Change in Psoas Muscle Volume as a Predictor of Outcomes in Patients Treated with Chemotherapy and Radical Cystectomy for Muscle-Invasive Bladder Cancer

Objective: Sarcopenia, or the age-related loss of skeletal muscle mass and function, has been investigated as a potential marker of adverse outcomes among surgical patients. Our aim was to assess for changes in psoas muscle volume (PMV) following administration of neoadjuvant chemotherapy (NAC) in patients with bladder cancer and to examine whether changes in PMV following NAC are predictive of perioperative complications, pathologic response or survival. Methods: During the period of 2009-2013, patients undergoing NAC and radical cystectomy (RC) at our institution with pre and post NAC cross sectional images available were included. Bilateral total psoas muscle volume (PMV) was obtained from pre- and post- NAC images and the proportion of PMV change was calculated by dividing the change PMV by pre-NAC PMV. Analyses for the assessment of factors predicting PMV loss, partial/complete pathologic response (pPR/pCR), complications, readmission, cancer specific (CSS), recurrence-free (RFS) and overall survival (OS) were performed. Results: Total of 60 patients had complete radiological data available. Post-NAC PMV and BMI declines were statistically significant, 4.9% and 0.05%, respectively. NAC dose reduction/delay was a significant predictor of PMV loss (coefficient B 4.6; 95% CI 0.05-9.2; p = 0.047). The proportion of PMV decline during NAC was not a predictor of pPR, pCR, complications, readmission, CSS, RFS, or OS. Conclusions: We observed an interval decline in PMV during the period of NAC administration and this decline was more than it could be appreciated with changes in BMI during the same period. PMV decline was associated with the need for dose reduction/dose delay during NAC. In our series, PMV changes occurring during NAC administration were not predictive of pathologic response to chemotherapy, postoperative complications or survival.