Temporalis and Masseter Muscle Volume as Prognostic Indicators of Overall Survival in Glioblastoma

Introduction: Glioblastoma (GBM) is an aggressive primary brain cancer with an average survival of 1.5 years. Sarcopenia has been shown to be associated with poor overall survival (OS) in multiple cancers. Both temporalis and masseter muscle thickness have been used as proxies for diagnosing sarcopenia in GBM. Muscle volume has been established as a prognostic indicator in other cancers. Our study investigates temporalis muscle volume (TMV) or masseter muscle volume (MMV) as prognostic indicators of OS in GBM.

Methods: Cases of GBM were identified within a tertiary care center. Inclusion criteria were newly diagnosed GBM, age ≥ 18, Karnofsky Performance Scale (KPS) ≥ 60, and IDHwt. Demographic and clinical characteristics were extracted from the medical record. TMV and MMV were measured on CT using Varian Eclipse v18.0TM. Correlation analysis and Kaplan-Meier estimates of OS were completed.

Results: 99 patients were included in our study with a mean age of 58 years (SD 12). The population was skewed towards male sex (71%) and the mean BMI was 28.9 (SD 5.6). Correlation between muscle thickness and volume was high. Mean TMV and MMV were 34.0 cm3 and 24.6 cm3 (SD = 11.9 cm3; SD = 8.3 cm3 respectively). For TMV, older age at resection (HR 4.29; 95% CI: 1.71-10.8) and subtotal resection (HR 3.12; 95% CI: 1.63-5.94) demonstrated worse OS, while MGMT methylation (HR 0.35; 95% CI: 0.20-0.61) was protective. MMV demonstrated similar results. Neither TMV nor MMV were significantly associated with OS, though TMV approached significance (p = 0.066).

Conclusion : Both advanced age at resection and subtotal extent of resection worsen prognosis for GBM patients, while MGMT methylation improved prognosis. Our results did not demonstrate a significant association between TMV or MMV with OS, though TMV may show promise. Larger studies investigating muscle volume as prognostic indicators in GBM are warranted.