Skip mediastinal nodal metastases in the IIIa/N2 non-small cell lung cancer

To study the incidence and characteristics of mediastinal nodal metastases without N1 nodal metastases (skip N2 metastases) in patients with resected pIII/A/N2 non-small cell lung cancer.

A total of 323 non-small cell lung cancer patients who underwent radical surgical resection with a systematic mediastinal nodal dissection in 4-year period (2000-2003) were retrospectively reviewed. The 85 patients (26%) at stage IIIA/N2 (pN2+) were grouped according to their skip metastases status. Patient data were statistically analyzed.

Skip N2 metastases were found in 21 patients (25%) without N1 nodal involvement. The postoperative survival for skip N2 disease was almost the same as that for pN2 disease with N1 nodal involvement. The incidence of N2 metastases seemed to be more frequent in adenocarcinoma patients (p < 0.005), but skip N2 metastases were significantly higher (p < 0.001) in squamous cell carcinoma patients. Although skip metastases involved more often upper mediastinal lymph nodes and one station level, the difference was not found statistically significant (p < 0.227). Complication rate showed no difference between analyzed groups of patients.

Sample mediastinal lymphadenectomy may not be appropriate in surgery for non-small cell lung cancer because skip metastases were found in 25% of patients without N1 nodal involvement.