A single blood test may be the future of early detection of a variety of cancers.
Results of a preliminary trial show that tumours could be tracked from a simple blood draw. A study in this regard was published on Thursday in the journal Science. It suggests that the test detected disease in about 70% of more than 1,000 people who had already been diagnosed with cancer.
Researchers of the study hope that this would eventually lead to a test that is simpler and cheaper than the intensive sequencing involved in some other liquid biopsies.
“They end up with performance that is similar to other approaches, but with what looks to be a much more cost-effective approach,” said Nitzan Rosenfeld, a cancer researcher at the University of Cambridge.
Use of liquid biopsies to track cancer progression is not new and is used to guide physicians as they formulate a treatment plan.
However, oncologist Nickolas Papadopoulos at the Johns Hopkins Kimmel Cancer Center in Baltimore, Maryland, and his colleagues wanted to develop a test that could detect cancers early, when they are easier to treat.
Such tests are challenging: small tumours don’t release as much DNA into the bloodstream as larger tumours. False positives are also a concern for tests intended to be administered to large populations of healthy individuals — an incorrect result can cause people undue stress and lead to unnecessary and potentially harmful treatments.
Researchers looked for ways to make their liquid biopsy more sensitive without also raising the risk of a false-positive result. The test they developed — dubbed CancerSEEK — examines the levels of eight proteins and presence of mutations in 16 genes.
The liquid biopsy was tested on people who already had been diagnosed with one of eight cancers: ovarian, liver, stomach, pancreatic, esophageal, colorectal, lung or breast. Individuals whose cancer had spread to other parts of the body were excluded, so that the researchers could focus on early stages of the disease.
The effectiveness of CancerSEEK varied widely depending on the cancer: it detected 98% of ovarian cancers, but only 33% of breast cancer cases. It was able to pinpoint the organ in which the disease had taken root in about 63% of patients. The test performed better on later-stage cancers than on earlier ones, finding 78% of stage III disease versus 43% of stage I tumours.
Rosenfeld, who is also chief scientific officer at the liquid-biopsy company Inivata in Cambridge says, “Even if you only catch half of the cancers, that’s great. We are looking to see whether CancerSEEK is can also detect undiagnosed cancers.”