 The MILD project is a randomized lung cancer screening trial whose primary aim is to evaluate the impact on mortality of early lung cancer detection through LDCT low-dose computed tomography in 2 groups: a control group undergoing a program of primary prevention with pulmonary function test evaluation and a group undergoing a periodic spiral CT associated with primary prevention and pulmonary function test evaluation. This last one is also randomized in two arms: yearly low-dose CT vs CT every 2 years. 