Sarcopenia as an independent prognostic indicator in patients with non-small cell lung cancer with brain metastases treated with Gamma Knife radiosurgery

Abstract

Sarcopenia is a syndrome that is associated with a poor prognosis in cancer patients. Temporal muscle thickness (TMT) is a novel biomarker of sarcopenia; however, its relevance in patients with brain metastasis (BMs) has not been exhaustively investigated. This retrospective study aimed to evaluate the prognostic efficacy of sarcopenia in patients with BMs from non-small cell lung cancer (NSCLC) who were treated with Gamma Knife radiosurgery (GKRS). Material and methods: In this single study, 82 patients with BMs from NSCLC were analyzed between January 2021 and February 2023; 59 (72%) had adenocarcinoma, 12 (14.6%) had squamous, 6 (7.3%) had large cell, and 5 (6.1%) had other histologies. On the basis of planning brain magnetic resonance imaging scans acquired prior to GKRS, TMT values were determined retroactively. Through multiplanar reformatting, TMT was evaluated as a measurement on a cranial thin T1WI contrast-enhanced image. Using the median value of bilateral TMT (9.85 mm) as the dividing line, patients with sarcopenia were distinguished from those with normal muscle status. Survival analysis was conducted utilizing the Kaplan-Meier and Cox regression models. Overall survival (OS) was defined as the time between disease treatment with GKRS and mortality or the date of the last follow-up assessment. After GKRS, 47 patients (57.3%) received immune checkpoint inhibitors and 35 patients (42.7%) received chemotherapy. The median length of follow-up was one year. Results: The cohort consisted of 50 males (61%) and 32 females (39%), with a mean age of 63 ± 5 years. There were 33 patients with a Karnofsky Performance Status (KPS) of 90 (40.2%), KPS 80 to 30 (36.6%), and KPS 70-19 (23.2%). There were 69 (84.1%) patients with extracranial metastasis (ECM) and 13 (15.9%) patients without ECM. The presence of sarcopenia was associated with both KPS (p < 0.001) and ECM (p = 0.013). Patients with sarcopenia had a significantly shorter median OS than patients without sarcopenia (6.00 months, 95% CI: 5.37-7.96 vs 18.00 months, 95% CI: 18.13-27.26; p < 0.001) (HR = 7.02, 95% CI 3.58-13.78; p<0.001). Moreover, when controlling for age, gender, KPS, and number of BMs, the presence of sarcopenia was an independent marker of poor prognosis in a multiple Cox regression model (HR = 2.43, 95% CI 1.02-5.74; p < 0.043). Conclusion: Sarcopenia is an independent marker of poor prognosis in NSCLC patients with BMs, who were treated with GKRS.