For heavy (ex-)smokers, lung cancer screening using low-dose computed tomography (low-dose CT, LDCT) offers more benefit than harm: The procedure can save a number of people from dying of lung cancer; for some of them, it might also prolong overall survival. This is the conclusion drawn by IQWiG in its final report commissioned by the Federal Joint Committee (G-BA).

Overall, the IQWiG project team sees a hint of a benefit of low-dose CT for lung cancer screening versus no screening for the outcome "mortality". This benefit is accompanied by harm from false-positive screening results and overdiagnosis. For the high-risk group of heavy (ex-)smokers, however, the benefit outweighs the potential harm.

Low-dose CT for lung cancer screening under evaluation
Lung cancer is one of the leading causes of cancer deaths worldwide. Men are diagnosed at a median age of 70, women at 69. Lung cancer is usually discovered at a late stage, so that five years after diagnosis, only one fifth to one sixth of people affected are still alive.

At present, there is no systematic screening for lung cancer in Germany and LDCT is not part of the scope of services provided by statutory health insurance. Pursuant to the Radiation Protection Act, the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU) is currently evaluating whether radiation exposure due to several years of LDCT screening (including follow-up diagnostics) is permissible.

Low-dose CT screening reduces lung cancer mortality

The results of eight randomized controlled trials (RCTs) with more than 90,000 people provide an indication of a benefit of LDCT screening for heavy (ex-)smokers: Within about ten years, it can prevent about 5 out of every 1,000 people from dying of lung cancer.

In contrast, no statistical advantage of LDCT screening is shown for all-cause mortality. This could be because people saved from death by lung cancer die from other tobacco-related diseases instead, such as other types of cancer or cardiovascular diseases. However, the results of meta-analyses of all pooled study data suggest a reduction in all-cause mortality.

In the overall weighing of disease-specific mortality and all-cause mortality, in its final report IQWiG therefore concludes that there is a hint of a benefit of low-dose CT for lung cancer screening versus no screening.

Misdiagnosis and overdiagnosis are rather rare

A false-positive result alone means harm to the people affected. The diagnosis of lung cancer also requires histological or cytological confirmation, which - like any diagnostic procedure and treatment - carries the risk of side effects and complications. For instance, surgical interventions are performed without a lung tumour always being present, sometimes with serious side effects. However, the risk of harm in the studies included varies: 1 to 15 out of every 1000 people underwent unnecessary surgery due to false-positive screening results.

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