The Impact of Edema on Skeletal Muscle Changes among Patients with Pancreatic Ductal Adenocarcinoma

Abstract

Background: Muscle loss influences pancreatic ductal adenocarcinoma (PDAC) outcomes, but treatment-related edema may cause overestimation of total skeletal muscle area (tSMA), confounding our understanding of muscle changes. However, no studies have quantified the impact of edema on tSMA and psoas skeletal muscle area (pSMA) changes. Thus, we sought to (i) assess the impact of edema on tSMA and pSMA changes between diagnosis and follow-up and (ii) explore the utility of pSMA as a clinically relevant measure of muscle and muscle loss among patients with PDAC.

Methods: Body composition was measured using CT scans at diagnosis and follow-up from 95 patients enrolled in the Florida Pancreas Collaborative cohort study. Edema was assessed by opacifications in subcutaneous fat, and tSMA and pSMA changes were expressed as percent change between diagnosis and follow-up. We used multivariable generalized linear models to estimate mean tSMA and pSMA changes overall and by edema status. Spearman correlation was used to measure interrelationships of tSMA and pSMA.

Results: tSMA increased between diagnosis and follow-up (Δ = 0.66) but only in patients with edema (Δ = 3.35) whereas non-edematous patients lost tSMA (Δ = -2.03). Conversely, pSMA decreased regardless of edema status. Furthermore, tSMA and pSMA were strongly correlated overall (r = 0.75) and in non-edematous patients (r = 0.83).

Conclusions: Edema inflated estimates of tSMA at follow-up in patients with PDAC, but pSMA was impervious to edema and may represent a suitable proxy for tSMA.

Impact: pSMA is a reliable measure of muscle and muscle loss and should be considered in future studies assessing muscle loss in patients with PDAC.