Single blood test for cancer 'shows promise'
19th January 2018 – Doctors and scientists in the US say they have developed a blood test that can identify 8 common types of cancer.
The test, called CancerSEEK, has been used to screen for ovary, liver, oesophagus, pancreas, stomach, colorectal, lung, and breast cancer.
Diagnosing cancer in its early stages
A universal test could detect cancers early enough to allow a cure by surgery alone. In some cases, early detection could make other treatments more successful.
Researchers from Johns Hopkins University in Baltimore say the breakthrough could change the future of cancer screening.
Development of the 'liquid biopsy' test is still in its early stages. "To actually establish the clinical utility of CancerSEEK and to demonstrate that it can save lives, prospective studies of all incident cancer types in a large population will be required," the researchers conclude.
Nevertheless, they believe that this study "lays the conceptual and practical foundation for a single, multi-analyte blood test for cancers of many types".
"This paper is a step along the way to a possible blood test to screen for cancer, comments Nicholas Turner, professor of molecular oncology at The Institute of Cancer Research in London, "and the data presented is convincing from a technical perspective on the blood test."
However, he cautions that "the study does not support use of the blood test outside research studies, as it has not shown yet whether the blood test has the characteristics required for population screening, nor whether the blood test will improve outcome."
Looking at mutations and proteins
The new test measures circulating tumour DNA (ctDNA) from 16 genes as well as 8 protein biomarkers, and then uses machine-based learning to analyse the data.
Image credit: Science
The test was evaluated in 1,005 patients who had stage 1 to stage 3 cancers that had not spread to other parts of their body.
It was able to detect the presence of cancer in 70% of patients on average. This ranged from a high of 98% for ovarian cancer to a low of 33% for breast cancer.
For 5 types of cancers that have no screening tests – ovarian, liver, stomach, pancreatic and oesophageal cancers – sensitivity ranged from 69% to 98%.
The average age of the patients at diagnosis was 64. The most common stage at presentation was stage 2 (49%); 20% of patients had stage 1 disease; and 31% had stage 3 disease.
The tests produced 'false positives', in which the test returned a diagnosis of cancer without cancer apparently being present, in 1% of 812 healthy people with no history of cancer.