NIMG-34. TEMPORAL MUSCLE THICKNESS AS A PROGNOSTIC MARKER IN A REAL-LIFE COHORT OF NEWLY DIAGNOSED MGMT PROMOTER METHYLATED GLIOBLASTOMA PATIENTS: A MULTICENTRIC IMAGING ANALYSIS

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Abstract BACKGROUND In cranial MRI assessed temporal muscle thickness (TMT) correlates with lumbar skeletal muscle mass, which serves as surrogate marker of sarcopenia. Prior research has identified TMT as a prognostic marker in glioblastoma. However, incorporation into clinical practice is challenging due to the heterogeneity of previous studies and the absence of established cutoff values. To address this, we conducted a multicenter analysis to validate recently proposed sex-specific cutoff values in a homogeneous real-life cohort of newly diagnosed MGMT promoter-methylated glioblastoma patients uniformly treated with combined CCNU/temozolomide. We implemented a balanced control cohort for comparison. METHODS TMT was measured at baseline using preoperative or early postoperative MRI and in the disease course using the first MRI after completion of radiotherapy. Patients were TMT-based divided into “at risk of sarcopenia” or “normal muscle status”. Kaplan-Meier statistics and multivariable Cox regression analysis were used for correlation with survival. RESULTS In total, n = 126 patients were analyzed (n = 66 received CCNU/temozolomide; n = 60 received temozolomide). Patients with normal muscle mass at baseline (> 6,3 mm for men; > 5,2 mm for women) had significantly prolonged mOS (44.3 versus 16.7 months for CCNU/temozolomide; 29.5 versus 17.4 months for temozolomide) compared to those at risk of sarcopenia. In a multivariable Cox regression analysis, normal muscle mass (HR: 0.39, 95% CI: 0.23-0.66; p = 0.0003) and age at diagnosis of < 50 years (HR: 0.42, 95% CI: 0.22-0.79; p = 0.0067) were significant prognostic markers. Longitudinally, survival was best in patients with lack of TMT decline. CONCLUSIONS This analysis suggests TMT to serve as a prognostic marker in glioblastoma patients treated with CCNU/temozolomide or with temozolomide. However, for TMT assessment to be implemented in a generalizable manner, such as for patient selection for therapeutic measures, further validation in prospective controlled trials is necessary.