Background: The role for postoperative radiation therapy (PORT) for patients with non–small-cell lung cancer (NSCLC) with mediastinal lymph node (LN) involvement (pN2 disease) is controversial. We performed a SEER analysis comparing surgery alone with PORT among patients with pN2 NSCLC. As we await the final results of the LUNG ART trial, a subset of patients with a high LN positive to sampled (LPR) ratio may benefit from PORT.
Patients/methods: Patients with pN2 NSCLC, ranging from 1989-2016, were assessed from the Surveillance, Epidemiology and End Results (SEER) database. A propensity score (PS)-matched, inverse probability of treatment weighting (IPTW) analysis was conducted with multiple imputation with chained equations used for missing LN data.
Results: A total of 9,423 patients were included in this study (N=4,950 surgery alone; N=4,473 PORT). After adjusting for selection bias with IPTW; there was no improvement in overall survival (OS) (HR 0.99, P=0.76). However, a subset of patients with LPR = 50% did have improved OS (HR, 0.90; P=0.01).
Conclusion: In a large retrospective SEER analysis, PORT is not associated with an OS improvement or detriment among patients with pN2 NSCLC. Indeed, preliminary results from the LUNG ART trial identified no difference in disease free survival (DFS) with hazard ratio (HR) of 0.85 (p=0.16) or in OS. We look forward to the final results of the LUNG ART trial to better delineate which subgroups of patients may benefit from PORT. Our study suggests that a high LPR may be a potential indication for PORT.
Lung cancer; Postoperative radiation therapy; Adjuvant therapy; pN2 NSCLC; SEER