 The preliminary results of the pilot study on early lung cancer detection by spiral CT and PET launched in Milan in 2000 and published in the Lancet in 2003 showed a positive outcome, confirming the essential safety of spiral CT and a high proportion 95 of complete resections and stage I disease 77. However, the results at six years revealed a different picture, with an increasing number of advanced lung cancers being detected from the third to the fifth year, and no evidence of significant mortality reduction for lung cancer by annual CT monitoring of our cohort of heavy smokers. These data were confirmed by a meta-analysis conducted by two senior epidemiologists of Memorial Sloan-Kettering Cancer Center, Peter Bach and Colin Begg, of the three concurrent single arms studies: IEOINT, Mayo Clinic and Lee Moffitt Cancer Center trials. Such a meta-analysis demonstrated that annual CT increases by 3-4 fold the number of detected lung cancers but does not reduce the incidence of advanced and potentially lethal disease. These data strengthen the validity of the plan to continue clinical research on early lung cancer detection by a randomized controlled study in 2005. In fact there is an overwhelming consensus in the International scientific community that uncontrolled observational studies will not be able to provide further knowledge in this field. Only large randomised controlled clinical trial will hopefully provide convincing evidence on the magnitude of the benefit achievable by early detection programmes with spiral CT in heavy smokers. 