Prognostic value of single nodal zone metastasis in non-small-cell lung cancer

Mediastinal nodal metastasis is related to poor prognosis in surgically resected non-small-cell lung cancer (NSCLC) and the prognosis becomes worse with an increasing number of nodal stations involved. However, intra-operative designation of each nodal station might be difficult and confusing because of the adjacency of the nodal stations, and this may cause inaccurate nodal staging. The new concept of a 'nodal zone' was proposed by the IASLC lung cancer staging project (IALC, International Association for the Study of Lung Cancer), and we investigated the impact of the 'nodal zone' on the survival of pathological N2 patients.

From a total of 1186 patients with NSCLC, who underwent surgical resection with curative intent, we analysed the survival data of 217 patients with ipsilateral mediastinal metastasis retrospectively.

The operative mortality rate was 1.4% (three patients) and median follow-up period was 35.4 months. The 5-year overall survival rate was 36.5% (median: 39.3 months; confidence interval (CI): 32.05-46.62). Median disease-free survival was 17.4 months (CI: 13.84-21.03). Overall and disease-free survival were better in the single-zone metastasis group than in the multiple zone group (median: 48.5 vs 33.4 months, p=0.001, CI: 32.05-46.62, and 20.4 vs 10.6 months, p<0.001, CI: 13.84-21.03). Among those of the single nodal zone metastasis group, no differences were found between the single and multiple nodal station metastasis groups in overall and disease-free survival.

Patients with single nodal zone metastasis showed favourable outcomes compared with the multiple zone metastasis group. Even though two or more nodal stations were involved, the outcome was favourable if the nodal stations involved were confined to a single nodal zone. In conclusion, patients with single nodal zone metastasis can benefit from surgical resection.