Prognostic factor and treatment strategy for clinical N1 non-small cell lung cancer

Objectives The aim of this study is to evaluate the surgical results of clinical N1 disease and to clarify the high-risk clinical N1 subgroup. Methods Between 1990 and 2012, 137 patients who were clinically diagnosed as having N1 disease were enrolled. Their medical records were reviewed to assess clinical characteristics, radiologic findings, pathologic results, postoperative outcomes, recurrence patterns, and survival. Logistic regression analysis was used to identify independent predictive factors for pathologic N2 upstaging. To determine which factors were significantly associated with survival, a multivariate analysis using a Cox proportional hazards model was performed. Results More cases were pathological N2 in adenocarcinoma than squamous cell carcinoma (p = 0.039). The overall survival rates at 5 years were 54.9%, 36.7% in group upper lobe, middle and lower lobe, respectively (p = 0.013). Logistic regression analyses revealed that #10 positive (p = 0.002, HR 4.625) and adenocarcinoma (p = 0.029, HR 1.544) were significant predictor of pathologic N2 disease. Multivariate analyses revealed that pathologic N2 (p = 0.007, HR 4.186), middle and lower lobe (p = 0.009, HR 2.045) and presence of #10 (p = 0.024, HR 1.871) were independent prognostic factors. Patients with upper lobe and absence of #10 showed a significantly higher 5-year survival rate than patients with middle and lower lobe and presence of #10 (62.1 vs 25.9%: p < 0.0001). Conclusions Among patients with cN1, pathological N2 disease, tumor in middle and lower lobe and clinical #10 lymph node positive were high-risk subgroup. Further analyses using larger numbers of patients with N1 disease from multiple centers are necessary.