INTRODUCTION AND OBJECTIVESThe seventh edition of the TNM classification, together with undeniable advantages, has limitations. The International Association for the Study of Lung Cancer (IASLC) Staging Committee has designed an international prospective study to improve this classification. A group of thoracic surgeons and pulmonologists was established in the Spanish Society of Pulmonology and Thoracic Surgery (SEPAR) Oncology area, and created a registry of new lung cancer (LC) cases to participate in this project. The aim of this paper is to describe the main characteristics of the patients included.MATERIALS AND METHODSProspective, observational, multicentre, multiregional data collection (epidemiological, clinical, therapeutic and, especially, anatomical extension) study, according to the IASLC protocol, to analyse its prognostic value.RESULTSTwo thousand, four hundred and nineteen patients (83.6% men) from 28 hospitals were included. Ninety-six percent of the men and 54% of the women were smokers or ex-smokers. Chest/abdominal computed tomography (CT) scanning was performed in over 90% and positron emission tomography (PET)/CT scanning in 51.5% of cases. Among the 1035 patients who underwent surgery, 77% had early stages (ia to iib), and 61.6% of those treated using other methods had stage iv. Respiratory comorbidity was higher in men (47.9% versus 21.4%). The most common histological subtype was adenocarcinoma (34%), especially in non-smoking women (69.5%).CONCLUSIONSThe proportion of women and adenocarcinomas, as well as those resected at an early stage, increased among LC cases in Spain.