Low-dose CT for lung cancer screening: benefit outweighs potential harm

December 03, 2020

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.

Overdiagnosis detects lung tumours that would never have been noticed without screening and would never have required treatment. The risk of being overdiagnosed also varies greatly in the studies analysed: Out of every 1000 people invited to screening, 0 to 22 might be affected by an overdiagnosis. The risk of overdiagnosis for people diagnosed with lung cancer during the screening phase ranged between 0 and 63 percent in the studies. This highlights the importance of an optimized screening strategy to keep the risk of overdiagnosis low.

For the high-risk group of heavy (ex-)smokers, however, the benefit outweighs these aspects of harm. In summary, there is a hint of a benefit of low-dose CT screening versus no screening.

Screening strategy is important

An optimal screening strategy is the basis for a positive benefit-harm ratio of low-dose CT for lung cancer screening. For this purpose, the high-risk population to be examined must be defined as precisely as possible by means of smoking behaviour and remaining life expectancy. As in the studies analysed, lung cancer screening should be supported in practice by specific quality assurance measures (diagnostic algorithm, types of devices, follow-up, etc.).

Further optimization of low-dose CT for lung cancer screening is currently ongoing. For example, up to the end of 2024, a European study is investigating the safety of risk-based examination intervals and strategies for implementation: The EU project "4-IN THE LUNG RUN", in which German research institutions are also involved, is to include a total of 24,000 people in an RCT.
-end-
Procedure of report production

IQWiG published the preliminary results in the form of the preliminary report in July 2020 and invited comments. After completion of the commenting procedure, the project team revised the preliminary report and sent it as a final report to the contracting agency, the G-BA, in October. The two written comments received were published in a separate document at the same time as the final report.

An English-language extract of the report will be available soon. If you would like to be informed when this document is available, please send an e-mail to info@iqwig.de.

Institute for Quality and Efficiency in Health Care

Related Lung Cancer Articles from Brightsurf:

State-level lung cancer screening rates not aligned with lung cancer burden in the US
A new study reports that state-level lung cancer screening rates were not aligned with lung cancer burden.

The lung microbiome may affect lung cancer pathogenesis and prognosis
Enrichment of the lungs with oral commensal microbes was associated with advanced stage disease, worse prognosis, and tumor progression in patients with lung cancer, according to results from a study published in Cancer Discovery, a journal of the American Association for Cancer Research.

New analysis finds lung cancer screening reduces rates of lung cancer-specific death
Low-dose CT screening methods may prevent one death per 250 at-risk adults screened, according to a meta-analysis of eight randomized controlled clinical trials of lung cancer screening.

'Social smokers' face disproportionate risk of death from lung disease and lung cancer
'Social smokers' are more than twice as likely to die of lung disease and more than eight times as likely to die of lung cancer than non-smokers, according to research presented at the European Respiratory Society International Congress.

Lung cancer therapy may improve outcomes of metastatic brain cancer
A medication commonly used to treat non-small cell lung cancer that has spread, or metastasized, may have benefits for patients with metastatic brain cancers, suggests a new review and analysis led by researchers at St.

Cancer mortality continues steady decline, driven by progress against lung cancer
The cancer death rate declined by 29% from 1991 to 2017, including a 2.2% drop from 2016 to 2017, the largest single-year drop in cancer mortality ever reported.

Cancer-sniffing dogs 97% accurate in identifying lung cancer, according to study in JAOA
The next step will be to further fractionate the samples based on chemical and physical properties, presenting them back to the dogs until the specific biomarkers for each cancer are identified.

Lung transplant patients face elevated lung cancer risk
In an American Journal of Transplantation study, lung cancer risk was increased after lung transplantation, especially in the native (non-transplanted) lung of single lung transplant recipients.

Proposed cancer treatment may boost lung cancer stem cells, study warns
Epigenetic therapies -- targeting enzymes that alter what genes are turned on or off in a cell -- are of growing interest in the cancer field as a way of making a cancer less aggressive or less malignant.

Are you at risk for lung cancer?
This question isn't only for people who've smoked a lot.

Read More: Lung Cancer News and Lung Cancer Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.