Several studies have examined the effectiveness of low-dose spiral chest CT scan screening for early detection of lung cancer. Currently, most patients with lung cancer are diagnosed at an advanced stage. Early detection of lung cancer could help reduce the high mortality rate associated with lung cancer. It is hoped that the advanced technology of this new screening procedure may prove to be comparable to the reduction in mortality associated with having the recommended mammographies for early detection of breast cancer.

However, unlike most cancers, lung cancer is associated with a specific behaviour—namely, smoking cigarettes. It has been proposed that informing cigarette smokers of negative lung cancer screening results could give them permission, licence or a “green light” to continue smoking. If a screening procedure leads to increased smoking rates, it is possible that any health benefits associated with early detection of lung cancer would be offset by an increase in the prevalence of lung cancer due to increased smoking rates.

Fortunately, several non-randomised screening programmes have examined this concern and, so far, negative screening results do not appear to increase smoking rates. For example, we found that CT screening results did not affect the smoking rates of 1475 adults with a smoking history of at least 20 pack-years at 1-year follow-up.1 Interestingly, in this same sample we found that three abnormal screens over a 3-year period promoted smoking abstinence (41.9%). Those with three negative screens still had a higher than expected quit rate (19.8%) over the 3 years.2

The study by Ashraf and colleagues in this issue of Thorax (see page 388) is unique in that participants were randomised to receive either CT screening or to not have any screening.3 A randomised study design helps to further understand the possible effects that lung cancer screening may have on smoking rates. The fact that the authors also found that the screening and control subjects both demonstrated a quit rate of almost 12% is further support of previous research findings from single-arm studies that negative screening results do not promote or encourage continued cigarette smoking. The study also demonstrates the strength of a randomised controlled trial, and showed that smoking cessation was equal in the two arms regardless of whether or not the subjects received CT screening. Without the control arm it would be possible mistakenly to attribute the successful smoking cessation to having CT screening.

What is striking is that the quit rate found in participants in CT screening—either in randomised trials or single-arm studies—is higher than expected. Participants usually have a 20 pack-year history of smoking so they are long-term addicted smokers. That almost 12% quit at 1 year in this study and that 14% quit at 1 year in our study shows that this is a population of smokers with a high motivation to quit smoking. Our attempt to take advantage of this teachable moment by enhancing smoking abstinence with either internet resources or written materials proved ineffective.4 It is our current opinion that more intensive, truly multidisciplinary approaches are needed for smoking cessation. We therefore suggest that smoking cessation interventions that combine pharmacotherapy with nicotine counselling and use screening results to enhance motivation for quitting smoking may prove to be efficacious for this population at high risk for lung cancer. Hopefully, future studies can design and implement efficacious tailored smoking cessation programmes for participants in lung cancer screening programmes.5