Sarcopenia Predicts Disease Progression in Patients with T1 High-grade Non–muscle-invasive Bladder Cancer Treated with Adjuvant Intravesical Bacillus Calmette-Guérin: Implications for Decision-making?

Background: Skeletal muscle loss (sarcopenia) has been linked to cancer cachexia and can predict survival in several tumors, including advanced genitourinary malignancies. Objective: To investigate the predictive and prognostic role of sarcopenia in patients with T1 high grade (HG) non-muscle invasive bladder cancer (NMIBC) treated with adjuvant intravesical Bacillus Calmette-Guerin (BCG). Design, setting, and participants: Oncological outcomes were evaluated for 185 patients with T1 HG NMIBC treated with BCG at two European referral centers. Sarcopenia, identified from computed tomography scans performed within 2 mo after surgery, was defined as a skeletal muscle index of <39 cm2/m2 for women and <55 cm2/m2 for men. Outcome measurements and statistical analysis: The main endpoint was the association between sarcopenia and disease recurrence and progression. Kaplan-Meier curves and multivariable Cox models were built, and the clinical value of any association was assessed using Harrell's C index and decision curve analysis (DCA). Results and limitations: Sarcopenia was present in 130 patients (70%). On multivariable Cox regression analyses that accounted for the effect of standard clinicopathological prognosticators, sarcopenia was independently associated with disease progression (hazard ratio 3.41; p = 0.02). Addition of sarcopenia to a standard model for prediction of disease progression improved the discrimination of the model from 62% to 70%. DCA revealed superior net benefits for the proposed model in comparison to the strategies of treating all or no patients with radical cystectomy, and in comparison to the existing predictive model. Limitations are inherent to the retrospective design. Conclusions: We demonstrated the prognostic role of sarcopenia in T1 HG NMIBC. Pending external validation, this tool could be easily incorporated into existing nomograms for prediction of disease progression to improve clinical decision-making and patient counseling. Patient summary: We looked at the role of loss of skeletal muscle (sarcopenia) as a factor in predicting prognosis for stage T1 high-grade non–muscle-invasive bladder cancer. We found that sarcopenia is a ready-to-use, cost-free marker that could be used to guide treatment and follow-up in this disease, although the results need to be confirmed in other studies.