SSAT - INDUCTION THERAPY FOR ESOPHAGEAL CANCER SIGNIFICANTLY ALTERS CT-DERIVED BODY COMPOSITION AND SURGICAL RISK

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INDUCTION THERAPY FOR ESOPHAGEAL CANCER SIGNIFICANTLY ALTERS CT-DERIVED BODY COMPOSITION AND SURGICAL RISK
Ernest G. Chan^*¹, Darren Bryan¹, Jules Lin², Maria L. Madrariaga¹, Brian A. Derstine², Pablo G. Sanchez¹, Stewart C. Wang², Mark Ferguson¹
¹Surgery, University of Chicago, Chicago, IL; ²University of Michigan, Ann Arbor, MI

Background
We assessed body composition (BC) before and after induction therapy for esophageal cancer to identify changes that might affect risks of esophagectomy.

Methods
We performed a retrospective single institution analysis of patients who underwent esophagectomy for esophageal cancer who received neoadjuvant chemoradiation prior to surgery. Pre-induction and pre-surgical CT studies underwent semi-automated segmenting focusing on muscle area (both low density (LD) and normal density (ND) areas), visceral adipose tissue (VAT) area, and trabecular bone density at L3. Metrics were normalized by gender, age, and height. The relationships among these pre and post induction measurements were analyzed. A previously published body composition index assigned a point each time a metric for a patient was in the lowest normalized tertile, and the values were summed to yield a BC index score (range 0 to 3).

Results
We included 82 patients with a median age of 62.5 years; 128 (82%) were male. LD muscle area was inversely correlated with ND muscle area pre and post therapy (p=.001 for each). VAT area was directly correlated with LD muscle area both pre and post induction (p<.001). Body weight, ND muscle area, and visceral adipose tissue area were significantly decreased following induction therapy (p<0.001 for each). Percent change in overall muscle (p=.013) and VAT (p<.001) were directly correlated with the percent change in body weight following induction therapy. Compared to pre-induction metrics, the preoperative measurements demonstrated LD muscle area increased 3.0% whereas ND muscle decreased 6.0% and VAT area decreased 11.5% (Figure 1; p=.003 by ANOVA). The change in distribution of patients among the body composition surgical risk index levels was significant, with 24 (36%) of patients experiencing migration to a higher risk score (Figure 2; p<.001).
Conclusion
Our analysis identified unique changes in body composition that are more granular than the metric of body weight. The increase in LD muscle area and decrease in ND muscle area help our understanding of the complex changes in BC during induction therapy and may explain decreased strength and vigor evident in our preoperative patients. Further studies are needed to assess the association between these findings and outcomes following esophagectomy.

Compared to pre-induction metrics, the preoperative measurements demonstrated LD muscle area increased 3.0% whereas ND muscle decreased 6.0% and VAT area decreased 11.5%.

The change in distribution of patients among the body composition surgical risk index levels was significant, with 24 (36%) of patients experiencing migration to a higher risk score (p<.001).

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