A collaborative project between scientists in the U.S., Denmark, and The Netherlands has developed a way of spotting bits of DNA in blood that derive from tumors deep in the body. The technology may allow for early detection of cancers before any symptoms arise and earlier than any other existing approach.
Though the fact that tumors shed chunks of DNA has been well known, it’s been difficult to know what mutations to look for in individual patients. False positives can be much too common if one doesn’t look specifically for tumor-related mutations, as benign mutations are way too frequent.
The team employed a technique called targeted error correction sequencing that scanned through lots of DNA fragments in the blood of a couple hundred individuals with and without cancer. It’s able to figure out which mutations are more probable to be associated with a cell being cancerous and which will probably not cause out of control cellular growth. The investigators were able to identify 62% of 138 patients with stage I and II breast, lung, ovarian, and colorectal cancers.
Though this capability would be much welcome in the clinic, the sequencing and computational requirements to do so are still much too expensive for wide adoption and the technique still has to be proven in wider studies. Nevertheless, the cost of sequencing and computing continues to drop rapidly.
Here are some of the findings from the study published in Science Translational Medicine:
“[A]mong 42 people with colorectal cancer, the test correctly predicted cancer in half of the eight patients with stage I disease, eight of nine (89 percent) with stage II disease, nine of 10 (90 percent) with stage III and 14 of 15 (93 percent) with stage IV disease. Of 71 people with lung cancer, the scientists’ test identified cancer among 13 of 29 (45 percent) with stage I disease, 23 of 32 (72 percent) with stage II disease, three of four (75 percent) with stage III disease and five of six (83 percent) with stage IV cancer. For 42 patients with ovarian cancer, 16 of 24 (67 percent) with stage I disease were correctly identified, as well as three of four (75 percent) with stage II disease, six of eight (75 percent) with stage III cancer and five of six (83 percent) with stage IV disease. Among 45 breast cancer patients, the test spotted cancer-derived mutations in two of three (67 percent) patients with stage I disease, 17 of 29 (59 percent) with stage II disease and six of 13 (46 percent) with stage III cancers.”
Study in Science Translational Medicine: Direct detection of early-stage cancers using circulating tumor DNA…
Via: Johns Hopkin…