1023 - Induction Immunochemotherapy followed by Definitive Radiotherapy in Patients with Limited-Stage Small Cell Lung Cancer: A Multicenter Study

05:40pm - 05:45pm ET

Room 258

Presenter(s)

Junxu Wen, MS - Shandong Cancer Hospital Affiliated to Shandong First Medical University, Jinan, Shandong

J. Wen¹, Q. Wang¹, X. Yu¹, Y. Liu¹, X. Yin¹, S. Li², H. Zhao³, Z. Huang⁴, Y. Chen¹, and X. Meng¹; ¹Department of Radiation Oncology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, China, ²Department of Oncology, Zibo Municipal Hospital, Zibo, China, ³Department of Radiation Oncology, Affiliated Hospital of Jining Medical University, Jining, China, ⁴Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China

Purpose/Objective(s): To compare the clinical outcomes of patients with limited-stage small cell lung cancer (LS-SCLC) who received induction immunochemotherapy followed by definitive radiotherapy to those who received standard chemoradiotherapy.

Materials/Methods: We retrospectively enrolled 568 patients with limited-stage small cell lung cancer (LS-SCLC) from four tertiary medical centers between January 2020 and December 2024. The patients were divided into two cohorts based on the treatment received: those who received induction immunochemotherapy followed by definitive radiotherapy (I-CRT cohort) and those who received chemoradiotherapy (CRT cohort). Survival and adverse event (AE) data were collected for further analysis, and subgroup analyses of the patients in the I-CRT group were conducted to explore the optimal induction treatment cycle.

Results: The I-CRT group demonstrated significantly improved progression-free survival (PFS) (mPFS: 15.53 vs. 10.31 months; HR: 0.544, 95% CI: 0.434–0.682; p < 0.001) and overall survival (OS) (mOS: 51.87 vs. 31.43 months; HR: 0.603, 95% CI: 0.439–0.828; p = 0.007) compared to the CRT group. The ORR was higher in the I-CRT group (79.2% vs. 69.4%), while the DCR was comparable (95.0% vs. 94.9%). In the CRT group, patients showed similar incidence of AEs (98.7% vs 97.0%) and grade 3-4 AEs (59.9% vs 63.4%) compared with patients in the I-CRT group. The incidence of pneumonitis (47.5% vs. 38.3%) and grade = 3 pneumonitis (9.9% vs. 5.5%) was higher in the I-CRT group. Subgroup analysis revealed that patients who received concurrent chemoradiotherapy and those who received twice-daily radiotherapy achieved significantly longer PFS and OS. Extending induction therapy to 4–6 cycles, compared with 1–3 cycles, was associated with no additional survival benefit and an increased incidence of pneumonia.

Conclusion: The induction of immunochemotherapy followed by definitive radiotherapy is feasible for LS-SCLC, with significantly improved survival and acceptable safety profiles. Further prospective trials are required to validate these findings.