Objective: To assess the clinical outcomes of highest-risk non-muscle-invasive bladder cancer patients treated with intravesical bacillus Calmette-Guérin.

Methods: The medical charts of patients with non-muscle-invasive bladder cancer treated with intravesical bacillus Calmette-Guérin between 2000 and 2018 at a single institution were retrospectively reviewed. Patients were stratified into three groups (intermediate-, high- and highest-risk groups) according to the risk classification of the updated Japanese Urological Association guidelines 2019. Among the three groups, the intravesical recurrence-free survival and progression-free survival were estimated and compared, respectively. Furthermore, the different types of risk factors in the highest-risk group were analyzed.

Results: Of the 165 patients, 49 (30%) patients had intravesical recurrence and 23 (14%) patients showed progression to muscle-invasive disease during a median follow-up period of 53 months. Significant differences were not noted in the recurrence-free survival and progression-free survival among the three groups. Multivariable survival analysis of 74 patients in the highest-risk group showed that carcinoma in situ in the prostatic urethra was a significant predictor associated with recurrence (hazard ratio 3.20, P = 0.026) and progression (hazard ratio 4.36, P = 0.013).

Conclusions: Intravesical bacillus Calmette-Guérin can control highest-risk non-muscle-invasive bladder cancer in most patients. Our findings might aid in decision-making regarding the treatment of this subset of patients who require intensive treatment, such as intravesical therapy with bacillus Calmette-Guérin and radical cystectomy.