Evaluating Immunotherapy Outcomes in Elderly Patients with Extensive-Stage Small-Cell Lung Cancer (KCSG LU23-15).

Abstract

Purpose Chemoimmunotherapy has improved outcomes in extensive-stage small-cell lung cancer (ES-SCLC), but its benefit in older adults remains uncertain because this population is underrepresented in clinical trials. We evaluated the real-world efficacy of first-line atezolizumab plus etoposide-carboplatin according to age in patients with ES-SCLC. Materials and Methods We conducted a multicenter retrospective study across seven Korean institutions and identified patients with ES-SCLC treated between 2016 and 2022 with atezolizumab plus etoposide-carboplatin or etoposide-platinum chemotherapy alone. Patients with recurrence after prior limited-stage disease or incomplete records were excluded. End points were overall response rate (ORR), progression-free survival (PFS), and overall survival (OS), assessed using Kaplan-Meier methods and Cox regression models. Results Among 550 identified patients, 538 were included: 247 received atezolizumab plus chemotherapy and 291 received chemotherapy alone. Overall, 111 patients (20.2%) were aged 75-80 and 57 (10.4%) were older than 80years. In the overall population, atezolizumab was associated with improved PFS (hazard ratio [HR], 0.78; 95% CI, 0.65 to 0.93; p=0.006) and OS (HR, 0.76; 95% CI, 0.63 to 0.93; p=0.006). Age-stratified analyses showed significant PFS benefit only in patients aged 70-75 (HR, 0.67; p=0.049) and significant OS benefit only in patients aged 65-70 (HR, 0.65; p=0.044). Beyond 75 years, neither PFS nor OS was significantly improved. Patients aged ≥75years also had lower ORR and more progressive or non-evaluable disease compared with <75years. Conclusion The clinical benefit of adding atezolizumab appears attenuated in ES-SCLC patients age 75 years or older, supporting careful selection and age-adapted treatment strategies.