Materials and Methods: Patients who underwent lung resection in our hospital between September 2014 and April 2016 were retrospectively included in this study. Resected specimens were dissected in the operating room by the surgeon before being put into formaldehyde solution. Patients were divided into three groups: with a single positive N1 node (Group 1), with multiple positive N1 nodes (Group 2), and with single or multiple positive N1 nodes and incidentally positive N2 nodes (Group 3).

Results: Fifty patients were included (46 males, 4 females). Univariate analysis showed significant correlation between N1 positivity and left-sided tumor, left central mass, squamous cell carcinoma, maximum standardized uptake (SUVmax) on positron emission tomography (PET/CT), pneumonectomy, and tumor size (p < 0.05). Logistic regression showed that the risk of N1 involvement was higher for squamous cell carcinoma compared to adenocarcinoma in all three groups.

Conclusions: Left central mass, squamous cell carcinoma, SUVmax ≥ 10, uptake in hilar lymph nodes on PET-CT, and tumor diameter > 3.5 cm correlated with single or multiple positive N1 nodes in our study. Specimen dissection in patients with such preoperative findings could improve the accuracy of pathological nodal staging, thus refining the assessment of prognosis and selection of patients who would benefit from adjuvant therapy. Keywords : lymph node dissection, lymphatic metastasis, non-small-cell lung carcinoma, surgical pathology, thoracic surgery