Abstract 761: Body composition and overall survival in esophageal cancer patients
Authors: Loehrer Elizabeth , Weiss Jakob , Mak Raymond H. , Lu Junwei , Shafer Andrea , Rosenthal Michael H. , Aerts Hugo J. , Christiani David C. 
Published: July 2021

Abstract
Aim: We studied body composition throughout the first year after diagnosis and its association with overall survival (OS) among esophageal cancer patients.
Methods: We utilized clinical abdominal computerized tomography (CT) scans from esophageal adenocarcinoma (EA) and squamous cell carcinoma (SCC) patients, who were diagnosed between 1999 and 2018 and enrolled in an ongoing study at Massachusetts General Hospital. A deep learning based automated segmentation of each CT at the L3 slice to obtain muscle (MA), subcutaneous adiposity tissue (SAT), and visceral adiposity tissue (VAT). These measures were normalized by age-, sex-, and race using a published cohort of non-cancer patient CT body composition database. We defined baseline sarcopenia using the Martin et. al. 2013 cut points. Among available scans, we obtained HRs for body composition metrics throughout the first year after diagnosis (3-6 months, 6-9 months, 9-12 months) using conditional follow-up and time-varying metrics. We obtained OS hazard ratios (HR) for pre-treatment baseline metrics using an extended cox proportional hazard model. Multivariable models included smoking status, histology, chemotherapy, radiation, and time-dependent surgery as covariates, and baseline hazards were stratified by lymph node status at diagnosis (lymph node negative, lymph node positive, and metastatic). We performed additional sensitivity baseline analyses restricting to EA patients, patients who received trimodality therapy, and stratified by lymph node status.
Results: 251 patients (80.9% EA) had pre-treatment CT scans, and 438 patients (85.4% EA) had at least one CT scan throughout the first year after diagnosis. In the complete cohort, normalized baseline body composition measures and sarcopenia were not associated with OS in the univariable or multivariable analyses. Among EA only, baseline MA was associated with longer survival (HR: 0.85 per standard deviation increase; 95% CI 0.73-0.99; p=0.04). 3-6 months after diagnosis (N=206 patients), higher normalized MA, SAT, and VAT were all significantly associated (p&lt;0.04) with longer survival. The association between SAT and OS remained consistent in the first year after diagnosis, but VAT was not associated with OS &gt;6 months after diagnosis. The strongest association was 9-12 months after diagnosis (N=131), where a standard deviation increase in MA was associated with 0.56 hazard of death (95%CI 0.42-0.75; p&lt;0.001).
Conclusions: Muscle area in the first year after diagnosis is strongly associated with survival in esophageal cancer. Since associations were strongest during and after treatment, directionality of this association is uncertain, and we will investigate additional factors to determine the clinical utility of these associations.
Citation Format: Elizabeth Loehrer, Jakob Weiss, Raymond H. Mak, Junwei Lu, Andrea Shafer, Michael H. Rosenthal, Hugo J. Aerts, David C. Christiani. Body composition and overall survival in esophageal cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 761.