Could a blood test detect cancer early?
5th June 2017 – A simple blood test that could reliably detect cancer in its early stages could one day be a possibility, say scientists.
Currently, the only way to make a firm cancer diagnosis is from a biopsy in which a small amount of bodily tissue is removed for analysis.
However, a blood test for cancer could lead to cancer being diagnosed before it becomes entrenched in the body.
Scientists say it would revolutionise cancer medicine. But would it be reliable and how close is the prospect for this kind of test?
Why a blood test for cancer?
Most cancers are diagnosed by surgically removing a portion of tissue to find out if a tumour is cancerous.
The procedure may be uncomfortable or painful.
Also, it will probably be carried out after symptoms have already become apparent and when the cancer might be at an advanced stage.
A blood test carries the prospect of being cheap, relatively painless and capable of screening for cancer long before it has become established in the body. That would lead to better cancer survival rates, as early detection is key to effective treatment.
It could even become part of a routine health check performed by a GP.
So, why isn't it being done now?
A so-called 'liquid biopsy' would depend on detecting genetic mutations in the blood that indicate the presence of cancer.
The equipment used would have to be highly sensitive to spot these small amounts of tumour DNA.
Also, tests have only been carried out so far on people with advanced cancer. There is no way of knowing at the moment whether it is sufficiently effective at finding cancer in its early stages.
What progress has been made?
A study presented at the annual meeting of the American Society of Clinical Oncology shows promising results using equipment to measure genetic mutations indicating the presence of cancer with a high degree of accuracy.
In 90% of cases involving 124 patients with advanced breast cancer, lung cancer, and prostate cancer, at least 1 of the mutations identified in a patient's tumour tissue was also found in the blood.
Scientists from the Memorial Sloan Kettering Cancer Centre in New York, which led the study, say the test was the most advanced to date and call the results "very promising".
The findings should be treated with caution as they have been presented at a conference and have yet to be published in a peer-reviewed journal.