Neoadjuvant or conversion anti-PD-1/PD-L1 immunotherapy combined with chemotherapy improves 2-year survival and achieves high pathological complete response rate in patients with stage IIB-IIIB small-cell lung cancer.

Limited-stage small-cell lung cancer (LS-SCLC) is an aggressive malignancy, and patients with this disease have a poor long-term survival when treated with current standard chemoradiotherapy. Although neoadjuvant or conversion immunotherapy combined with chemotherapy has shown efficacy in patients with non-SCLC (NSCLC), its effect in those with LS-SCLC remains underexplored, particularly regarding long-term survival outcomes. This study aims to evaluate the efficacy and long-term survival of neoadjuvant or conversion immunotherapy plus chemotherapy in patients with LS-SCLC. This retrospective study enrolled 34 patients with stage IIB-IIIB SCLC who received neoadjuvant or conversion anti-programmed death-1 (PD-1)/programmed death-ligand 1 (PD-L1) immunotherapy plus platinum-etoposide chemotherapy, followed by surgical resection. The primary end points were overall survival (OS) and event-free survival (EFS). Pathological complete response (pCR) and major pathological response (MPR) were assessed, and subgroup analyses were performed based on pathological response, demographic factors, and tumor stage. With a median follow-up of 34.2 months, the 2-year EFS and OS rates were 72.1% [95% confidence interval (CI): 53.1-84.5%] and 82.4% (95% CI: 64.9-91.7%), respectively. Among the 34 patients, a pCR rate of 47.1% and an MPR rate of 70.6% were achieved. Patients achieving pCR or MPR had significantly better survival outcomes than did the nonresponders. In the subgroup analysis, a lower body mass index (BMI) (<25.0 kg/m2) and earlier disease stage II were associated with improved survival, although this was not statistically significant in all comparisons. Neoadjuvant or conversion chemoimmunotherapy followed by surgery demonstrates promising efficacy and survival benefits in patients with stage IIB-IIIB SCLC, with high pCR/MPR rates strongly predicting superior outcomes. These findings support the integration of immunotherapy into multimodal treatment strategies for patients with stage II-IIIB SCLC and warrant validation in larger randomized controlled trials.