A blood test that detects very small amounts of tumour DNA in lung cancer patients may predict how well patients will respond to treatment and the likelihood of the cancer returning.
Tumour cells release small fragments of circulating tumour DNA (ctDNA) into the bloodstream which can give important clues about the disease. However, measuring ctDNA accurately is challenging, and patients may be incorrectly assessed as ctDNA negative. In a study published in Nature Medicine, researchers at the Francis Crick Institute in London, and University College London worked with precision oncology company Personalis to test its NeXT Personal platform. This platform detects extremely low levels of ctDNA – just one part per million.
Professor Charles Swanton, the study's lead investigator, emphasised the test's potential impact: 'Lung cancer is one of the most common types of cancer in the UK, but it's hard to treat, with a high relapse rate. It's vital to understand who would benefit from more aggressive treatment, especially for patients with stage one disease who are often diagnosed during CT screening for those at a higher risk. Using sensitive ctDNA tests is one way to do this, which we hope will maximise clinical benefit and minimise unnecessary treatment for individual patients.'
The study involved 171 patients with early stage lung cancer who had had their blood tested before undergoing surgery to remove their tumours. The patients with detectable ctDNA in their blood plasma were found to have worse outcomes compared to those without ctDNA.
The higher sensitivity of this test allowed researchers to categorise patients into three groups based on the amount of ctDNA detected in their blood: ctDNA-high, ctDNA-low, and ctDNA-negative.
Those who tested negative for ctDNA had a five year survival rate of 100 percent and their tumour did not return during this time. Patients with detectable ctDNA had lower survival rates which varied based on the ctDNA levels: 61.4 percent for ctDNA-low and 48.8 percent for ctDNA-high.
'We've shown that the presence or absence of tumour DNA in the blood was strongly predictive of prognosis,' said Dr James Black, co-lead author and postdoctoral clinical fellow at the Francis Crick Institute. 'ctDNA testing, especially using ultrasensitive platforms, could help clinicians make more informed decisions about treatment and give patients a more accurate idea of how their disease might progress. More research to validate these tests will help to get them on the agenda for regular clinical use.'
Sources and References
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Tumour DNA in the blood can predict lung cancer outcome
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Ultrasensitive ctDNA detection for preoperative disease stratification in early-stage lung adenocarcinoma
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Ultrasensitive ctDNA detection improves risk prediction in early-stage lung cancer
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Even low levels of ctDNA may be linked to recurrence risk in early lung cancer, study finds
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