New blood test can detect 50 types of cancer

Yolanda Curtis
April 3, 2020

The company is using the power of next-generation sequencing, population-scale clinical studies, and state-of-the-art computer science and data science to enhance the scientific understanding of cancer biology, and to develop its multi-cancer early detection blood test. GRAIL is located in Menlo Park, California and Washington, D.C. It is supported by leading global investors and pharmaceutical, technology, and healthcare companies. In 96% of the tests, the samples correctly identified the tissue that the cancer had come from.

The test is based on DNA that is shed by tumours and found circulating in the blood and the chemical changes to this DNA, known as methylation patterns. However, as the cfDNA can come from other types of cells as well, it can be hard to pinpoint cfDNA that comes from tumours. The team then taught the system which groups reflected which type of cancer.

A blood test could detect different forms of cancer. The classifier was trained using a methylation database of cancer and non-cancer signals in cfDNA. Detecting cancers at their earliest stages, when they are less aggressive and far more treatable, is a key objective for the test.

The results also highlighted some other drawbacks to the test.

Seiden's team analyzed blood samples from more than 4,300 participants with and without cancer.

The researchers found that the classifier's performance was consistent in both the training and validation sets, with a false positive rate of 0.7% in the validation set. Across all 50 cancers, the true positive rate slipped to around 44 percent. The samples from patients with cancer represented more than 50 cancer types, including breast, colorectal, esophageal, gallbladder, bladder, gastric, ovarian, head and neck, lung, lymphoid leukemia, multiple myeloma, and pancreatic cancer.

Having an accurate blood test to screen for cancers, especially those for which no screening test now exists, has been a goal for years, said Dr. Len Lichtenfeld, deputy chief medical officer of the American Cancer Society. A related study was published in Cancer Epidemiology, Biomarkers & Prevention.

Detection improved with each cancer stage. As we have written before, whilst detecting cancer at earlier stages I or II (when treatment is more likely to be successful) is an admirable aim, it is not without its challenges. For the 50 cancers together, the corresponding rates were 18%, 43%, 81%, and 93%, respectively.

However, more research is needed to improve the ability of the cancer screening test and we still need to figure out how it might work in a real cancer screening scenario.

Today, most of the deadly cancers have no guideline-suggested screening tests available, and as a outcome, most of the cancers are identified in late stages, when survival chances are very low.

"The test seems particularly sensitive at detecting common cancers, such as lung and colon cancer, as well as highly lethal cancers that now have no known screening tests, such as pancreatic and esophagus cancer", Seiden said. Among other things, that is why scientists have been looking for some time for a possibility of cancer through blood to identify tests. The results were published in the Annals of Oncology.

Such a blood test is the "holy grail" for cancer research, although more work is needed to find one which works perfectly.

Cancer is one of the most common causes of death, but the huge variation in types of cancer can make early detection a challenge.

The team said that the results are exciting as they are offering the possibility of a new way to screen for cancers that are extremely hard to detect. "(2020) Sensitive and specific multi-cancer detection and localization using methylation signatures in cell-free DNA", Annals of Oncology.

Other reports by iNewsToday