Prognostic impact of the primary tumor location based on the hilar structures in non-small cell lung cancer with mediastinal lymph node metastasis

The status of mediastinal lymph node metastasis is one of the main factors determining the treatment strategy for non-small cell lung cancer (NSCLC), but the primary tumor location is not considered crucial in the tumor-node-metastasis (TMN) classification at present. The aim of this study was to estimate the prognostic value of the primary tumor location on the basis of the hilar structures in NSCLC with mediastinal lymph node metastasis. We retrospectively reviewed the cases of 337 consecutive patients who underwent surgical resection for NSCLC between 1995 and 2004, divided the pN2 NSCLC cases (n = 40) into central- and peripheral-type tumors according to the distance of the primary tumor from the first branch of the extrapulmonary bronchus, and compared the surgical outcomes between these tumor groups. Eighteen and twenty-two cases were classified as central- and peripheral-type tumors, respectively. The 5-year survival rate was significantly better for patients with central-type tumors than peripheral-type tumors (51.5% vs. 21.2%, P = 0.034). The location-specific prognostic tendency was noted irrespective of the presence (n = 13) or absence of skip metastasis. In a multivariate Cox analysis of the N2 NSCLC cases, the primary tumor location was a significant (P = 0.026) prognostic factor for overall survival. In conclusion, evaluation of the primary tumor location based on the hilar structures is useful to predict the prognosis in N2 NSCLC.