Predictive impact of sarcopenia in advanced non-small cell lung cancer patients treated with immune checkpoint inhibitors: A retrospective study

Background: Sarcopenia, characterised by an ongoing loss of skeletal muscle mass and reduced strength and function, is frequently observed in patients with non-small cell lung cancer (NSCLC). However, the relationship between sarcopenia and the prognosis of NSCLC treated with immune checkpoint inhibitors (ICIs) remains unclear. This aimed to assess whether sarcopenia is an independent prognostic factor for survival in patients with advanced NSCLC receiving ICIs. Methods: For this retrospective cohort study, we analysed the medical records of patients attending our hospital aged 18 -75 years who were newly diagnosed with stage IIIB to stage IV NSCLC, and who had received ICIs as first- or second-line therapy between May 2019 and April 2022. The skeletal muscle index (SMI) was calculated from computed tomography (CT) images and relevant clinical characteristics within 4 weeks of initiating treatment and used to diagnose sarcopenia status. The Kaplan-Meier method and log-rank test were used to calculate and compare patients ' progression-free survival (PFS). Cox proportional hazard regression was used to examine the associations between sarcopenia and survival outcomes. The chi-square test was used to compare treatment response outcomes, such as the objective response rate (ORR), disease control rate (DCR), and immunotherapy-related adverse events (irAEs), between individuals with and without sarcopenia. Additionally, the Student 's t -test was utilised to compare SMI values between patients by their objective response (OR) and disease control (DC). Finally, the MannWhitney U test was used to compare nutritional and inflammatory indicators between the sarcopenia groups. Results: The study enrolled 70 patients, of whom 34 (48.6%) were diagnosed with sarcopenia. The median PFS of patients with and without sarcopenia was 7.5 vs. 13.4 months, respectively ( p = 0.006). The proportional hazards regression analysis showed sarcopenia to be an independent prognostic factor for shorter PFS (hazard ratio (HR): 0.504, 95% CI: 0.265 -0.962, p = 0.038). Using chi square tests, we found significant differences in the ORR (20.59% vs. 58.33%, p = 0.001) and occurrence of any irAEs (44.1% vs. 22.2%, p = 0.028) between the sarcopenia and the non-sarcopenia groups, respectively. The Student 's t -test showed a significant difference in SMI between the ORR group and the non-ORR group (49.99 +/- 7.00 vs. 42.98 +/- 2.18 cm 2 /m 2 , p = 0.0015). While the sarcopenia group were with significantly a lower CD4 + /CD8 + ratios and a higher C -reactive protein (CRP) level ( p = 0.026, p = 0.011, respectively). Conclusions: This study found that sarcopenia is a significant predictor of a poor prognosis for patients with advanced NSCLC receiving ICIs. Multiple inflammatory and immune functions related to prognosis also differ by sarcopenia status.