Prognostic value of adipose tissue and muscle mass in advanced colorectal cancer: a post hoc analysis of two non-randomized phase II trials

BACKGROUND: The prognostic value of body composition in cancer patients has been widely studied during the last decade. The main finding of these studies is that sarcopenia, or skeletal muscle depletion, assessed by CT imaging correlates with a reduced overall survival (OS). By contrast, the prognostic value of fat mass remains ill-defined. This study aims to analyze the influence of body composition including both muscle mass and adipose tissue on OS in a homogeneous population of advanced colorectal cancer (CRC) patients. METHODS: Among 235 patients with chemorefractory advanced CRC included in the SoMore and RegARd-C trials, body composition was assessed in 217 patients on baseline CT images. The relationship between body composition (sarcopenia, muscle density, subcutaneous and visceral fat index and density), body mass index (BMI) and OS were evaluated. RESULTS: Patients with a higher BMI had a better OS (≥30 versus < 30, HR: 0.50; 0.33–0.76). Those with low muscle index and muscle density had an increased mortality (HR: 2.06; 1.45–2.93 and HR: 1.54; 1.09–2.18, respectively). Likewise, low subcutaneous and visceral fat index were associated with an increased risk of dying (HR: 1.63; 1.23–2.17 and 1.48; 1.09–2.02 respectively), as were a high subcutaneous and visceral adipose tissue density (HR: 1.93; 1.44–2.57 and 2.40; 1.79–3.20 respectively). In multivariate analysis, a high visceral fat density was the main predictor of poor survival. CONCLUSIONS: Our results confirm the protective role of obesity in CRC patients at an advanced stage, as well as the negative prognostic impact of muscle depletion on survival. More importantly, our data show for the first time that visceral adipose tissue density is an important prognostic factor in metastatic CRC. TRIAL REGISTRATION: NCT01290926, 07/02/2011 and NCT01929616, 28/08/2013.