Impact of the preoperative quantity and quality of skeletal muscle on outcomes after resection of extrahepatic biliary malignancies

Background. Skeletal muscle depletion, referred to as sarcopenia, predicts mortality after major surgery. This study investigated the impact of preoperative skeletal muscle quantity and quality on outcomes in patients undergoing resection of extrahepatic biliary cancer. Methods. We performed a retrospective analysis of 207 patients undergoing resection for biliary cancer between 2004 and 2013. The quantity and quality of skeletal muscle, indicated by the psoas muscle mass index (PMT) and intramuscular adipose tissue content (IMAC), were measured on preoperative images of computed tomography. Overall survival (OS) and recurrence-free survival (RFS) rates were compared by PMI and IMAC, and prognostic factors after operation were assessed. Results. The OS and RFS rates were less in patients with low PMI (low muscle quantity) than in those with normal PMI (P <.001 and P <.001; 5-year OS, 15.7 vs 53.5 %). The OS and RFS rates were also less in patients with high IMAC (low muscle quality) than in those with normal IMAC (P <.001 and P <.001; 5-year OS, 23.8 vs 55.9%). Low PMI and high IMAC were independent factors predictive of poor OS (hazard ratio [HR], 2.921 [95% CI, 1.920-4.470; P <.001] and HR, 1.725 [95 % CI, 1.159-2.590; P =.007]) and RFS (HR, 2.141 [95% CI, 1.464-3.129, P <.001] and HR, 1.492 [95% CI, 1.032-2.166, P =.034]). Conclusion. Preoperative sarcopenia, indicating a low quantity and quality of skeletal muscle, is related closely to mortality after resection of biliary cancer.