Postoperative Radiotherapy for Resected Stage IIIA–N2 Non-small-cell Lung Cancer: a Review of Outcomes

Objective: To review the outcomes of postoperative radiotherapy (PORT) using three-dimensional conformal techniques in patients with resected pathological N2 (pN2) non-small-cell lung cancer (NSCLC). Methods: Consecutive patients who underwent PORT for resected pN2 NSCLC were retrospectively reviewed. Adjuvant chemotherapy was given before PORT. Locoregional and systemic recurrences, disease-free survival (DFS), and overall survival (OS) were estimated using the Kaplan-Meier method. Factors associated with DFS and OS were determined using the log-rank test. Results: Eight men and seven women aged 38 to 76 (median, 65) years were included. All had stage IIIA cancer and underwent lobectomy. 12 and three patients had single and multiple mediastinal lymph node station involvement, respectively. The median numbers of resected lymph nodes and lymph node stations were 6 and 4, respectively. Only five patients underwent systematic nodal dissection or sampling. 13 patients underwent adjuvant chemotherapy. The median follow-up period was 31.9 months. Actuarial locoregional control was 100% at 1 year, 92.4% at 2 years, and 82.0% at 3 years. Ten patients had recurrence; all had distant metastases as the first failure event. The median time to recurrence was 12.6 months. DFS was 66.5% at 1 year, 46.5% at 2 years, and 40.0% at 3 years; the median DFS was 14.9 months. OS was 93.5% at 1 year, 66.5% at 2 years, and 51.5% at 3 years; the median OS was 42.4 months. There were nine deaths; eight were cancer-related and one was of unknown cause. Multiple pN2 lymph node station involvement was the only variable that was significant for both DFS and OS. Compared with patients with single pN2 lymph node station involvement, patients with multiple pN2 lymph node station involvement had shorter median DFS (10.9 months vs. 29.2 months, p = 0.008) and median OS (12.1 months vs. 54.1 months, p = 0.003). No patient had grade 3 or above toxicities. Conclusion: PORT using modern techniques and dose fractionation for patients with resected pN2 NSCLC was well tolerated and resulted in a high locoregional control rate, but the rate of distant metastasis remained high. Patients with multiple pN2 lymph node station involvement had worse survival. Author affiliation(s): YT Lam, FMY Lim, ACK Cheng: Department of Oncology, Princess Margaret Hospital, Laichikok, Hong Kong M Tong: Department of Clinical Oncology, Prince of Wales Hospital, Shatin, Hong Kong