Temporalis Muscle Width as a Measure of Sarcopenia Independently Predicts Overall Survival in Patients with Newly Diagnosed Glioblastoma

Abstract

Multiple prognostic factors, including age and performance status, are used to determine treatment recommendations in newly diagnosed glioblastoma (GBM). Sarcopenia, or clinically evident muscle wasting, has recently been shown to correlate with shorter overall survival (OS) in patients with newly diagnosed brain metastases. The prognostic value of sarcopenia and the optimal method to evaluate sarcopenia in patients with GBM are unclear. Measurements of the psoas and temporalis muscles have been used to quantify sarcopenia. We sought to develop a method to reproducibly quantify sarcopenia using the temporalis muscle, and evaluate the potential correlation between sarcopenia and outcomes for patients with GBM. We conducted a retrospective analysis of post-operative treatment planning CT simulation scans of 87 newly diagnosed GBM patients from 2012 to 2016. All patients received standard of care chemoradiation therapy including conventionally fractionated radiotherapy to a total dose of 6000 cGy in 30 fractions with concurrent temozolomide. We measured the temporalis muscle width (TMW) bilaterally on four axial CT slices to approximate muscle volume and evaluated the potential correlation between the TMW and OS. Selection of axial slices was defined by bony orbital anatomy: supraorbital, superior quartile (equidistant from supraorbital and mid-orbital), mid-orbital, and inferior quartile (equidistant from mid-orbital and infraorbital) locations. TMW measured on the inferior quartile slice correlated most strongly with OS. TMW was dichotomized at the median measurement (wide, >1.58 cm vs. narrow, ≤1.58 cm). OS for patients with wide TMW (>1.58 cm) was statistically significantly greater than that of patients with narrow TMW (<1.58 cm): 28.3 mo vs 22.2 mo, independent of age, gender, body mass index, Karnofsky Performance Status and resection type ((HR(wide/narrow)=0.42, 95% CI=(0.20, 0.90), adjusted p=0.03). This was especially pronounced in the following patient subsets: females (HR(wide/narrow)=0.26, 95% CI=(0.07, 0.92), p=0.04), and age ≤ 60 years (HR=0.32, 95% CI=(0.13, 0.81), adjusted p=0.02). The temporalis muscle width was used to quantify sarcopenia and found to be independently prognostic of OS in our GBM cohort. Prospective validation of sarcopenia is needed to evaluate its potential in determining optimal patient treatment.