# Preoperative Temporal Muscle Volume as an Independent Prognostic Marker in Glioblastoma

## TL;DR

This study shows that the volume of the temporal muscle before surgery is a new independent predictor of survival in glioblastoma patients.

## Contribution

The study identifies preoperative temporal muscle volume as an independent prognostic marker in glioblastoma, distinct from other clinical and molecular factors.

## Key findings

- Low temporal muscle volume was associated with shorter median overall survival (312 vs 492 days).
- Temporal muscle volume remained independently associated with reduced mortality risk in multivariable analysis.
- Temporal muscle volume correlated positively with survival time (Spearman r = 0.37).

## Abstract

Background and objective: Sarcopenia has emerged as a relevant prognostic factor across solid tumors, but its impact in glioblastoma is not fully defined. Temporal muscle measurements on routine cranial imaging offer a pragmatic surrogate of systemic muscle mass in patients who rarely undergo body computed tomography (CT). This study aimed to evaluate whether preoperative bilateral temporal muscle volume is associated with overall survival in adults with glioblastoma, independently of established clinical and molecular prognostic factors.

Methods: We conducted a retrospective, single-center cohort study including 83 adults with histologically confirmed glioblastoma who underwent tumor-directed neurosurgical procedures between January 2020 and July 2024 and had preoperative imaging suitable for temporal muscle assessment. Bilateral temporal muscle volume was obtained by summing right and left temporal muscle volumes and analyzed as a continuous variable and as a dichotomous variable based on the cohort median. Overall survival, defined from last tumor-directed surgery to death or last follow-up, was analyzed using Kaplan-Meier methods and Cox proportional hazards regression adjusted for age, sex, preoperative Karnofsky Performance Status, surgery type, postoperative treatment, isocitrate dehydrogenase mutation status, and O6-methylguanine-DNA methyltransferase promoter methylation status.

Results: Patients in the low-volume group had shorter median overall survival than those in the high-volume group (312 vs 492 days, log-rank p = 0.003). Temporal muscle volume correlated positively with survival time (Spearman r = 0.37, p = 0.001), whereas age correlated negatively (r = −0.35, p = 0.002). In multivariable analysis, higher temporal muscle volume remained independently associated with reduced mortality risk (hazard ratio per standard-deviation increase 0.68, 95% confidence interval 0.52-0.89, p = 0.004).

Conclusion: Preoperative bilateral temporal muscle volume is an independent prognostic marker in glioblastoma and may help refine risk stratification and guide supportive care in routine neuro-oncologic practice.