The impact of sarcopenia and myosteatosis on outcomes of unresectable pancreatic cancer or distal cholangiocarcinoma

Abstract

Patients with pancreatic cancer have a poor prognosis, are often cachectic, and frequently demonstrate features of systemic inflammation, which may contribute to the phenomenon of myosteatosis. Analysis of body composition from CT scans has been used to study sarcopenia and its association with prognosis in a number of types of cancer, particular in combination with obesity. It has also been suggested that myosteatosis, defined as attenuated mean skeletal muscle Hounsfield units (HU), is associated with reduced survival in cancer. This study aimed to assess the association between body composition (sarcopenia and myosteatosis) and outcome in patients with unresectable pancreatic cancer. All patients diagnosed with unresectable pancreatic cancer at Nottingham University Hospitals NHS Trust between 2006 and 2013 were considered for the study. A total of 228 patients were included retrospectively. Body composition was assessed using cross-sectional CT analysis to calculate a skeletal muscle index (SMI) for sarcopenia and use mean skeletal muscle HU for myosteatosis. The prevalence of sarcopenia in the whole patient group at baseline was 60.5% (138/228). Overall, patients who were sarcopenic had no significant difference in overall survival versus those who were not (p=0.779). However, patients who were overweight/obese and sarcopenic had a significantly lower survival (p=0.013). Of the 58 patients who were overweight or obese and sarcopenic, 32 were also myosteatotic. The prevalence of myosteatosis overall at baseline was 55.3% (126/228) and this was associated with significant reduction in overall survival (p=0.049). Univariate Cox regression revealed myosteatosis but not sarcopenia to be predictive of reduced survival, however this relationship was lost on multivariate testing. Myosteatosis was associated with significantly greater levels of systemic inflammation (white cell count, neutrophil-lymphocyte ratio and C-reactive protein), anaemia and worsening of baseline blood urea. This relationship was not seen with sarcopenia. This is the largest study on the association between body composition and survival in patients with unresectable pancreatic cancer and has shown that although sarcopenia alone did not have a bearing on survival, the presence of myosteatosis was associated significantly with the presence of systemic inflammation and reduced survival.