Predictive value of tumor invasion patterns on intravesical bacillus Calmette-Guérin response for stage T1 high-grade non-muscle-invasive bladder cancer.

Purpose: Parameters predicting intravesical bacillus Calmette-Guerin (BCG) treatment response in non-muscle-invasive bladder cancer (NMIBC) are limited. This study investigated the effectiveness of tumor invasion patterns in predicting intravesical BCG treatment response, which are known to have prognostic value for NMIBC.

Materials and methods: Data of 167 primary, stage T1 high-grade NMIBC patients evaluated retrospectively. All transurethral resection samples were re-evaluated for confirmation of pathological variables and determination of invasion patterns. Binary logistic regression analysis applied to obtain determinants of BCG response. Kaplan-Meier curves and log-rank test used to assess relationship between variables and time to recurrence and time to progression.

Results: Tumor invasion pattern was nodular in 83 (49.7%), trabecular in 20 (12.0%) and infiltrative in 64 patients (38.3%). Multivariate analysis revealed multifocality (p=0.001), trabecular invasion (p=0.001) and infiltrative invasion (p=0.001) were independent predictors of poor BCG response. Log-rank test determined infiltrative invasion has higher impact on time to recurrence (p<0.001) and nodular invasion has significantly lower risk for time to progression (p=0.013), during the median follow-up period of 15 months.

Conclusions: Invasion patterns are significantly correlated with BCG response. Assessment of this easily applicable parameter can differ patients who may benefit from BCG treatment and can be used as a prognostic indicator.