Scientists pair blood test and gene sequencing to detect cancer

Scientists at the Johns Hopkins Kimmel Cancer Center have combined the ability to detect cancer DNA in the blood with genome sequencing technology in a test that could be used to screen for cancers, monitor cancer patients for recurrence and find residual cancer left after surgery.

"This approach uses the power of genome sequencing to detect circulating tumour DNA in the blood, providing a sensitive method that can be used to detect and monitor cancers," says Victor Velculescu, M.D., Ph.D., professor of oncology and co-director of the Cancer Biology Program at Johns Hopkins.

A report describing the new approach appears in the 28 November issue of Science Translational Medicine. To develop the test, the scientists took blood samples from late-stage colorectal and breast cancer patients and healthy individuals and looked for DNA that had been shed into the blood.

The investigators applied whole-genome sequencing technology to DNA found in blood samples, allowing them to compare sequences from cancer patients with those from healthy people. The scientists then looked for telltale signs of cancer in the DNA: dramatic rearrangements of the chromosomes or changes in chromosome number that occur only in cancer cells.

No signs of cancer-specific chromosome changes were found in the blood of healthy individuals, but the investigators found various cancer-specific alterations in the blood of all seven patients with colon cancer and three patients with breast cancer.

Using specialised bioinformatic approaches, they were able to detect these alterations in a small fraction of the millions of DNA sequences contained in the blood sample.