Prognostic evaluation of nodal staging based on the new IASLC lymph node map for lung cancer.

BACKGROUND

The purpose of this study was to evaluate the new lymph node map proposed by the International Association for the Study of Lung Cancer (IASLC) from the point of prognosis, and to identify the significant prognostic factors in each pathological N stage.

METHODS

We reviewed 647 consecutive patients with surgically resected non-small cell lung cancers. Survival was analyzed according to N stage and three prognostic subgroups: N1a (single N1 zone), N1b (multiple N1 zones) or N2a (single N2 zone), and N2b (multiple N2 zones). The following prognostic factors were evaluated for each N stage: location of involved zones, number of involved lymph nodes, stations and zones, and the presence of skip metastases.

RESULTS

(1) The survival curves showed a stepwise deterioration as the N stage increased. (2) No significant difference was observed in survival between the different locations of involved zones in each N stage. (3) In N2 patients, the presence of skip metastases was a significant prognostic factor in multivariate analysis.

CONCLUSIONS

The proposed IASLC map is valid for prognostic stratification. The prognostic impact of the presence of skip metastases on N2 disease should therefore be taken into consideration when carrying out the forthcoming revision of the TNM staging system.