2412 - Screening of the Population Benefiting from Postoperative Radiotherapy in Resectable Stage III-N2 NSCLC Patients Receiving Neoadjuvant Chemoimmunotherapy
Presenter(s)
M. Li1, K. Wang2, J. Zhao1, B. Huang1, X. Wang2, J. Zhu1, G. Cai1, and X. Meng1; 1Department of Radiation Oncology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, China, 2School of Clinical Medicine, Shandong Second Medical University, Weifang, China
Purpose/Objective(s): The rise of immunotherapy has reshaped the treatment paradigm for resectable NSCLC, establishing neoadjuvant chemoimmunotherapy as the new standard of care. However, the benefit of postoperative radiotherapy (RT) for stage N2 NSCLC patients who undergo neoadjuvant chemoimmunotherapy remains unclear. Therefore, this study aims to explore the population that may benefit from postoperative RT in stage N2 NSCLC patients treated with neoadjuvant chemoimmunotherapy.
Materials/Methods: We retrospectively enrolled stage III-N2 NSCLC patients who received neoadjuvant chemoimmunotherapy at Shandong Cancer Hospital from 2018 to 2023. Patients were grouped by postoperative RT. The Clinical Target Volume (CTV) includes the ipsilateral hilar region of the lung (including the resection stump), the ipsilateral mediastinum, and the subcarinal area. The median prescription dose is 50 Gy. Subgroup analysis includes the number of lymph nodes dissected, the number of lymph node stations dissected, the number of metastatic lymph node, the number of metastatic lymph node stations, the pathological response of the primary lesion and metastatic lymph nodes, tumor differentiation, and histological high-risk factors. Event-free survival (EFS) and overall survival (OS) were evaluated using the Kaplan-Meier method, and the log-rank test was used for group differences.
Results: With a median follow-up of 32.9 months, a total of 147 patients were included in this study, with 37 in the RT group and 110 in the non-RT group. After 1:1 propensity-score matching, 37 patients in each group were matched. There were no significant differences in EFS and OS between the RT group and the non-RT group. The locoregional recurrence-free survival for the RT group was significantly better than that of the non-RT group. Subgroup analysis showed that in patients whose metastatic lymph nodes didn’t achieve pathological complete response (pCR), those who received postoperative RT exhibited significantly improved EFS compared to those who did not. But for patients whose metastatic lymph nodes achieved pCR, there is no difference in either EFS or OS between those who received postoperative RT and those who did not.
Conclusion: For resectable Stage III-N2 NSCLC patients receiving neoadjuvant chemoimmunotherapy, postoperative RT can reduce intrathoracic progression but does not confer EFS and OS benefits. However, among patients whose metastatic lymph nodes didn’t achieve pCR may derive EFS benefits from postoperative RT. Future large-scale prospective studies are needed to confirm these findings.