Validation of pN2 sub-classifications in patients with pathological stage IIIA N2 non-small cell lung cancer

Optimal surgical treatment for patients with stage IIIA N2 non-small cell lung cancer (NSCLC) remains a matter of debate, because of the outcomes. The outcomes may be affected from variations in patterns of lymph node metastasis. As the patterns of lymph node sub-classifications, multiple station metastases of mediastinal lymph nodes (MN2), highest metastasis of the mediastinal lymph nodes (HM), distribution of metastatic nodes (skip N2 or non-skip N2), and clinical (c-) N factor have been cited. We investigated these factors for patients with pathological stage IIIA (pIIIA) N2 NSCLC. We reviewed 121 consecutive patients with pIIIA N2 who underwent complete resection. Age, gender, tumor laterality, histology, lobe location of the tumor, c-T factor, pathological (p-) T factor, c-N factor, MN2, HM and skip N2 condition were used as prognostic variables. Overall five-year survival rate was 41.8%. Based on log-rank testing, c-T factor (P = 0.022), p-T factor (P = 0.0002), c-N factor (P = 0.009), HM (P = 0.019) and skip N2 (P = 0.030) were identified as significantly prognostic. Using these variables, p-T factor, c-N factor and skip N2 showed significance and independence on Cox multivariate analysis. The sub-classification of lymph node metastasis in patients with p-stage IIIA N2 NSCLC has clinical implications for the prognosis.