Postoperative Radiotherapy for Surgically Resected ypN2 Non-Small Cell Lung Cancer

The role of postoperative radiotherapy (PORT) in patients with clinical stage III-N2 (cIII-N2) non-small cell lung cancer (NSCLC) treated with induction chemotherapy and surgical resection with persistent ypN2 disease is not well established.

We retrospectively reviewed a prospectively maintained database for patients with cIII-N2 NSCLC who underwent induction chemotherapy followed by resection (2004-2016). Exclusion criteria included induction radiotherapy, non-biopsy-confirmed cN2 disease, incomplete resection, ypN0/1, and nonanatomic resection. The primary outcome was locoregional recurrence (LR); secondary outcomes were disease-free survival (DFS), lung cancer-specific death (LCSD), and overall survival (OS). Associations between variables and outcomes were assessed using Fine and Gray competing risk regression for LR/LCSD and Cox proportional hazard models for survival.

Of the 501 patients identified with cIII-N2 disease, 99 met the inclusion criteria. Median follow-up was 25 months (range, 3-137 months). Sixty-nine patients (70%) received PORT. Sixty (61%) developed a recurrence: 3 (5%) with an initial isolated LR and 57 (95%) with an initial distant recurrence. On multivariable analysis, PORT was not associated with LR (HR, 0.51 [95% CI, 0.22-1.21], p = 0.13). PORT was also not associated with DFS (p = 0.6) or LCSD (p = 0.1). PORT was associated with improved 3-year OS (55% [95% CI, 42%-71%]) versus the no-PORT group (50% [95% CI, 34%-74%]) (p = 0.04).

PORT is not independently associated with decreased LR or improved DFS/LCSD in this patient population. Given that the predominant failure pattern was distant recurrence, future clinical trials should focus on adjuvant systemic therapies, which may decrease distant recurrences in ypN2 patients.