Early Stage Non–Small-Cell Lung Cancer: Surgical Implications of the New Adenocarcinoma Classification

Abstract

To the Editor: We read with great interest the article by Osarogiagbon et al.1Osarogiagbon RU Allen JW Farooq A Wu JT Objective review of mediastinal lymph node examination in a lung cancer resection cohort.J Thorac Oncol. 2012; 7: 390-396Abstract Full Text Full Text PDF PubMed Scopus (58) Google Scholar highlighting the role of accurate mediastinal staging of resected non–small-cell lung cancer (NSCLC). New surgical approaches have been proposed in the recent years in case of cT1a, N0, or N1 less than hilar NSCLC. These include sublobar resection, video-assisted lobectomy, and robotic lobectomy. Moreover, new lymphadenectomy approaches have been proposed and adopted in early-stage NSCLC, including lobe-specific lymphadenectomy in cT1a as proposed in Europe by the European Society of Thoracic Surgeons (ESTS) guidelines,2Lardinois D De Leyn P Van Schil P et al.ESTS guidelines for intraoperative lymph node staging in non-small cell lung cancer.Eur J Cardiothorac Surg. 2006; 30: 787-792Crossref PubMed Scopus (503) Google Scholar and lymph node sampling according to the American College of Surgery Oncology Group Trial proposed by Darling et al.3Darling GE Allen MS Decker PA et al.Randomized trial of mediastinal lymph node sampling versus complete lymphadenectomy during pulmonary resection in the patient with N0 or N1 (less than hilar) non-small cell carcinoma: results of the American College of Surgery Oncology Group Z0030 Trial.J Thorac Cardiovasc Surg. 2011; 141: 662-670Abstract Full Text Full Text PDF PubMed Scopus (542) Google Scholar In early-stage NSCLC (clinically N0 with pathological nodule size ⩽10 mm), systematic nodal dissection seems to be universally unnecessary as the risk of nodal involvement is very low. In this scenario, the patients selection for sublobar or lobar resection and the role of mediastinal sampling versus radical lymphadenectomy is actually crucial because of the increasing proportion of lung cancer screening programs, and because of the new implications of the International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society revision of the adenocarcinoma classification.4Travis WD Brambilla E Noguchi M American Thoracic Society et al.International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society: international multidisciplinary classification of lung adenocarcinoma: executive summary.Proc Am Thorac Soc. 2011; 8: 381-385Crossref PubMed Scopus (418) Google Scholar These could have profound implications for thoracic surgeons. Indeed, as reported by Van Schill et al.5Van Schil PE Asamura H Rusch VW Mitsudomi T Tsuboi M Brambilla E Travis WD Surgical implications of the new IASLC/ATS/ERS adenocarcinoma classification.Eur Respir J. 2012 Feb; 39 (Epub 2011 Aug 4): 478-486Crossref PubMed Scopus (145) Google Scholar the new categories, adenocarcinoma in situ (AIS) and minimally invasive adenocarcinoma (MIA) less than 3 cm, should have 100% 5-year disease-free survival after sublobar resection and mediastinal sampling. The definitions of AIS and MIA seem to overlap almost precisely with the kinds of small, less-aggressive tumors identified by the clinical evidence, like ground-glass opacity (GGO). We completely agree with the Osarogiagbon et al.that most resections had suboptimal mediastinal lymph node examination up to 40%, according to Surveillance, Epidemiology and End Results and National Non-Communicable Diseases Program data sets, but maybe in a cT1 GGO-adenocarcinoma subset, the complete mediastinal lymph node examination (CMLE) may not be necessary. The analysis of the correlation among GGO, AIS/MIA histology, and limited resection without CMLE could strengthen the surgical implications of the new adenocarcinoma classification. In the near future, the role of the multidisciplinary team will be crucial in defining pre- and intraoperative early-stage AIS or MIA, and in tailoring and planning oncologically valid limited resections without CMLE.