Are muscle parameters obtained by computed tomography associated with outcome after esophagectomy for cancer?

Esophageal cancer patients often suffer from cancer-related malnutrition and, as a result, sarcopenia. Whether sarcopenia worsens the outcome after esophagectomy is unclear. Inconsistent study results are partly caused by varying cut-off values used for defining sarcopenia. To overcome this challenge, a new statistical approach is proposed in this study: analyzing the linear association of computer tomography derived muscle parameters with important clinical short- and long-term outcomes post esophagectomy, regardless of cut-offs. Skeletal muscle index (SMI), quantifying muscle mass, was assessed with computed tomography (CT) in 98 patients undergoing esophagectomy. Muscle radiation attenuation (MRA) was measured to evaluate muscle quality. To evaluate the influence of the SMI and MRA on post-surgery complications, logistic regression models were used. To analyze the relationship of lengths of stay to muscle parameters, the competing risk approach introduced by Fine and Gray was applied. For survival analysis, log-rank test and Cox proportional hazards regression modeling were used. Neither a relevant association of SMI nor MRA with pneumonia and esophagoenteric leak were observed. Furthermore, no relevant association to lengths of stay in intensive care or hospital were detected. If the SMI increased, the odds for pleural effusion and pleural empyema decreased, but the odds of a pulmonary embolism increased. Univariate, unadjusted long-term survival analysis revealed that lower MRA and lower SMI were associated with shorter survival (P = 0.03). However, if the analysis was adjusted for confounders, e.g., Charlson Comorbidity Index, no relevant association regarding long-term survival was detected. Consequently, poor muscle status, determined by CT imaging, does not justify denying a patient an oncologic resection. The Charlson Comorbidity Index, however, was superior for preoperative risk stratification.