Skip N2 Metastasis in Pulmonary Adenocarcinoma: Good Prognosis Similar to N1 Disease

We analyzed the prognosis of lung adenocarcinoma to elucidate the influence of skip N2 metastasis. Skip N2 disease has a similar prognosis to N1 disease and is significantly better than that of non-skip N2 disease. Skip N2 has a prognostic advantage in patients with the acinar-predominant subtype. Pathological subtypes of lung adenocarcinoma may influence subgroup of patients with lymph node metastasis. Introduction: The prognostic effect and mechanism of skip N2 lung cancer remain unclear. Our study aimed to elucidate the influence of skip N2 on overall survival (OS) and disease-free survival (DFS) compared with N1 and non-skip N2 in patients with lung adenocarcinoma. Patients and Methods: Patients with lung adenocarcinoma and lymph node involvement between May 2011 and December 2015 were retrospectively analyzed. The outcomes of skip N2 patients were compared with N1 and non-skip N2 patients. Prognosis was further investigated according to the N status in different adenocarcinoma subtypes. Univariate and multivariate analyses were carried out to define independent risk factors for OS and DFS. Results: A total of 456 patients with lung adenocarcinoma, 169 with N1 disease, 81 with skip N2 disease, and 206 with non-skip N2 disease, were enrolled in this study. All tumors were invasive adenocarcinoma, and the predominant subtypes were acinar in 252, papillary in 42, solid in 119, micropapillary in 20, and invasive mucinous adenocarcinoma in 23 patients. The DFS and OS of N1 and skip N2 diseases were similar and significantly better than those of patients with non-skip N2 disease. The prognosis according to lymph node status was significantly different in acinar-predominant subtypes in terms of both OS and DFS. Conclusions: Skip N2 disease has a similar prognosis to N1 disease and is significantly better than that of non-skip N2 disease in relation to OS and DFS. Skip N2 has a prognostic advantage in patients with the acinar-predominant subtype. (C) 2020 Elsevier Inc. All rights reserved.