By Dr Matthew Callister, Consultant Respiratory Physician
CT screening in Europe took a leap forward this week with the publication of the mortality results from the NELSON screening study. NELSON was a population-based controlled trial that ran in the Netherlands and Belgium commencing in 2004. 15,792 individuals were enrolled and those randomised to screening underwent low-dose CT at baseline, 1, 3, and 5½ years after randomisation. The trial was the first to use volumetry and a nodule management strategy based on analysis of volume doubling time, and analysis of lung cancer risk according to nodule size and growth rate was key to developing the British Thoracic Society Pulmonary Nodule guidelines.
The mortality results, presented in the Presidential Symposium at the International Association for the Study of Lung Cancer (IASLC) World Conference on Lung Cancer (WCLC) 2018 in Toronto, showed a significant reduction in lung cancer mortality in the screened versus control arm. The cumulative number of male lung cancer deaths in the screened arm 10 years after randomisation was 157 compared to 214 in the control arm. Over 80% of the NELSON cohort were male, and the Lung Cancer Mortality Rate Ratio in men was 0.74 (95% CI 0.60-0.91). The mortality reduction in women was numerically greater (Rate Ratio 0.61) although lacked significance at the 10 year mark (95% CI 0.35-1.0). Although the combined male and female rate ratio was not presented, it seems very likely that a significant reduction will be seen across the whole population. What’s more, the size of the mortality reduction exceeds that seen with the National Lung Screening Trial, possibly due to the fact that the control arm in NELSON had no screening, whereas in NLST the control arm had annual chest X-ray screening.
So where does this leave lung cancer screening in the UK? The UK National Screening Committee has previously indicated that it would reconsider this after publication of NELSON results. The paper is now awaited in print form and will no doubt be scrutinised closely. However, the initial results shown in Toronto will now add huge impetus to calls to introduce a national screening programme.
What that screening programme will look like will be the subject of much debate. Issues that still need resolving include which high-risk people to invite, how to modify nodule management protocols to reduce harms such as interventions for benign disease and over-diagnosis, and how to best integrate smoking cessation into screening programmes. However, the biggest challenge is participation. A recent analysis showed that only 1.9% of eligible US people accessing screening in 2016, despite it having been approved by the US screening committee (USPSTF) three years earlier. Screening pilots in London, Manchester and Liverpool using a ‘Lung Health Check’ approach have shown much higher levels of participation, and generated much interest in Toronto.
Meanwhile, the full paper and response of the NSC are keenly awaited.