Significance of incidental N2 and other prognostic factors in N2 non small-cell lung cancer

Background: patients with IIIA-N2 non-small cell lung cancer represent a large and heterogeneous group. Some N2-related factors affecting prognosis have been identified. The present study investigated the prognostic factors of a group of N2 patients and gave an overview of available literature on this issue, especially considering N clinical status. Methods: the study comprised 187 patients. All the patients had a postoperative histologic diagnosis of mediastinal lymph node involvement and underwent complete resection.The following N2-related factors were investigated: N clinical status, number of metastatic lymph node levels, topography of lymph node involvement. Results: univariate analysis showed a significantly better prognosis for incidental N2, single station involvement and right-sided metastatic nodes (5-year survival respectively 35.4%, 28.3% and 33.7%). Survival analysis for number of metastatic levels stratified for N clinical status demonstrated the best prognosis for the cN0-1/single level subgroup (5-ys 38%). In the multivariate analysis only N clinical status was found as significant prognostic factor. Conclusions: our study has confirmed the relevance of N clinical status as a prognostic factor. The overview of the literature has shown that number of metastatic levels and subcarinal involvement may also be relevant prognostic factors. For cN0-1 patients surgery is mandatory. For cN2 patients correlation with other variables should be considered: when good prognostic factors are associated, surgery may be indicated but in a mulimodality setting; when negative factors are associated, results of surgery are poor and exclusive administration of radiation therapy should be evaluated. The development of an optimal procedure for preoperative staging is needed, to better detect N2-related prognostic factors.