210 - Analysis of Progressive Patterns after First-Line Chemoimmunotherapy with or without Thoracic Radiotherapy in Extensive-Stage Small Cell Lung Cancer
Presenter(s)
J. Feng1,2, X. Fan1, B. Li1, T. Dong3, C. Jiang4, and L. Wang5; 1Department of Radiation Oncology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, Shandong, China, 2School of Clinical Medicine, Shandong Second Medical University,, Weifang, Shandong, China, 3Department of Obstetrics and Gynecology, Qilu Hospital of Shandong University, Jinan, Shandong, China, 4Department of Otorhinolaryngology & Head and Neck Surgery, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China, 5Department of Radiation Oncology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, China, Jinan, Shandong, China
Purpose/Objective(s): Chemoimmunotherapy remains the first-line standard treatment for extensive-stage small-cell lung cancer (ES-SCLC). However, nearly all patients eventually experience progression following first-line treatment, with prognosis varying significantly depending on the patterns of progression. The addition of thoracic radiotherapy (TRT) to first-line chemoimmunotherapy has demonstrated improved survival benefit in ES-SCLC patients. Nevertheless, the impact of TRT on the patterns of progression remains unclear. This study aimed to investigate the differences in progressive patterns between patients receiving TRT and those who did not, providing critical insights to guide subsequent treatment decisions and improve treatment outcomes.
Materials/Methods: ES-SCLC patients receiving first-line chemoimmunotherapy were enrolled from three medical centers from January 2020 to December 2024. Baseline characteristics, treatment strategies, progressive patterns and survival data were collected. The progressive patterns were categorized into different groups based on the site and numbers of lesions, including progression occurred intrathoracic or extrathoracic or both, progression of existing lesions or development of new lesions or both, oligo-progression or multi-progression. Overall survival (OS) and progression-free survival (PFS) were assessed using the Kaplan–Meier method and compared through log-rank tests. Chi-square tests and Fishers’ exact tests were used to compare the progressive patterns between groups.
Results: A total of 320 ES-SCLC patients receiving first-line chemoimmunotherapy were included in this study. By the data cut-off date (December 2024), 252 (79%) patients had developed disease progression, The predominant progressive patterns involved the brain, lung and regional lymph nodes. Among 252 patients with disease progression, those with only intrathoracic progression (mOS: 21.9 vs. 21.1 vs.13.8months, p=0.028), development of new lesions (mOS: 23.6 vs. 20.0 vs.15.5months, p=0.037), or oligo-progression (mOS: 24.3 vs. 15.9 months, p<0.001) demonstrated significantly better overall survival. The addition of TRT significantly reduced the occurrence rate of intrathoracic progression (30.15% vs. 66.38%, p<0.001) and progression of existing lesions (32.35% vs. 44.83%, p<0.001), but not oligo- or multi-progression. In terms of time to progression, TRT significantly extended the time to intrathoracic progression (9.80 vs. 6.57 months, p=0.047), development of new lesions (9.60 vs. 5.70 months, p=0.019), and multi-progression (8.50 vs. 5.98 months, p<0.001).
Conclusion: TRT could not only reduces the occurrence rate of intrathoracic progression and progression of existing lesion, but also delays their onset. Although TRT failed to reduce the risk of multi-progression, it significantly prolonged the time to its onset.