CT uptake and therefore guide preoperative staging and intraoperative lymphadenectomy.

J Thorac Dis 2017;9(9):2835-2838 jtd.amegroups. com Lymph node status is currently one of the most important prognostic factors for the management of non-small cell lung cancer (NSCLC). According to the current guidelines (1), in case of clinical N2 or N3, patients are not candidate to surgery and they are referred to neoadjuvant or definitive chemotherapy and/or radiotherapy, meanwhile in case of clinical N0/N1 surgery is the treatment of choice. Nonetheless, the definition of both N1 and N2 is still based only on merely anatomical criteria and they therefore enclose a wide range of different pathological situations with different prognosis (2). Moreover, the extent of lymphnode dissection has been debated, but to date no strong evidences are available to support one technique or another. The European Society of Thoracic Surgeons (ESTS) has proposed the current standard for systematic lymphadenectomy in case of lung resection for NSCLC (3), which encompass to harvest lymph-nodes from at least three mediastinal stations, always including sub-carinal lymphnodes. Nevertheless, some less extensive techniques for lymphadenectomy have been proposed, namely lymph node sampling, which accounts for resection of only macroscopic and focal lymph nodes, and lobe-specific lymphadenectomy, which is the resection of only stations which are considered as the natural drain for that lobe (4,5). Bille and his colleagues (6) retrospectively analysed a wide cohort of clinical early stage NSCLC treated with lobectomy, segmentectomy or wedge resection and systematic mediastinal lymphadenectomy in a single centre focusing on the pattern of lymphatic spread and longterm outcomes. They report 146 cases among 1,667 (9%) of occult N2, of which 16% had a metastasis in a “nonlobe specific station”. Authors conclude that systematic lymphadenectomy should be carried out also in patients who have a clinical N0 in order to avoid an understaging and a R1 resection. Similar conclusions were drawn by Riquet (7), who found an incidence of pN2 as high as 7.7% on the right side and 8.9% on the left side in patients with a clinical node negative early stage NSCLC of which 14.5% and 27.8% respectively did not follow lobe specific lymphatic drainage. In particular, accordingly to Asamura (8), the authors highlighted a particular propensity of left lower lobe tumors to metastasize to the left lower paratracheal station (4L), which is not considered to be lobe specific. Incidence of unexpected N2 might be reduced by a careful preoperative staging which may include invasive procedures such as EBUS, EUS or mediastinoscopy; Obiols (9) reports his institution’s experience finding a persistent 5% rate of unknown N2 after mediastinoscopy, but these patients had a longer 5-year survival compared to other reports of occult N2. Nevertheless, an American prospective study (10) concludes that invasive staging procedures for clinical node negative patients should be avoided as poorly costeffective, even though the authors suggested the possibility to understand the possible neoplastic lymph node spreading based on tumor localization, histological features and PETEditorial