Randomised controlled studies such as the national lung screening trial and the national trial have indicated that low-dose CT screening can reduce lung cancer mortality among individuals with a heavy smoking history. However, the epidemiology of lung cancer in Asia is quite different from Western countries. Lung cancer is increasingly diagnosed in women and in individuals who have never smoked, raising concerns about whether traditional high-risk-based screening criteria are sufficient for Asian populations.

In addition, current lung screening trials have focussed on selective strategies tackling high-risk individuals rather than evaluating lung cancer screening in a non-risk-based population. So therefore we launched non-risk-based screening and targeting all the participants to perform a low-dose CT screening. We aimed to find the real high-risk population because we can see there are many cases of lung cancer in Asia not found by CT scans.

What was the study design?

This is a prospective interventional cohort study and a non-randomised clinical study. We set two groups in our study, one is a screening cohort and the other is the non-screening cohort. In the screening cohort the participants were from the LUNG-CARE Project who underwent a one-time low-dose CT screening after providing informed consent. The comparison cohort included participants from the same geographical region and age range who did not participate in the screening cohort. This is the study design.

What were the key findings?

We found a clear stage shift associated with low-dose CT screening and after a median follow-up of 7 years we found that low-dose CT screening was associated with a significant reduction in lung cancer mortality with a hazard ratio of 0.45. In a sex-stratified analysis we also found that mortality was reduced in both sexes with a greater benefit in women when compared with men.

What could be the clinical significance of these results?

Our study found that the LUNG-CARE project represents the first project in non-risk-based lung cancer screening programme and was associated with lower lung cancer specific mortality than that observed in a non-screened population from the same region. Second, compared with traditionally defined high-risk individuals, so-called non-high-risk patients showed better survival and greater curative potential through early detection.