A simple blood test that can detect more than 50 types of cancer before any clinical signs or symptoms of the disease emerge in a person is accurate enough to be rolled out as a screening test, according to scientists. The Guardian reports: The test, which is also being piloted by NHS England in the autumn, is aimed at people at higher risk of the disease including patients aged 50 or older. It is able to identify many types of the disease that are difficult to diagnose in the early stages such as head and neck, ovarian, pancreatic, esophageal and some blood cancers. Scientists said their findings, published in the journal Annals of Oncology, show that the test accurately detects cancer often before any signs or symptoms appear, while having a very low false positive rate.
The test, developed by US-based company Grail, looks for chemical changes in fragments of genetic code “cell-free DNA (cfDNA)” that leak from tumors into the bloodstream. The Guardian first reported on the test last year and how it had been developed using a machine learning algorithm a type of artificial intelligence. It works by examining the DNA that is shed by tumors and found circulating in the blood. More specifically, it focuses on chemical changes to this DNA, known as methylation patterns. Now the latest study has revealed the test has an impressively high level of accuracy. Scientists analyzed the performance of the test in 2,823 people with the disease and 1,254 people without. It correctly identified when cancer was present in 51.5% of cases, across all stages of the disease, and wrongly detected cancer in only 0.5% of cases.
In solid tumors that do not have any screening options “such as esophageal, liver and pancreatic cancers” the ability to generate a positive test result was twice as high (65.6%) as that for solid tumors that do have screening options such as breast, bowel, cervical and prostate cancers. Meanwhile, the overall ability to generate a positive test result in cancers of the blood, such as lymphoma and myeloma, was 55.1%. The test correctly also identified the tissue in which the cancer was located in the body in 88.7% of cases.
Read more of this story at Slashdot.