Blood test reveals more than 20 types of cancer

New technologies that enable doctors to detect key biomarkers at earlier stages promise the change the face of cancer treatment, and blood testing is one area where some exciting progress is being made. The latest advance comes from scientists at the Dana-Farber Cancer Institute, who have published a study describing a new type of blood test that can detect more than 20 types of cancer, and even trace them back to their source.

There are a number of cancer-detecting blood tests in development around the world, which are designed to detect different kinds of biomarkers as early indicators of the disease. Some search for elevated levels of certain proteins, some for damaged DNA in white blood cells and others for irregular platelet RNA profiles, with differing degrees of success.

The new test was developed by scientists at private company Grail Inc. and was investigated by scientists from Harvard University’s Dana-Farber Cancer Institute.

The technology centers on the detection of methyl groups, which are small units of chemicals that can attach themselves to DNA and influence which genes are switched on or off.

When these patterns of on-and-off gene expression differ from the norm, they can be indicative of cancer, as we have seen demonstrated through previous studies on cancer-detection blood tests. The newly published study, however, does offer some particularly impressive and wide-ranging results.

The researchers applied the sequencing technology that scans for these irregularities to almost 3,600 blood samples, drawn from both healthy subjects and patients suffering from more than 20 types of cancer. It indicated the presence of the cancers with 99.4 percent accuracy, meaning that just 0.6 percent were incorrect diagnoses of healthy subjects.

But the test has the potential to go further than that. According to the investigators, the technology was able to reveal high-mortality cancers with a 76 percent accuracy, and among those, reveal stage one cancers with 32 percent accuracy, stage two cancers with 76 percent accuracy and stage three cancers with 85 percent accuracy.

Stage four cancers were detected with 93 percent accuracy, while 89 percent of the time, the test was able to correctly identify the organ or tissue where the cancer originated. The cancer types the test was able to reveal include breast, gall bladder, head, neck, lymphoid, lung, pancreatic and leukemia.

“Our previous work indicated that methylation-based assays outperform traditional DNA-sequencing approaches to detecting multiple forms of cancer in blood samples,” says the study’s lead author, Geoffrey Oxnard, MD, of Dana-Farber. “The results of the new study demonstrate that such assays are a feasible way of screening people for cancer.”