LAUSR

OBJECTIVES Pathological N2 (pN2) involvement has a negative impact on prognosis in patients operated on due to non-small-cell lung cancer (NSCLC). pN2 disease may cause skip (pN0N2) or non-skip (pN1N2) metastases with pathological N1 (pN1) involvement. The effect of pN2 subgroups on prognosis is still controversial. We analysed the effect of pN1 disease and single-station pN2 disease subgroups on survival outcomes. METHODS The medical records of patients who underwent anatomical lung resection due to NSCLC at a single centre between January 2007 and January 2017 were prospectively collected and retrospectively analysed. Operative mortality, sublobar resection, Stage IV disease, incomplete resection and carcinoid tumour were considered exclusion criteria. After histopathological examination, the prognosis of patients with pN1, pN0N2 and pN1N2 was compared statistically. Univariable and multivariable analyses were made to define independent risk factors for overall survival rates. RESULTS The mean follow-up time for 358 patients with 228 pN1 disease (63.7%), 59 pN0N2 disease (16.5%) and 71 pN1N2 disease (19.8%) was 40.4 ± 30.4 months. Median and 5-year overall survival rates for pN1, pN0N2 and pN1N2 diseases were 73.6 months [95% confidence interval (CI) 55.5-91.7] and 54.1%, 60.3 months (95% CI 26.8-93.8) and 51.2%, 20.8 months (95% CI 16.1-25.5) and 21.5%, respectively. The survival CIs of pN1 and pN0N2 diseases were similar, and the survival rates of these 2 groups were significantly better than those with pN1N2 (P < 0.001, P = 0.001, respectively). In multivariable analysis, patients over the age of 60 [hazard ratio (HR) 2.13, P < 0.001], patients not receiving adjuvant therapy (HR 1.52, P = 0.01) and patients with pN1N2 disease (HR 2.91, P < 0.001) had a poor prognosis. CONCLUSIONS Advanced age, not receiving adjuvant therapy and having pN1N2 disease are negative prognostic factors in patients with nodal involvement who underwent curative resection due to NSCLC. The overall survival and recurrence-free survival rates of pN1 disease and single-station pN0N2 disease are similar, and they have significantly better survival rates than pN1N2 disease. Based on these results, surgical treatment may be considered an appropriate choice in patients with histopathologically diagnosed single-station skip-N2 disease.