Muscle Depletion Is an Important and Clinically Relevant Predictor of Outcomes after Autologous Hematopoietic Cell Transplantation

▪ Introduction: High intensity treatments such as autologous hematopoietic cell transplantation (HCT) can be curative for patients with relapsed/refractory lymphoma (Hodgkin [HL], non-Hodgkin [NHL]), but this needs to be balanced by the risk of non-relapse mortality (NRM) associated with HCT and potentially sub-optimal disease response with less intensive treatments. Measures of pre-treatment body composition such as quantity and quality of muscle are prognostic in patients with solid tumors, but their association with post-HCT outcomes is unknown. We examined the prognostic significance of muscle depletion prior to HCT, defined by having both low muscle quantity (lumbar skeletal muscle index [SMI]) and quality (muscle attenuation [MA]) on computed tomography (CT) imaging, in a population-based cohort of patients undergoing autologous HCT for lymphoma. Next, we examined the prognostic significance of muscle depletion after HCT in a subset of patients with normal muscle composition prior to HCT, allowing us to examine the impact of change in body composition over time. Methods: 440 consecutive patients with lymphoma, age ≥18y, who underwent a first HCT between 2009 and 2014 at a single institution were included in the study. Measures of muscle quantity (SMI) and quality (MA) were ascertained from pre- and post-HCT abdominal CT scans using image analysis software (SliceOmatic; Tomovision, Quebec, Canada). SMI was calculated as the ratio of skeletal muscle area (cm2) divided by height (m)2. Sex and body mass index (BMI)-specific cutoff values of low SMI and MA were used to identify patients with muscle depletion (J Clin Oncol 2013 31:1539). Measurements were made by trained researchers blinded to patient demographics and HCT outcome (Figure 1); 3rd lumbar vertebra was used as a landmark because of its high correlation with whole-body muscle mass (J Clin Oncol 2016 34:1339). This report is limited to 321 (73%) patients with CT scans performed ≤90 days from HCT. Cumulative incidence of NRM was calculated taking into consideration competing risk of disease-related mortality. Kaplan-Meier method was used to examine overall survival (OS). Multivariable Cox regression analysis was used to calculate the hazard ratio (HR) estimates and 95% confidence intervals (CI), adjusted for relevant covariates (demographics, diagnosis, pre-HCT Karnofsky performance score [KPS] and comorbidity index [HCT-CI]). Results: Sixty-two (19.3%) patients had muscle depletion pre-HCT. Medi