Role of postoperative radiotherapy after curative resection and adjuvant chemotherapy for patients with pathological stage N2 non-small-cell lung cancer: a propensity score matching analysis.

BACKGROUND: The objective of this study was to evaluate the role of postoperative radiotherapy (PORT) in the setting of adjuvant chemotherapy for pathological stage N2 (pN2) non-small-cell lung cancer (NSCLC).

MATERIALS AND METHODS: A retrospective review of 219 consecutive pN2 NSCLC patients who underwent curative surgery followed by adjuvant chemotherapy was performed. Forty-one patients additionally received PORT. Propensity scores for PORT receipt were individually calculated and used for matching to compare the outcome between patients who did (+) and did not (-) receive PORT. One hundred eleven patients in the PORT (-) group and 38 patients in PORT (+) group were matched. Clinical and pathologic characteristics were well-balanced.

RESULTS: The median follow-up duration was 48 months. In the matched patients, PORT resulted in a significantly lower crude locoregional relapse (43.2% vs. 23.7%; P = .032). Also, PORT was associated with improved locoregional control (LRC) rate (5-year LRC 63.7% vs. 48.6%; P = .036), but not distant metastasis-free survival, disease-free survival (DFS), and overall survival. An exploratory subgroup analysis suggested a potential DFS benefit of PORT in patients with multiple station mediastinal lymph node metastases (5-year DFS, 43.2% vs. 16.6%; P = .037) and squamous cell carcinoma histology (5-year DFS, 70.1% vs. 23.3%; P = .011).

CONCLUSIONS: Even in the setting of adjuvant chemotherapy, PORT significantly increased LRC for patients with curatively resected pN2 NSCLC. Some subgroups appear to benefit from PORT in terms of DFS and LRC. Individualized strategies based on risk factors might be considered.