Impact of intramuscular adipose tissue content on short- and long-term outcomes of hepatectomy for colorectal liver metastasis: a retrospective analysis

Background Numerous reports regarding sarcopenia have focused on the quantity of skeletal muscle. In contrast, the impact of the quality of skeletal muscle has not been well investigated. Methods A retrospective analysis of 115 patients who underwent initial hepatectomy for colorectal liver metastasis between January 2009 and December 2016 in our hospital was performed. Intramuscular adipose tissue content (IMAC) was used to evaluate the quality of skeletal muscle by analysing computed tomography (CT) images at the level of the umbilicus. The impact of poor skeletal muscle quality on short-term and long-term outcomes after hepatectomy for colorectal liver metastasis was analysed. Results Patients were divided into two groups (high IMAC and normal IMAC) according to their IMAC values, and their backgrounds were compared. There were no significant differences in most factors between the two groups. However, both body mass index (P = 0.030) and the incidence of postoperative complications of Clavien-Dindo grade 3 or worse (P = 0.008) were significantly higher in the high-IMAC group. In multivariate analyses, an operative blood loss > 600 ml (P = 0.006) and high IMAC (P = 0.008) were associated with postoperative complications of Clavien-Dindo grade 3 or worse. Overall survival and recurrence-free survival were significantly lower (P < 0.001 and P = 0.045, respectively) in the high-IMAC group than in the normal IMAC group. In multivariate analyses for poor overall survival, high IMAC was associated with poor overall survival (P < 0.001). Conclusions IMAC is a prognostic factor for poor short- and long-term outcomes in patients with colorectal liver metastasis.