A favorable population among clinical stage IIIA-N2 non-small cell lung cancer: The importance of the location of the primary tumor and involved nodes.

Abstract

7575 Background: The number of station of involved N2 nodes has been considered to be one of the most important prognostic factors for lung cancer. However most reports detailed with not clinical nodal status, but pathological nodal status. We investigated the relationship between prognosis and the location of the primary tumor and involved nodes. Methods: A retrospective study was conducted on 1257 patients with primary lung cancer, which was resected between 1996 and 2009. Among them, 79 patients (6.3%) had cN2, c-stage IIIA, pN2 and NSCLC. Mediastinal lymph node with a diameter of 10mm or more in the short axis was diagnosed as metastasis. We defined cN2α as only involvement of upper mediastinal lymph node (UMLN) in main tumor located on upper lobe or as that of lower mediastinal lymph node (LMLN) in main tumor located on lower lobe. And we did cN2β as involvement of LMLN in main tumor located on upper lobe with or without metastatic UMLN or as that of UMLN in main tumor located on lower lobe with or without metastatic LMLN. We analyzed preoperative clinical factors and investigated overall and disease-free survival. Results: The overall 5-year survival rate was 30.2% and median follow-up was 52.8 months. The disease-free 5-year survival rate was 22.2%. The differences in survival between cN2α and cN2β were statistically significant (29.5% vs. 0%, p-value=0.0007), whereas no significant differences was found between cN2 single station and multiple station (23.3% vs. 19.4%, p-value=0.1220). Multivariate analysis with cox’s hazard model disclosed that cN2α was independent good disease-free prognostic factor(HR: 0.426, 95%CI: 0.193-0.941). The sensitivity, specificity and positive predictive value for pN2 single station based on cN2 single station were 71.4%, 49.1% and 34.9% (p=0.1269). Conclusions: Clinical mediastinal lymph node status based on the location of the primary tumor and involved nodes was an important preoperative prognostic factor. Thus this factor should be taken into consideration for planning and evaluating clinical trials. Another fruit of the study was that clinical single nodal N2 was not always pathological single N2 disease.