A contemporary infographic on the benefits and harms of lung cancer screening has been developed by an international group of experts. 

In a Spotlight article published in Lancet Respiratory Medicine the team from the UK and the US  said that the infographics that currently existed to help clinicians in conversations with their patients around screening could be misleading as they represented outcomes based on the almost 20 year old US National Lung Screening Trial (NLST) protocol.

“Our new infographic represents a contemporary interpretation of the findings of NLST using a modern protocol,” they wrote.

In order to reflect contemporary practice the team analysed individual-level data from the NLST to represent outcomes that would have been observed if Lung-RADs, the current protocol in the US, had been used to manage low dose CT findings.

The Lung-RADs differs from the NLST because it categorises small pulmonary nodules as negative screens, “which can substantially reduce the number of false-positives and the subsequent need for additional scans  and invasive procedures,” they wrote. 

To estimate overdiagnosis they applied the percentage of screen-detected lung cancers that  were overdiagnosed in NLST to the Lung-RADs screen detected cases.  Lives saved were estimated by taking the difference between lung cancer deaths per 1000 between the NLST low-dose CT and chest x-ray arms and reduced it by the relative reduction in sensitivity from Lung-RADs.  

They discovered that if Lung-RADS had been used in the NLST 779 people per 1,000 would have had all normal screen results by Lung-RADs and no lung cancer diagnosis.

Another 180 people would have had one or more abnormal results (false-positives) requiring a follow-up low dose CT at 3 or 6 months, but no lung cancer diagnosis. Of these, 13 would require an invasive procedure to rule out  lung cancer.

Furthermore, 1 in 2500 screened would have a major complication from an invasive procedure, and 1 in 5000 people screened would die.

And 41 per 1000 people would be diagnosed with lung cancer, among whom approximately four cases represented overdiagnosis and three cases presented lung cancer deaths prevented because of screening.

Infographic depicting estimated outcomes in the US National Lung Screening Trial under the Lung-RADS nodule management protocol

The authors cautioned that their data would underestimate the lung cancer mortality benefit from continual low-dose CT screening because the NLST had only three annual screens and the control arm used  chest x-ray screening.

Benefits and harms of screening also varied on the basis of underlying lung cancer risk.

“With these caveats, we hope that our infographic will facilitate improved communication about lung screening to providers, patients, and the public,” they concluded.