Beyond tumor burden: PET/CT-derived psoas muscle quality and survival outcomes in metastatic NSCLC patients treated with nivolumab
摘要
Reliable host-related biomarkers for prognostic outcomes in immunotherapy non-small cell lung cancer (NSCLC) remain limited. Although sarcopenia has been associated with poor prognosis, the relative contributions of muscle quantity, muscle quality, and muscle metabolic activity during immune checkpoint inhibitor (ICI) therapy are unclear. This study evaluated PET/CT–derived psoas muscle parameters as host-related prognostic biomarkers in metastatic NSCLC patients treated with nivolumab.
MethodsIn this multicenter retrospective study, 172 stage IV NSCLC patients receiving second-line nivolumab monotherapy were analyzed. Baseline PET/CT scans were used to assess tumor metabolic burden and psoas muscle characteristics. Muscle quantity was defined by psoas muscle index, muscle quality by mean Hounsfield unit (HU) attenuation, and muscle metabolic activity by SUVmax and SUVmean. Factors associated with progression-free survival (PFS) and overall survival (OS) were analyzed using univariable and multivariable Cox proportional hazards regression models.
ResultsIn the overall cohort, median PFS and OS were 3.7 and 10.9 months, respectively. In multivariable analysis, psoas muscle HUmean was independently associated with OS (HR 0.959, 95% CI 0.931–0.988, p = 0.005), whereas PET-derived muscle metabolic parameters did not retain independent prognostic significance. Lower Programmed Death-Ligand 1 (PD-L1) expression (< 1%) (p = 0.019), higher total tumor metabolic volume (p = 0.025), and lower Advanced Lung Cancer Inflammation Index (ALI) scores (p = 0.038) were also independently associated with worse OS. Although patients with sarcopenia demonstrated shorter OS, sarcopenia based solely on muscle quantity was not independently associated with survival outcomes in multivariable analysis.
ConclusionsImaging-derived muscle quality assessed on routine PET/CT was independently associated with survival in metastatic NSCLC patients receiving nivolumab. Radiologic muscle attenuation, together with systemic host-related factors, may improve prognostic stratification beyond tumor burden alone.