2202 - Disparities in the Efficacy of Different Treatment Modalities for Inoperable Non-Small Cell Lung Cancer in the Immune Era: A Retrospective, Real-World Study

X. R. Zhu¹, J. Liu¹, X. Cai², J. Liu¹, W. Feng², W. Yu², Q. Zhang², and X. Fu²; ¹Department of Radiation Oncology,Shanghai Chest Hospital ,Shanghai Jiaotong University School of Medicine, Shanghai, China, ²Department of Radiation Oncology, Shanghai Chest Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China

Purpose/Objective(s): In the immune era, chemo-immunotherapy (CIT) has shown exciting efficacy both in the neoadjuvant setting and in the first-line systemic treatment of non-small cell lung cancer (NSCLC). Here, we discussed the value of CIT in local-advanced NSCLC (LA-NSCLC) and explore the best treatment modalities for LA-NSCLC. Materials/

Methods: Consecutive patients with inoperable or refusing surgery stage II-III NSCLC receiving immunotherapy for the first-line systemic therapy from January 2018 to December 2022 were included. Survival outcomes, failure patterns and the best induction times were analyzed. The overall survival (OS), progression free survival (PFS) and local recurrence free survival (LRFS) were calculated using Kaplan-Meier methodology.
Results: 410 eligible cases were identified, 173 patients received thoracic radiotherapy before disease progression (RT group) and 237 patients received systemic CIT only without thoracic radiotherapy before disease progression (non-RT group). The median OS, PFS (mOS, mPFS) for RT group and non-RT group were 55.5 months, 21.3 months and 26.6 months, 14.1 months, respectively (P_OS < 0.0001, HR=0.49, 95% CI =0.34-0.70; P_PFS < 0.0001, HR=0.55, 95% CI =0.42-0.72). The local recurrence free survival (LRFS) of RT group is obviously better than non-RT group (P < 0.0001, HR=0.38, 95%CI 0.28-0.52), the median LRFS (mLRFS) of was 22.2 months and not reached in RT and non-RT groups. In addition, the mOS of CIT induction prior to concurrent chemo-radiotherapy (cCRT) group is better than the cCRT/sequential chemo-radiotherapy (sCRT) followed by ICI maintenance group (not reached VS 53.4 months, P=0.089, HR=0.31, 95% CI =0.13-0.78). Subgroup analysis revealed that patients with = 4 cycles CIT inductions prior to radiotherapy (RT) have a better prognosis than patients with > 4 cycles CIT inductions (P=0.036, HR=0.42, 95% CI =0.18-0.97). And patients who respond well to CIT induction prior to RT have a trend of better OS than those who respond poorly (P=0.08, HR=0.52, 95% CI =0.24-1.14). Exploring the optimal dose of RT showed that there was no significant difference in OS and PFS between 50Gy and 60Gy (P=0.141, HR=0.63, 95% CI =0.31-1.29).
Conclusion: In the immune era, RT remains indispensable for inoperable LA-NSCLC. The CIT induction of no more than 4 cycles before cCRT and followed by ICI consolidation therapy has achieved an exciting survival benefit for LA-NSCLC patients. And the best RT dose needs to be determined in a further study, 50Gy and 60Gy may not be different for selected patients.