ThTP2.12 The impact of acute systemic inflammation and the metabolic response to surgery on computed tomography body composition analyses

Abstract

Abstract Aim Body composition has been used extensively for prognostication across malignant and benign diseases. Systemic inflammation is both a key driver of cancer cachexia and a common finding in patients presenting with acute pathology. However, its influence on body composition is poorly understood. This study aimed to longitudinally assess computed tomography (CT) body composition, in patients who experienced an anastomotic leak post-oesophagectomy, as a model of acute, severe systemic inflammation. Methods Consecutive patients who suffered an anastomotic leak, following oesophagectomy, between 01/01/2012 and 01/01/2022 were identified from a prospectively maintained database. Changes in body composition were assessed across staging, pre-operative, post-complication and follow-up scans at the L3 vertebral level. Results Twenty patients (median 65 years, 90% male) were included. Of these, fifteen underwent neoadjuvant chemo(radio)therapy. Body composition was not altered by neoadjuvant treatment. Following surgery and anastomotic leak, a decrease in skeletal muscle volume (mean difference: -68.06cm3, p=0.028) was noted. Estimates of intramuscular and subcutaneous adipose tissue conversely increased (p=0.038 and p=0.039 respectively). Skeletal muscle density fell while adipose densities were higher following anastomotic leak. Although tissue radiodensity and subcutaneous fat volumes normalised on follow-up CT scans, skeletal muscle volume remained below pre-treatment levels. Conclusion Acute systemic inflammation has a marked effect on body composition analyses. Decreased muscle volume and increased volumes of adipose tissue were evident following the inflammatory insult. Radiodensity across muscle and adipose tissues trended towards that of water, likely secondary to oedema. Research utilising body composition variables should be interpreted with consideration of the potential of influence of underlying inflammatory status.