Predictors of unexpected nodal upstaging in patients with cT1-3N0 non-small cell lung cancer (NSCLC) submitted to thoracoscopic lobectomy.

BACKGROUND: In the last decades, the use of video-assisted thoracoscopic surgery (VATS) lobectomy for the treatment of early stage non-small cell lung cancer is continuously growing. This is mainly due to the development of more advanced surgical devices, to the rising incidence of peripheral lung tumors and is also favored by the increased reliability of preoperative staging techniques. Despite this progress, postoperative unexpected nodal upstaging is still a relevant issue. Aim of this study is to identify possible predictors of unexpected nodal upstaging in patients affected by cT1-3N0 NSCLC submitted to VATS lobectomy.
METHODS: A total of 231 cases of cT1-3N0 patients submitted to thoracoscopic lobectomy at our centre between June 2012 and October 2016 were retrospectively reviewed. All data regarding clinical staging by means of computed tomography (CT) and positron-emission tomography (PET)/CT were collected and reviewed. The subsequent pathological staging has been analyzed, with special regards to the possible type of nodal involvement, and the number of pathological nodal stations.
RESULTS: Most of the patients included in this study were in a clinical stage cT1aN0, cT1bN0 (stage IA) and cT2aN0 (stage IB), 86 (37.2%) patients, 73 (31.6%) patients and 62 (26.8%) patients, respectively. Postoperative histopathological analysis showed that the most frequent tumor histotype was adenocarcinoma (192 patients, 83.1%). Thirty-eight (16.5%) patients had a nodal upstaging; among these, 17 (7.4%) patients had N2 disease (8 patients with isolated mediastinal nodal involvement, 9 patients with N1 + N2 disease) and 21 (9.1%) patients had an isolated hilar nodal involvement (N1). At bivariate analysis, the clinical T (cT)-parameter (P=0.023), the histotype (P=0.029) and the pathological T (pT)-parameter (P=0.003) were identified as statistically significant predictors of nodal upstaging. Concerning the type of nodal upstaging, the pT was found to be statistically significant (P=0.042). At bivariate analysis for the number of involved nodal stations, a statistical significance was highlighted for the parameters cT (P=0.030) and pT (P=0.027). With linear logistic regression, histology as well as pT reached statistical significance (P=0.0275 and P=0.0382, respectively). No correlation was found between nodal upstaging and the intensity of FDG uptake in the primary lung tumor or with the timing between PET and surgery.
CONCLUSIONS: There is a strong correlation between the clinical staging of the parameter T evaluated with CT and the possible unexpected nodal upstaging. The same correlation with nodal upstaging is found for pT. At equal clinical stage, in patients affected by adenocarcinoma of the lung the relative risk of having a postoperative unexpected nodal upstaging is almost 7 times higher than in patients with squamous cell carcinoma.