Postoperative chemoradiotherapy is superior to postoperative chemotherapy alone in squamous cell lung cancer patients with limited N2 lymph node metastasis

BACKGROUND: The aim of the present study was to assess the efficacy of postoperative chemoradiotherapy (POCRT) following surgery in non-small-cell lung cancer patients with N2 lymph node metastasis (N2-NSCLC). METHODS: The clinical data of patients with N2-NSCLC treated with POCRT or postoperative chemotherapy (pCT) alone were retrospectively collected and reviewed. The overall survival (OS) rates were analyzed utilizing the Kaplan-Meier method and compared by the log-rank test. Cox regression analysis was used to determine factors significantly associated with survival. Propensity score matching (PSM) analysis was used to compensate for differences in baseline characteristics and OS was compared after matching. RESULTS: Between 2004 and 2014, a total of 175 patients fulfilled the inclusion criteria, 60 of whom were treated with POCRT, while 115 were administered pCT. The 1, 3 and 5-year OS rates in the POCRT and pCT groups were 98.3 vs. 86.1%, 71.7 vs. 53.0% and 45.7 vs. 39.0%, respectively (P = 0.019). Compared with pCT, POCRT improved OS in patients with squamous cell subtype (P = 0.010), no lymphovascular invasion (P = 0.006), pN2a (P = 0.006) or total number of metastatic lymph nodes ≤7 (P = 0.016). After PSM, these survival differences between POCRT and pCT remained significant in patients with squamous cell lung cancer (P = 0.010). CONCLUSIONS: POCRT following complete resection may be beneficial for patients with squamous cell lung cancer, particularly those with limited nodal involvement.