Sarcopenia Weakens the Benefit of Bacillus Calmette-Guérin in Non-Muscle-Invasive Bladder Cancer: A Computed Tomography-Based Cohort Study.

OBJECTIVES

Non-muscle-invasive bladder cancer (NMIBC) commonly recurs despite intravesical Bacillus Calmette-Guérin (BCG) therapy. Host factors that modify the effectiveness of BCG have not been completely defined. We evaluated whether sarcopenia is associated with outcomes after BCG in Japanese patients.

METHODS

We conducted a retrospective single-center cohort study (2010-2023) including high-grade (HG) NMIBC patients treated with BCG (n = 139) and those not receiving BCG (n = 100). Sarcopenia was defined a priori using sex- and BMI-specific skeletal muscle index (SMI) and psoas muscle index (PMI) cutoffs derived from baseline L3 computed tomography and validated in Asian adults. The endpoints were intravesical recurrence-free survival (IVRFS), high-grade recurrence-free survival (HGRFS), progression-free survival (PFS), and overall survival (OS). Feature selection used LASSO-Cox with cross-validation; performance was assessed using time-dependent ROC. Within the BCG cohort, we conducted a 1:1 propensity score matching.

RESULTS

In the BCG cohort, 93/139 (66.9%) and 69/139 (49.6%) patients were classified as sarcopenic according to SMI and PMI, respectively. One- and two-year apparent AUCs for intravesical recurrence were 0.75 and 0.79 (validation AUCs 0.68 and 0.71). Kaplan-Meier analyses revealed no differences in outcomes by sarcopenia in the non-BCG cohort but worse outcomes across endpoints in the BCG cohort. After matching, SMI-based sarcopenia was associated with shorter IVRFS, whereas PMI-based sarcopenia was associated with shorter IVRFS, HGRFS, PFS, and OS.

CONCLUSIONS

Patients with sarcopenia were less likely to benefit from BCG. The incorporation of computed tomography-based muscle indices into pre-BCG decision-making may improve risk stratification and supportive care.