Resected pN1 non-small cell lung cancer: recurrence patterns and nodal risk factors may suggest selection criteria for post-operative radiotherapy

To describe the pattern of recurrence in resected pN1 non-small cell lung cancer (NSCLC) and to identify factors predicting an increased risk of locoregional recurrence (LR) or distant metastasis (DM) to define a selected population who may benefit from postoperative radiotherapy (PORT). 285 patients with resected pN1 NSCLC were identified. Patients with positive surgical margins, undergoing neoadjuvant treatment or PORT, were excluded. LR was defined as first event of recurrence at the surgical bed, ipsilateral hilum or mediastinum, and other sites were considered as DM. Kaplan-Meier actuarial estimates of overall survival (OS), progression-free survival (PFS), freedom from LR (FFLR) and freedom from DM (FFDM) in different subgroups were compared with the log-rank test. Multivariate analysis was calculated. 202 patients met the inclusion criteria, 24 % received adjuvant chemotherapy. The median follow-up was 39 months. The total number of recurrences was 118 (64.4 %): 44 (24 %) and 74 (40.4 %) for LR and DM, respectively. Five-year OS and PFS rates were 39.2 and 33.3 %, respectively. Extra capsular extension (ECE) (RR 2.10, p = 0.01) and lymph nodal ratio (LNR) > 0:15 (RR 1.68, p = 0.015) were associated with a worse PFS. ECE and LNR > 0.15 were significantly related to a worst FFLR (RR 3.04 and 4.42, respectively), and adenocarcinoma to an unfavorable FFDM (RR 1.97, p = 0.013). Nodal factors as high LNR and ECE can predict an increased risk of worse FFLR and PFS. Prospective data on selected patients, treated with modern radiotherapy techniques, need to be collected to re-evaluate the role of radiotherapy.