STEVE INSKEEP, HOST:
And we're also tracking news from the world of science. One day there could be a simple blood test to help diagnose and track cancers. We're not there yet but research in this area shows we're getting closer. In the latest of these studies scientists have used blood samples to identify people with lung cancer. NPR's Richard Harris explains how they're doing it.
RICHARD HARRIS, BYLINE: At the Stanford School of Medicine, Dr. Max Diehn spends some of his time treating patients with cancer and some of his time delving into the world of DNA - in particular, he's been working on ways to detect DNA that has been shed from a tumor and ends up in a patient's blood.
MAX DIEHN: The problem has been that there's a very small amount of that DNA there, usually. So it's very hard to detect. It's like trying to find a needle in a haystack.
HARRIS: But new technologies allow him to find tiny amounts of DNA and scan large parts of it to look for mutations that come from tumors.
DIEHN: The initial impetus was having something I could use in the clinic on my own patients and of course on other people's patients, too, eventually as a blood test that would let us both detect the presence of cancer as well as monitor how a patient's cancer responds to various treatments.
HARRIS: Right now, doctors often just wait and hope for months or even years to see whether a cancer treatment has worked. But Diehn and his colleagues say they've developed a super-sensitive DNA test that can tell them right away whether there is tumor left in a patient.
DIEHN: If there is cancer DNA in the body left, that suggests there are still cancer cells left, so that patient is probably not cured. Whereas if the cancer DNA is gone then that suggests the patient is likely to be cured.
HARRIS: And if the cancer is still there, they can try other treatments. Their new experimental test is specific for lung cancers. They report in Nature Medicine that they were able to detect tumor DNA in every patient they studied who had a more advanced cancers, Stage 2 or higher. And, more remarkably, they have been able to detect very early Stage 1 lung cancer about half of the time with a test they still haven't perfected.
DIEHN: Now since we can already detect half of them with the current assay, we're very hopeful that the majority of cases will have detectable DNA.
HARRIS: They're working on making the lung cancer test find more tumors and they're also working on similar tests for all sorts of other cancers. Diehn's colleague, Dr. Ash Alizadeh, says those include lymphomas, cancers of the breast, esophagus and pancreas.
ASH ALIZADEH: But the ultimate holy grail would be to move this to the early detection of cancers where the cancer detection early could save many lives by being amenable to being treated.
HARRIS: And they aren't the only lab on that quest. Dr. Luis Diaz and colleagues at the Johns Hopkins School of Medicine recently reported a blood DNA test targeting 14 different tumor types. The Hopkins team also found about half of the early-stage cancers in their volunteers. Diaz says even a test that only finds early stage cancer half the time is still a big step forward.
LUIS DIAZ: When you have a Stage 1 tumor, the patients feel healthy. They're still going to the gym, they're still performing all their activities of daily living without any sort of feeling that something's wrong. This blood test will detect the cancer at a very early stage, albeit only in 50 percent of cases.
HARRIS: The researchers are optimistic they can improve the test so it will catch many more cases. But they don't yet know whether that's a matter of better technology or if some tumor DNA will simply always remain hidden. But even as it is, this emerging DNA technology has many uses.
DIAZ: For me, this is very exciting because there is momentum building in this field, and with many groups beginning to work on this, many groups capable of doing this highly sensitive, highly specific digital genomics, what we're going to see is really cool questions answered that we couldn't have answered in any other way.
HARRIS: And while new medical technologies often drive up the cost of care, these researchers say they hope that a few years from now a cancer blood test will be available for one or two hundred dollars. Using it could help patients avoid costly scans and late diagnoses when cancer is often more difficult and more expensive to treat.
Richard Harris, NPR News.
(SOUNDBITE OF MUSIC)
INSKEEP: Thanks for joining us each day on your public radio station. Remember, you'll find ALL THINGS CONSIDERED on the radio later and we're with you online. You can still find Borderland, a digital magazine of stories, stats and amazing pictures from our trip along the U.S./Mexico border. It's at npr.org. Or just do a search for NPR Borderland; it comes right up.
You're listening to MORNING EDITION from NPR News.