Association Between Sarcopenia, Clinical Outcomes, and Survival in Patients with Extensive-Stage Small Cell Lung Cancer Treated with First-Line Immunochemotherapy: A Prospective Cohort Study.

Objective: To investigate the association between sarcopenia, short-term efficacy, and long-term survival in patients with extensive small-cell lung cancer (SCLC) treated with standard first-line immunochemotherapy.

Methods: A total of 63 patients initially diagnosed with extensive-stage small cell lung cancer were enrolled in the prospective study from December 1, 2020 to December 31, 2022. The clinical characteristics, body composition, blood test results, and image data were obtained before treatment. Patients were divided into sarcopenia and non-sarcopenia groups according to the diagnostic criteria of the Asian Sarcopenia Working Group 2019. The primary outcome was overall survival (OS) and comprehensive survival analyses were performed. Secondary outcomes included short-term efficacy and adverse events associated with first-line immunochemotherapy.

Results: The median age of the 63 patients enrolled in our study was 63.0 years (40-80 years). The incidence of sarcopenia was 19.0% (12/63) in patients with extensive SCLC. Compared with non-sarcopenia patients, extensive-stage SCLC patients with sarcopenia were significantly older (69.0 vs. 62.0, P = 0.017), and had lower body mass index (BMI) (20.29 vs. 24.27, P < 0.001), hand grip strength (HGS) (20.42 vs. 30.75, P < 0.001), and albumin (35.9 vs. 41.40, P < 0.001). The objective response rate after two cycles of standard first-line immunochemotherapy in the sarcopenia group was lower than in the non-sarcopenia group (30.0 vs. 78.9%, P = 0.012). There was no significant difference in chemotherapy-related hematological toxicity between the two groups. During a median follow-up of 15 months (3-33 months), patients with extensive SCLC had a median OS of 24 months, with 1-year survival of 75% and 2-year survival of 52%, respectively. Compared to non-sarcopenia patients, the median OS in the sarcopenia group was significantly shorter (9 vs. 24 months, P = 0.0014). Multivariate Cox analysis showed that sarcopenia was an independent risk factor for OS in patients with extensive SCLC (HR = 4.993, 95%CI = 1.106-22.538, P = 0.037).

Conclusions: Patients with Extensive SCLC and sarcopenia had worse clinical outcomes and shorter OS. Sarcopenia is a prognostic factor affecting first-line treatment efficacy and long-term survival of patients with SCLC in the era of immunotherapy.