Psoas Cross-Sectional Area As Radiographic Measure Of Sarcopenia Does Not Predict Overall Survival In Multiple Myeloma
Authors: Bhamidipati Pavan Kumar , Carson Kenneth R , Wildes Tanya M 
Published: October 2019

Abstract

Introduction
Although various disease-related markers have been implemented in the prognosis of multiple myeloma, nutritional or physical characteristics have not been utilized in the assessment for prognosis. Sarcopenia, defined as loss of lean skeletal muscle mass, is prognostic in non-malignant diseases such as COPD and non-hematologic malignancies such as breast cancer and pancreatic cancer. For the first time, we sought to analyze the prognostic value of sarcopenia in multiple myeloma (MM) by utilizing PET / CT scans done around the time of diagnosis.

Methods
In this retrospective cohort study, we identified all patients diagnosed and treated for multiple myeloma from 2000-2010 from the Barnes-Jewish Hospital Oncology Data Services registry, then identified patients who had undergone cross-sectional imaging (CT or PET/CT) for diagnostic purposes within 2 months of diagnosis. Medical records were reviewed for clinical and anthropomorphic data. The radiographic images were accessed to manually measure the psoas muscle cross sectional area (PCA) at the level of 3rdlumbar vertebra (L3) by a single trained person. This landmark was chosen as the PCA at the level of L3 correlates with the whole–body lean muscle mass in previous studies (Mourtzakis M, 2008 PMID: 18923576).The psoas muscle density was identified based on the average CT Hounsfield units for the cross-sectional area being measured. This value was then normalized for stature based on height to calculate L3 muscle index (LMI)(Total Psoas Area (TPA), in cm2/m2). Overall survival was defined as the time from diagnosis to death from any cause, censored at last follow-up. Survival between tertiles of LMI was compared using the methods of Kaplan-Meier and the Log-Rank test.

Results
A total of 129 MM patients with radiographic imaging were identified (median age 61 years, range 32-91; 57% males; 66% white race, 31.8% black race). The median body mass index (BMI) was 28.7, range 16.6-49.9). Of the 93 patients with staging information available, 27% had ISS stage 1, 36.6% stage II, 36.6% stage III. The median OS for the entire cohort was 34.2 months (95% Confidence Intervals 23.5-45.0 months). Survival did not differ between the tertiles of LMI: median OS 26.9 months (95% CI 9.2-44.6) in lowest tertile of TPA, 54.1 months (95% CI 30.6-77.6) in middle tertile and 38.2 months in highest tertile [Log-rank c21.439, p=0.487]. We then evaluated psoas muscle density in the 56 patients who underwent abdominal CT imaging without intravenous contrast. Survival did not differ between the tertiles of psoas density: median OS 24.3 months (95% CI 10.3-38.2) in the lowest tertile, 33.8 months (95% CI 14.8-52.8) in middle tertile, and 44.8 months (95% CI 25.8 – 53.5) in the highest tertile, p=0.122.

Conclusion
Total psoas area and psoas density as a measure of sarcopenia did not predict overall survival in this cohort. Limitations of this study include the fact that patients underwent imaging for diagnostic purposes at clinician. Future study will evaluate whether radiographic measures of sarcopenia in a less selected MM population have prognostic utility.

Disclosures:
Carson: Spectrum Pharmaceuticals: Honoraria, Research Funding, Speakers Bureau.