P-222 Prognostic value of skeletal muscle area at diagnosis in patients with metastatic colorectal cancer: A single institution experience

Sarcopenia is a poor prognostic feature of patients with cancer. Skeletal muscle area is a surrogate marker for sarcopenia. We aim to assess the prognostic value of the SMA at diagnosis in patients with metastatic colorectal cancer (mCRC). This is an observational retrospective study. We included all the patients with diagnosis of de novo mCRC from January 2017 to June 2018 at Hospital Universitario La Paz. We measured the skeletal muscle area at diagnosis using Image J software. A total of 81 patients were included. Seventy percent of the patients were men, and 87% had ECOG 0/1 at diagnosis. Primary tumors were located in right/left colon/rectum in 33, 36, and 31% of the patients, respectively. Median skeletal muscle área (SMA) at diagnosis was 117,7 cm2 (range: 66 to 205 cm2). We selected 113,92 cm2 as the cutt-off value for SMA based upon the Youden Index of the area under the curve (AUC) for survival at 36 months (AUC: 0.71, p = 0.014). Forty-eight patients (59%) had a high SMA. High SMA was significantly associated with male sex (p < 0.001) and with receiving active treatment rather than best supportive care (p = 0.005). SMA was also directy correlated with albumin levels (r = 0.254; p = 0.02). After a median follow up of 41 months, 59 deaths were observed. Median overall survival was 10.8 months (95% confidence Interval (CI): 0,0 to 22.1) in the low SMA group and 19,2 months (95%CI: 7.2 to 31.3) with a Hazard Ratio (HR) for death of 0.57 (95%CI: 0.34 to 0.95); p = 0.034. At 36 months, 34% and 14% of the patients remain alive in the high and low SMA cohorts, respectively. In our study, SMA at diagnosis was an adverse prognostic factor for survival in patients with mCRC. Larger real-world data and interventional studies are needed to confirm this results and improve the outcomes these patients.