Blood Test Detects Multiple Types Of Cancer

Researchers at the Dana-Farber Cancer Institute and other cancer research institutions have
begun developing a new blood test that is capable of screening for various types of cancer with high rates of accuracy. Investigators reported their results at the European Society for Medical Oncology (ESMO) 2019 Congress in September.

The test was created by GRAIL, Inc and uses a sequencing technology to probe the DNA for
chemical tags, called methylation, that determine if a gene is active or inactive. The test looks for DNA that cancer cells have shed into the bloodstream after they die. This is different to “liquid biopsies” which detect genetic mutations or other cancer-related changes in the DNA. The new test focuses on DNA modifications in methyl groups, which are chemical units that can be attached to DNA and control which genes are turned on or off. When methylation patterns are abnormal, it’s more likely that cancer in present.

In the study, investigators analyzed DNA that had once been inside cells but had since entered the bloodstream. In the trial, the test was used on approximately 3,600 blood samples from healthy patients and patients diagnosed with cancer. The samples came from patients with more than 20 types of cancer including colorectal, esophageal, gallbladder, lung, ovarian and pancreatic. The test was able to detect a cancer signal from blood samples that came from cancer patients and also identified where the cancer originated in the body.

The trial results were 99.4% correct, meaning the results incorrectly found that cancer was
present less than 1% of the time. Investigators pre-specified a set of cancers with high mortality rates and found that the test was also able to correctly identify these cancers. The test was better able to identify the cancers at later stages with its ability to detect cancer as follows: 32% of stage I cancers, 76% of stage II cancers, 85% of stage III cancers and 93% of stage IV cancers. The test was also able to return a result regarding the tissue of origin for 97% of the samples and correctly identified the location in 89% of cases.

While further development of the test is needed to improve its ability to detect early-stage
cancers, most cancer patients whose cancer is caught at an earlier stage have augmented
chances of long-term survival.

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