving same BCG strain (Group-1) and multiple BCG strains (Group-2). Matching analysis was performed to balance the groups. The Kaplan-Meier method was used for estimating RFS and PFS. The difference between the two groups in terms of adverse effects was evaluated using the chi-square test. Results A total of 225 (80.6 %) patients were treated with single BCG strain, and 54 (19.4 %) were treated with multiple BCG strains. Overall, recurrence and progression was observed in 86 (30.8%) and 38 (13.6%) patients, respectively. There was no significant difference between the two groups in terms of recurrence-free survival and progression-free survival on both without matching and with propensity score match analysis (log rank; p=0.760 and p=0.559, p=0.533 and p=0.509 for non-match and matched analysis respectively). Most of the patients in both groups experienced BCG therapy related side effects, but there was no statistically significant difference between groups (p=0.235/0.833). Conclusions Switching the BCG strain because of unavailability of the induction strain does not decrease the effectiveness of the treatment. When it is not possible to reach the starting BCG strain, treatment can be safely continued with any available strain.