Decreased Skeletal Muscle Volume Is a Predictive Factor for Poorer Survival in Patients Undergoing Surgical Resection for Pancreatic Ductal Adenocarcinoma

Background: The aim of this study was to investigate the impact of decreased skeletal muscle (SM) volume on survival outcomes in patients undergoing surgical resection for pancreatic ductal adenocarcinoma (PDAC). Methods: Between March 2000 and February 2015, 323 patients who underwent upfront surgical resection for PDAC were identified from the Mayo Clinic SPORE in Pancreatic Cancer. Body composition data, including SM area, subcutaneous adipose tissue area, and visceral adipose tissue area were calculated using an abdominal computed tomography (CT) image at the third lumbar spinal level. The body composition data were normalized by patients’ height (e.g., SM index, cm²/m²) and analyzed as continuous variables. Clinicopathological findings and body composition data at initial diagnosis were evaluated for association with overall survival and recurrence-free survival. Results: Because the median SM index was significantly different between males vs. females (49.9 cm²/m² [range, 32.0–70.3] vs. 39.4 cm²/m² [range, 29.2–66.2], P < 0.001), it was standardized for each sex and used for further analyses. Parameters independently associated with a shorter overall survival were a larger tumor size (P = 0.007), a greater tumor extent (P = 0.037), a higher carbohydrate antigen 19–9 level (P < 0.001), and a smaller sex-standardized SM index (P = 0.011). Parameters independently associated with a shorter recurrence-free survival were female sex (P = 0.029), a larger tumor size (P < 0.001), a higher carbohydrate antigen 19–9 level (P = 0.001), and a smaller sex-standardized SM index (P = 0.007). Conclusions: A smaller sex-standardized SM index is a predictive factor for shorter overall and recurrence-free survival in PDAC patients undergoing surgery.