Lung cancer is the leading cause of cancer-related death worldwide. In 2011, the largest lung cancer screening trial worldwide, the US National Lung Screening Trial, published a 20% decrease in lung cancer-specific mortality in the computed tomography (CT)-screened group, compared with the group screened by chest x-ray. On the basis of this trial, different US guidelines recently have recommended CT lung cancer screening. However, several questions regarding the implementation of lung cancer screening need to be answered. In Europe, several lung cancer screening trials are ongoing. It is planned to pool the results of the lung cancer screening trials in European randomized lung cancer CT screening (EUCT). By pooling of the data, EUCT hopes to be able to provide additional information for the discussion of some important issues regarding the implementation of lung cancer screening by low-dose CT, including: the determination of the optimal screen population, the comparison between a volume-based and diameter-based nodule management protocol, and the determination of optimal screen intervals.