Currently, 85% of cases are diagnosed at a late stage, which considerably reduces the rate of cure. Lung cancer is the most common carcinoma in western countries and the one that causes most deaths; more than those caused by breast cancer, cancer of the colon and prostate cancer put together. Tobacco is the main cause of this illness, with the risk of it arising persisting even twenty years after giving up smoking. In general this pathology is diagnosed on its symptoms appearing, indicating that it is at an advanced stage and with poor prognosis. In fact, using traditional techniques, only 15% of cases are detected at an early stage; this is why it is essential to find tools for early detection which will guarantee the curing of the illness. The research by the Lung Service at the Navarre University Hospital used thoracic CAT to periodically analyse persons at high risk of developing lung cancer, i.e. over-forties who have smoked at least one packet a day over ten years. The study is part of the ELCAP (Early Lung Cancer Action Program), international project in which centres from the United States, Europe, Japan, China and Israel participated. Results The research proved the efficacy of this imaging technique for the early-stage detection of lung cancer. The published results correspond to the first 1000 persons who took part in the project at the University Hospital. Concretely, cancer was detected in 14 individuals, thirteen at stage 1, the earliest and most curable stage. This work confirmed the conclusions obtained by ELCAP from more than 30,000 persons. Despite the direct link between tobacco and lung cancer, only 15% of smokers develop the disease. Thus, it is fundamental to find any risk factors that predispose having this pathology. This study discovered that there was a greater risk amongst asymptomatic smokers than amongst those who were diagnosed with obstructive pulmonary disease with spirometry. In any case, it is essential to continue with these lines of research aimed at identifying the population at high risk with precision. Specifically, a priority line of investigation at the University Hospital and the CIMA Centre at Navarre University involves the study of biomolecular techniques and their combination with radiological tests that help in the early detection of lung cancer. Once the first results are published, the project will continue to review, by means of CAT, those patients who have not developed the illness. What is wanted is a better definition of the use of this technique in order to judge its efficacy in the detection of new cancers amongst this population at risk. Moreover, the effect of this monitoring on the weaning of participants off the tobacco habit will be analysed.