Lung cancers present late, allowing most sufferers little chance of curative treatment. Presenting symptoms are usually non-specific and give the primary-care physicians little to look out for to separate the presentation of lung cancer, which is the most serious of diseases, from the common cold, a respiratory tract infection, fibromyalgia or any other self-limiting condition of little long-term consequence that he or she sees in daily abundance.¹ It has been known for years however, that the most favourable presentation for lung cancer is the chance discovery on a routine chest radiograph, and this was one of the drivers for the chest radiograph to be used as a screening tool for lung cancer in the 1950s and 1960s. However, although chest radigraph screening studies, where usually individuals are randomised to an x ray annual screen or simple follow-up, did disclose more cancers in the active study arm, their mortality was not improved.^2–4 These studies have been criticised for several reasons, including inadequate number of entrants, non-compliance in the follow-up only arm and claims that, maybe after all, there was a potential advantage in mortality for the screen-discovered cancers. Nevertheless, the issue was dropped until the development of low-dose multi-slice computed tomography scanning made computed tomography suitable for studying large numbers of people with only a small radiation exposure. Over the past 10 years, there have been several hypothesis-generating studies on populations with differing degrees of risk for developing lung cancer who have undergone prevalence and incidence computed tomography screening in non-randomised studies. These studies have been carried out mainly in Japan and the United States, and have incorporated healthy volunteers of middle or late age (45 years or more), of sufficient health status to be likely to live for …