Primary tumor location is a risk factor for postoperative development of sarcopenia as a predictive marker for unfavorable outcomes in patients with colorectal cancer.

Abstract

Background: The impact of the skeletal muscle volume after colorectal cancer surgery is unclear. Thus, we investigated the change of skeletal muscle mass after surgery and its effects on long-term outcomes.

Methods: This retrospective analysis included clinical stage I-IV colorectal cancer patients who underwent curative resection between April 2012 and March 2014 in our hospital. The psoas muscle area at the third lumbar vertebra level was evaluated by computed tomography and was divided by the square of height to obtain the psoas muscle mass index (PMI). Sarcopenia was defined using the PMI cut-off values for Asian adults of 6.36 cm²/m² for males and 3.92 cm²/m² for females.

Results: Among eligible 354 patients, 166 and 145 had pre- and postoperative sarcopenia one year after surgery, respectively. Five-year disease-free survival (DFS) and overall survival (OS) rates were 81.7% and 94.5%, respectively. In multivariate analysis, postoperative sarcopenia was an independent risk factor for shorter DFS [hazard ratio (HR) 1.71, p = 0.0171] and OS (HR 2.42, p = 0.0455), respectively, but preoperative sarcopenia was not a prognosticactor for either. One year after colorectal resection, 24 patients (6.8%) were newly diagnosed with sarcopenia, while 45 (12.7%) recovered from sarcopenia. Rectal cancer was identified as an independent risk factor for the postoperative development of sarcopenia (odds ratio 3.12, p = 0.0440).

Conclusion: Postoperative sarcopenia one year after surgery was associated with poor DFS and OS. Thus, clinicians need to consider skeletal muscle loss during postoperative surveillance, particularly in rectal cancer patients without sarcopenia before surgery.