2095 - Impact of Locoregional Recurrence vs. Distant Metastasis on Overall Survival in Patients with Non-Small Cell Lung Cancer after Surgery: A Secondary Analysis of a Randomized Controlled Trial

Z. Ma¹, and Z. Hui²; ¹Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China, ²Department of VIP Medical Services, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China

Purpose/Objective(s): Postoperative radiation therapy (PORT) has been demonstrated to reduce the incidence of locoregional recurrence (LR) in patients with non-small cell lung cancer (NSCLC) after surgery. Despite this, the therapeutic advantage of PORT has not been translated into an overall survival (OS) benefit according to findings from two recent randomized controlled trials, albeit an enhancement in locoregional-free survival was observed. We aimed to dissect the differential roles of LR and distant metastasis (DM) on OS in patients with NSCLC after surgery. Materials/

Methods: Patients from a randomized controlled trial were enrolled. The inclusion criterion included patients with histologically proven pN2 NSCLC who underwent complete resection and chemotherapy. Patients were analyzed per protocol. A dynamic prediction model was developed to evaluate the impact of LR and DM on OS. The endpoint was OS. Age, sex, smoking history, histology, Karnofsky Performance Status, tumor side, pT stage, and positive lymph node were baseline factors, whereas LR and DM status were time-dependent covariates.
Results: 364 patients were eligible, with 214 in the non-PORT group and 150 in the PORT group. The median follow-up period was 49.0 months (IQR, 45.0-54.0). DM showed a significant impact on OS (OR, 4.94; CI, 2.65-9.19; P<.001) while LR did not (OR, 1.62; CI, 0.81-3.25; P=0.175). Multivariate Cox analysis identified the pT stage, positive lymph nodes, and histology as variables correlated with DM. A nomogram was developed to estimate the risk of DM. PORT did not significantly enhance OS in low-risk or high-risk subgroups, but in the medium-risk subgroup (HR, 0.46, 95% CI, 0.14-1.48, P= 0.19).
Conclusion: DM significantly impacted OS for patients with NSCLC after surgery, while LR did not when DM emerged as the dominant failure pattern, emphasizing the need for more effective control of DM. PORT was beneficial for patients with a medium risk of DM.