We investigated patients with contemporarily staged and treated stage III-N2 NSCLC treated with induction chemotherapy and surgery with or without postoperative radiotherapy (PORT). We focused on survival and toxicity and investigated what additional PORT may offer in patients with ypN2 status or incomplete resection.

We identified 161 patients with pathologically proven, resectable stage III-N2 NSCLC from our prospective database who were treated between 1998 and 2012. Of these patients, 150 without progressive disease after chemotherapy underwent resection. Patients with ypN2 status or R1/2 resection received three-dimensional PORT (n = 70) to a dose of 50 to 66 Gy in 2-Gy fractions.

The mean follow-up time was 49 months. The 5-year overall survival (OS) rate was 35.1% in intention-to-treat analysis; relapse-free survival was 31.8%, the cumulative local recurrence (LR) rate was 50.9%, and the distant metastasis rate was 63.4%. The 5-year OS, relapse-free survival, and cumulative LR and distant metastasis rates were 32.0%, 32.9%, 47.0%, and 63.9% in the PORT group versus 38.1%, 30.7%, 54.1%, and 63.2% in the non-PORT group. These results were not significantly different, even though patients in the PORT group had worse prognostic features. Cardiac toxicity was higher in the non-PORT group (p = 0.02), but pulmonary toxicity was similar (p = 0.15). There was no difference between the two groups regarding dyspnea (p = 0.32), cough (p = 0.37), forced expiratory volume in 1 second (p = 0.30), and diffusing capacity of the lung for carbon monoxide (p = 0.61).

A similar outcome (OS, LR, and toxicity) was seen in both patient groups (PORT versus non-PORT group). Despite the limitations of this retrospective study, PORT can be both effective and safe for patients with stage III-N2 NSCLC with an R1/R2 resection or yN2 after induction chemotherapy and surgery.