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 tumor 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 Nov. 28 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 specialized bioinformatic approaches, they were able to detect these alterations in a small fraction of the millions of DNA sequences contained in the blood sample.
"This is proof of the principle that genome sequencing to identify chromosomal alterations may be a helpful tool in detecting cancer DNA directly in the blood and, potentially, other body fluids," says Rebecca Leary, a postdoctoral fellow at Johns Hopkins. "But larger clinical trials will be needed to determine the best applications of this approach."
The investigators note that there may be less circulating DNA in early stage cancers, and, thus, these would be more challenging to detect without more extensive sequencing. As sequencing costs decrease, the investigators expect that detecting earlier-stage cancers may become more feasible.
Velculescu says that additional research will focus on determining how the new test could help doctors make decisions on treating patients. For example, the blood test could identify certain chromosomal changes that guide physicians to prescribe certain anti-cancer drugs or decide patient enrollment in clinical trials for drugs that target specific gene defects. Currently, physicians use cellular material biopsied from the original tumor to make these decisions, but tumor material can often be inaccessible or unavailable.
The Johns Hopkins study builds on the team's earlier work using genomic sequencing of DNA in the blood to find rearrangements of chromosomes. The previous work required samples of the original tumor and knowledge of DNA changes in that tumor to find those same changes in the blood. This new test has no need for original tumor samples and includes an analysis of changes in the copy number of chromosomes.
"It's an evolution of technologies we're developing for cancer diagnosis, and, by combining our knowledge, we can build better ways to detect disease," says Luis Diaz, M.D., an oncologist and director of the Swim Across America laboratory at Johns Hopkins.
Johns Hopkins Medicine: http://www.hopkinsmedicine.org
This press release was posted to serve as a topic for discussion. Please comment below. We try our best to only post press releases that are associated with peer reviewed scientific literature. Critical discussions of the research are appreciated. If you need help finding a link to the original article, please contact us on twitter or via e-mail.
In 1919 "Little Albert" was conditioned to fear harmless animals in an infamous experiment. Now it looks as if we've solved the mystery of his later life
As long as the African epidemic continues unabated, researchers warn that the risk to countries in Europe and elsewhere will keep rising
Instead of brooding over a failed relationship, psychologist advises a couple of aspirin and distancing oneself from the event
Brazilian researchers release thousands of mosquitoes infected with a bacteria that suppresses dengue fever into the environment in Rio de Janeiro.
Major food companies have cut trillions of calories, and studies show Americans are consuming fewer calories because of it. But some advocates think companies should do more to improve our diets.
The National Institutes of Health is providing $10 million to explore sex difference in disease, part of a move to boost female numbers in clinical trials
The World Health Organization warns of more than 20,000 cases by early November if help doesn't arrive quickly in West Africa. The CDC projects 1.4 million cases by late January.
When you're paid to hit people, it's not always easy to stop at the end of the work day—a fact the NFL has to reckon with, and fast
Is Democracy a key to better levels of health in a country? That's long been the belief, but we hear about some research that shows that isn't always the case.
You can learn a lot about people if you mess with their minds. Here are four infamous experiments in which psychologists gave in to unethical temptations