Varying clinical relevance of sarcopenia and myosteatosis according to age among patients with postoperative colorectal cancer

The present retrospective study reviewed the association among sarcopenia, myosteatosis, and overall survival (OS) in patients with postoperative colorectal cancer (CRC) with regard to age. A retrospective study was conducted with a five-year follow-up. Data from all patients with CRC, who underwent surgery between February 2005 and April 2014, were reviewed. Data from 1053 patients (622 male 59.1%, 431 female 40.9%; mean ± SD age, 62.8 ± 11.8 years) were analyzed. Patients were divided into three groups according to age: ≤50, 51-74, and ≥75 years. Data, including perioperative parameters, and the presence of sarcopenia and myosteatosis according to skeletal muscle index (SMI) and skeletal muscle radiodensity (SMD), respectively, were collected. Sarcopenia was evaluated using CT by calculating the SMI at the L3 level by dividing the area of the skeletal muscle by height squared (cm2/m2). SMD was also calculated using CT at the L3 level, but by evaluating fat attenuation according to Hounsfield units (HU). Patient allocation according to age group was as follows: ≤50 years, n = 147 (14.0%); 51-74 years, n = 742 (70.5%); and ≥75 years, n = 164 (15.5%). The presence of sarcopenia and myosteatosis were statistically significant with increasing age (P = 0.004 and P < 0.001, respectively). The 51-74 years age group exhibited a significant association in OS for myosteatosis (P < 0.001) while the ≥75 years group was significantly associated with sarcopenia (P = 0.04) with regard to OS. Multivariable analysis also revealed a statistically significant association between myosteatosis in the 51-74 years age group (P = 0.033) and sarcopenia in the ≥75 years age group (P = 0.005) even when adjusted for recurrence status. Different age groups exhibited significantly variable skeletal muscle indices. Although an abundance of irrefutable results demonstrated a correlation between CT-defined sarcopenia, myosteatosis, and clinical prognosis, data regarding age-dependent correlations are scarce. Results of this study demonstrated that sarcopenia and myosteatosis did not influence the prognosis of young patients with postoperative CRC (≤50 years of age), inferring the existence of significantly different skeletal muscle-related parameters according to age. Patients over 75 years of age showed significant association with sarcopenia while those in the 51-74 age group displayed significant link to myosteatosis. Clinicians should consider the impact of sarcopenia and myosteatosis on patient prognosis and should also be aware that the effect may differ according to patient age.