Lung screening: Benefits vs risks

4 minute read

The overdiagnosis worry is ever present.

Australia is among the first in the world to make a large investment into lung cancer screening, but Cancer Australia’s national program is not without risks.

In May, the Australian Government tipped in $6.9 million to explore the feasibility of a national lung cancer screening program.

Cancer Australia is leading the early design of a potential national lung cancer screening program comprising two-yearly low dose computed tomography scans in high-risk individuals.

The hope is that screening will help address the problem Australia has right now where only 12% of lung cancer is diagnosed at Stage 1 and the five-year survival rate is approximately 18%.

Screening has been shown to reduce mortality by 20% to 33%.

Australia is acting boldly by establishing this program; the UK is holding off on developing similar screening program, despite having invested in research into the cost-benefits over many years.

“There is no national screening program for lung cancer in the UK. This is because: it isn’t clear that screening everyone saves lives from lung cancer, the tests have risks, they can be expensive,” Cancer Research UK states on its website.

NHS England is looking into using low dose CT scans for current or ex-smokers, however.

The concern around overdiagnosis stems from lung cancer screening trials such as NELSON and NSLT, which showed overdiagnosis rates in the 8% to 18% range, with other studies suggesting false positive rates could be as a high as 20%.

In the first ten years of the lung cancer screening program, Cancer Australia estimates around 70% of lung cancers will be diagnosed at an early stage, reducing mortality in the screened population by 20%, and preventing over 12,000 deaths.

Cancer Australia proposed a number of measures to minimise the risks of overdiagnosis in its report to the Department of Health recommending a national screening program late last year.

Cancer Australia suggested using low dose CT with volumetric analysis, which appeared to be the driver behind a 1.2% false positive rate in the NELSON trial.

They also proposed using a risk assessment tool to determine eligibility for screening among an already targeted population (smokers and former smokers in the 50 to 74 years-of-age range), and adopting “node nodule management protocols coupled with advances in image analytics”.

In its report, Cancer Australia also proposed a national screening register that would capture stage shift and mortality data.

Associate Professor Robert Stirling, a respiratory specialist at Alfred Health and Monash University, told Allergy and Respiratory Republic that this register should track the outcomes of patients with true and false screening results. It is unclear if the register will track this information at this stage.

“These measures will ensure that the impacts of investigation and the additional medical activities undertaken do not cause harm to patients or result in excessive cost burdens,” he said.

“A national quality register could confirm we are responding effectively to patients safely and without draining resources from non-screen detected patients.”

It has been suggested that state cancer registers could capture care outcomes, but Associate Professor Stirling pointed out that state registers lack clinical data, including cancer stage.

Mark Brooke, the CEO of Lung Foundation Australia, said the benefits of a national screening program outweighed the risks.

“Lung Foundation Australia acknowledges that no system is perfect but a lack of action on screening had led to late-stage diagnosis of lung cancer,” he said.

“Stigma and therapeutic nihilism have held back lung cancer care, research investment and community support for too long, often to the detriment of lung cancer patients and their families, and particularly for Aboriginal and Torres Strait Island people who are disproportionately impacted by lung cancer,” he said.

In July, the federal government granted the Lung Foundation Australia $1.4 million to bolster education and training. But more is needed, Mr Brooke said.

“We encourage government to make urgent investment to ensure the recommendations are fully implemented, evaluated and that a national targeted lung cancer screening program moves beyond pilot to full implementation within five years,” said Mr Brooke.

Lung cancer is Australia’s biggest cancer killer, and around 13,000 Australians diagnosed each year, making it the fifth most common cancer. It is also a cancer with a smoking stigma, with four in five patients classified as current or former smokers – a fact that has previously hindered research and investment.

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