LUNG cancer could be detected around three months earlier using a biomarker blood test and CT scanning in high-risk patients.

A study involving more than 12,208 current and former smokers from Tayside, Glasgow and Lanarkshire found that diagnosis occurred on average 87 days sooner compared to standard NHS care, with the disease more likely to be at stages one or two when treatment can be more effective.

Professor Frank Sullivan, an expert in primary care medicine at St Andrews University and the chief investigator on the trial, said: “I hope that the results of this trial will have globally significant implications for the early detection of lung cancer by showing how a simple blood test, followed by CT scans, is able to increase the number of patients diagnosed at an earlier stage of the disease, when surgery is still possible and prospects for survival much higher.”

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The Early Detection of Lung Cancer Scotland (ECLS) trial uses a biomarker test to check the blood for a protein - known as an autoantibody (AAB) - which can be released by tumours up to three or four years before symptoms emerge.

Participants were current or former smokers aged 50 to 75, some with a family history of lung cancer, and were followed over two years.

The half allocated to the intervention group were tested for the lung cancer biomarker.

Those who tested positive received a chest X-ray and CT scan followed by follow up CT scans every six months until the end of the trial.

The control group followed the normal NHS pathway of being referred for tests if their GP suspected symptoms.

Between eight and nine in every ten people diagnosed with lung cancer die within five years of diagnosis, and there is currently no routine screening programme.

A previous Dutch-Belgian study of 13,131 men found a 24% reduction in mortality over 10 years using low-dose CT scanning as a screening tool, but the risks of false positives and limited scanning resources mean this is unlikely to be cost-effective at a population level.

The researchers leading the ECLS study, published in the European Respiratory Journal, state that using a biomarker test first "could potentially play a role in identifying those most at risk and who have most to gain from a targeted approach".

Over the two years of the trial, a total of 127 participants were diagnosed with lung cancer, with a statistically significant reduction in late-diagnosis risk among those in the intervention group.

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Incidence was highest, at 3%, among those in the intervention group who had tested positive for the biomarker.

In this group, 18 cases of lung cancer were detected over two years - 10 at stage one and two at stage two - meaning two thirds were picked up early.

Of the participants in the intervention group whose blood tests were negative, 0.7% went on to develop the disease and only 29% of cases were detected at the earliest stages.

For the control group receiving standard clinical care and diagnostics, 0.8% of participants had developed lung cancer by the end of the two year period and 30% were diagnosed at stages one or two.

Participants in the intervention arm were diagnosed with lung cancer on average 87.3 days earlier than the control group.

By the end of the two year trial, there had been 24 lung cancer deaths among the control group and 17 in the intervention group.

It is not yet clear whether the difference in mortality rates is statistically significant, but follow ups will take place again at five and 10 year intervals.

The cost for each case detected at early stage using the blood test and CT scanning intervention has been estimated at £116,000 per patient, but the researchers stress that this "does not include long-term costs of treatment and survival beyond the trial".

They also note that the blood test only succeeded in detecting biomarkers in 32% of those participants tested who did go on to develop lung cancer within two years.

They said this may be due to the tumours themselves suppressing the "immune responses (thereby leading) to less autoantibody production and detection".

They said further investigation would be needed into how often the test should be repeated.