Clinical prognostic factors in surgically treated stage IIIA-N2 non-small cell lung cancer: analysis of the literature.

There remains controversy on the prognostic value of several common clinical factors in NSCLC patients with resected N2-disease. The aim of this paper is to give a comprehensive overview of the available data on this issue. Literature data on surgically treated N2-NSCLC-patients from 1980-1995, peer reviewed and listed in Index Medicus, were analysed. Reported and calculated or estimated survival data were indexed. Eighteen series were selected: in 12 of them, direct comparisons between survival curves of subgroups are reported; six contained sufficient data to make comparisons of survivors at 5 years; three of them also made a multivariate Cox model. The analysis of prognostic factors in a single study was often hampered by the limited number of patients. Nonetheless, it could be concluded that patients with a clinical N0- or N1-status (so-called unforeseen N2) do better. There was no clear difference between patients undergoing lobectomy or pneumonectomy. There was strong evidence that N2-patients with a less advanced primary tumour (T-stage) have a better prognosis, and this is the case for all operable T-stages (T1 versus T2, T1 versus T3, T2 versus T3). Squamous cell type was a favourable prognostic factor, as was the presence of only one metastatic mediastinal lymph node station or absence of metastases to the subcarinal nodes. There was some evidence that the presence of extracapsular spread in metastatic MLN is an unfavourable finding. Stratification for these prognostic factors could help in the planning of future trials on combined modality treatment in N2-NSCLC.