[Skip metastasis to mediastinal lymph nodes: clinical significance and prognosis in stage III non-small cell lung cancer].

Objective: To analyze the significance and prognosis of skip metastasis to mediastinal lymph nodes in stage III non-small cell lung cancer (NSCLC).

Methods: The data of 65 patients who underwent resection for NSCLC with a pN(2)-stage were analyzed retrospectively. Twenty-one of these patients (32.3%), showing no metastatic involvement of hilar (N(1)) lymph nodes, were compared to the remaining 44 patients with infiltration of hilar nodes (N(1)) as well as N(2) nodes. Software SPSS 10.0 was used for statistical analysis.

Results: Multivariate analysis showed no statistically significant difference between the skip metastasis and the continuous N(2) group regarding sex, age, histology, location, and T-or M-status. In the skip metastasis group, mediastinal node metastasis was found in >or=2 region in 16 patients (36.4%) and in continuous N(2) group in 2 patients (9.5%, chi(2) = 8.571, P = 0.036). The 5-year survival rate of pN(2) patients with skip metastasis was 41% compared to 21% in patients with involvement of N(1) and N(2) nodes (P = 0.022 6), and the mean survival time was 44 months and 26 months respectively.

Conclusions: pN(2) patients with mediastinal lymph node skip metastasis have a more favorable prognosis compared to pN(2) patients with continuous infiltration of the regional lymph nodes. Skip metastasis is an independent prognostic factor for survival. Skip metastasis may represent a subgroup of pN(2) classification.