Early-stage tumor specific DNA has been identified in more than half of 138 patients with the disease, researchers reported – new milestone in the area of “liquid biopsy”
There are several companies that already offer tests that are able to detect cancer DNA in the blood of patients who suffer from late-stage cancers. These kind of tests are used to guide treatment or identify whether cancers have returned after surgery or not.
Researchers hope that tests will soon be able to detect cancers in early-stage patients, when they have a better chance of survival.
“To our knowledge, this is one of the first studies that has looked directly at early-stage cancers,” said Dr Victor Velculescu, professor of oncology at Johns Hopkins Kimmel Cancer Center
The biggest challence in the test was identifying rare DNA from real cancers while also ignoring other types of genetic alterations that can occur when blood cells divide or simply alterations that people are born with.
For the development of the study, the team screened blood samples from patients who suffered from breast, lung, ovarian, and colorectal cancer; they further looked for 58 genes that are typically linked with these cancers. All in all, they were able to detect 86 out of 138 stage 1 and 2 cancers. Furthermore, they also sequenced mutations in tumors from 100 of the studied patients, and discovered that in 82 cases, the same mutations that were found in the blood corresponded with those found in the tumor tissue.
However, Velculescu said that more studies are needed in much larger populations in order to prove that the test can safely and accurately identify early-stage cancers; this process could take up to 5 years.