Scientists in the UK have developed a blood test which detects the recurrence of lung cancer in patients up to a year before the disease can be detected by CT scans and X-rays.
The groundbreaking TRACERx study, funded by Cancer Research UK, identified the cause of relapse of the disease and how it spreads, in a discovery that could lead to earlier treatment for patients.
By analysing tumours from 100 lung cancer patients, researchers at medical research centre Francis Crick Institute found that those containing a higher proportion of "unstable chromosomes" - those which cause genetic chaos and allow the tumour to evolve - were four times more likely to encounter a relapse or die within two years.
Genetically diverse tumours are harder to treat as they are more likely to spread and become drug-resistant.
In a study using 96 of those 100 patients, scientists screened their blood for circulating tumour DNA - bits of DNA that had "broken off" from a tumour - in order to uncover defects present in the patient's cancer.
They used this information to analyse blood samples from 24 patients who had undergone surgery, and were able to identify more than 90% of cancer cases likely to return, up to a year before other clinical methods, such as CT scans or an X-ray, could detect the illness.
Lung cancer is the leading cause of cancer death among men and women in the UK, causing more than 20 per cent of cancer deaths, according to Cancer Research UK.
Scientists also compared levels of tumour DNA in patients' blood before and after post-surgery chemotherapy in the study, which was published in science journal Nature.
They found that the cancer returned when levels of tumour DNA in the blood were not reduced after the treatment, showing that the tumour had become partially resistant to the chemotherapy.
The findings could pave the way for the development of new drugs to target resistant parts of lung cancer tumours.
"In the future, patients could be offered personalised treatments that target parts of the cancer responsible for relapse following surgery," Dr Christopher Abbosh, lead author of the study, said.
"Using circulating tumour DNA, we can identify patients to treat even if they have no clinical signs of disease, and also monitor how well therapies are working.
"This represents new hope for combating lung cancer relapse following surgery, which occurs in up to half of all patients."
TRACERx is the first of its kind to trace the evolution of the cancer in real time, from diagnosis to its death.
- PA, AAP