Scientists have developed a single blood test to detect eight common cancer types and their location of origin within the body.
CancerSEEK is a non-invasive screening test or liquid biopsy aimed at tracking tumour formation and progression from fragments of tumour DNA in the bloodstream. Unlike previous liquid biopsy tests which tend to assess only the presence of circulating tumour DNA (ctDNA), CancerSEEK simultaneously detects cancerous proteins. By using a combination of eight aberrant proteins and 16 ctDNA mutations, the new test is able to identify ovarian, liver, stomach, pancreatic, esophageal, colorectal, lung and breast cancers, which account for 60 percent of the estimated cancer deaths in the US.
'The use of a combination of selected biomarkers for early detection has the potential to change the way we screen for cancer, and it is based on the same rationale for using combinations of drugs to treat cancers,' said Dr Nickolas Papadopoulos, at Johns Hopkins University School of Medicine in Baltimore, Maryland, who led the study. The research was published in Science.
The test was given to around 1000 patients with non-metastatic cancers. CancerSEEK correctly diagnosed 70 percent of the cases and successfully excluded false positive results with a specificity above 99 percent. However, the performance of the test varied significantly with the type of tumour: it detected 98 percent of ovarian cancers, but only 33 percent of breast cancers. In addition, the test outcomes substantially improved when more advanced cancerous lesions - stage III diseases, were examined.
'This paper is provocative,' Professor Alberto Bardelli, at the Candiolo Cancer Institute in Turin, Italy told Nature News. 'It points to the fact that we should stop looking at a little part of the picture. Instead, we need to see all of the sources of information in the blood.'
CancerSEEK could be potentially administered by primary care providers at the time of other routine blood work, and the researchers estimate that the cost of the test could be less than US$500, comparable with a colonoscopy.
Experts noted some drawbacks of the study. 'This looks promising but with several caveats and a significant amount of further research is needed before we can even contemplate how this might play out in screening settings,' said Dr Mangesh Thorat, deputy director of the Barts Clinical Trials Unit, Queen Mary University of London. 'This is only a case-control study, and therefore needs further evaluation in large cohorts more representative of general population where such screening might be introduced.'
Researchers led by Dr Papadopoulos have begun to address those concerns and have started a new study that will test CancerSEEK in at least 10,000 healthy individuals.