Screening methods for certain types of cancer, particularly breast cancer and prostate cancer, can lead to early diagnosis.
However, there’s no catchall test to screen for every one of the more than 100 types of cancer that exist.
Researchers at GRAIL, a Silicon Valley healthcare company, are working on a DNA test based off a simple blood draw that can screen for multiple types of cancer at early stages.
They presented their findings earlier this month at the American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago.
In all, 1,627 participants underwent the test - 749 of whom were cancer-free and 878 who had newly detected cancer.
Researchers said the test showed encouraging results in detecting 10 different types of cancer, notably ovarian and pancreatic cancer.
However, some experts have pointed out the test failed to detect some types of cancer. They said more research is needed before any definitive pronouncements can be made.
One of the criticisms was contained in a cancer research blog about the ASCO meeting. Another was detailed in an analysis on the New Scientist website.
Nonetheless, the study’s lead researcher, as well as an outside expert interviewed by Healthline, agreed that while there’s plenty of research ahead, the test shows promise - and could one day be routinely administered by family doctors.
Dr. Eric Klein, a staff member at the Taussig Cancer Institute at Cleveland Clinic and the lead author of the study, told Healthline that advances in DNA sequencing technology make the test possible.
“The idea of developing a test like this, called liquid biopsy, is that we know that cancer sheds DNA and other molecules into the bloodstream,” he explained. “Through a blood test, you can sample, in essence, every organ because every organ puts substances into the bloodstream.”
Klein notes that there aren’t currently effective ways to conduct early screening for liver cancer, ovarian cancer, esophageal cancer, gastric cancer, and others. But the liquid biopsy could, he hopes, someday be an effective tool in detecting these cancers early on.
“I think the goal for a number of the groups studying liquid biopsy is a test that’s adequately sensitive and specific, and could be run in a primary care doctor’s or specialist’s office to potentially identify cancers early, or at least lead to additional testing that might detect cancers early,” Dr. Daniel Stover, a breast medical oncologist and translational physician-scientist at The Ohio State University Comprehensive Cancer Center, told Healthline.
Researchers said the blood test yielded some surprises that reflect well on its effectiveness.
“There were four patients who were not known to have cancer who had blood test patterns that suggested they might have cancer and two of them were in fact diagnosed with cancers that they had not previously known about in the next couple of months,” said Klein.
Stover points out that in addition to helping doctors detect and treat cancer early, the liquid biopsy provides valuable data for medical researchers.
“Building a repository of DNA data from blood from patients who have cancer is a valuable resource to the medical community and an important first step,” he said. “I remain really hopeful, but I also recognize that building a good screening test is very hard. We’ll look for increasing amounts of data in the coming months and years.
The GRAIL researchers plan to roll out larger studies in the coming months.
Klein says that 15,000 people will be enrolled by the end of the year for the next phase of research.
In the next phase, Klein says, researchers will retest, tweak, and fine-tune their original diagnostic algorithm to find the most effective and accurate way to get data from the test.
From there, the next phase of the study will expand by tenfold.
“There’s yet another study planned for 150,000 people, which would represent the kind of population who would be eligible to have this, who would show up at their primary care doctor and want to be scanned for cancer,” said Klein.
“There’s a lot more work to be done, but the goal, ultimately, is to make this available on the open market for physicians, to have this available as a screen for cancer,” he added. “We already screen for prostate and breast cancer — now we hope we’ll be able to screen for these other cancers.”
While it may be some time before doctors are able to use a liquid biopsy for early detection of cancer in their patients, research appears to be headed in the right direction, says Stover.
“Obviously, all of us would love a test that is very sensitive, very specific, and just requires a blood draw — but the hurdles remain high,” he said. “I think that catching cancers that don’t have an available screening test is really an admirable goal, and that’s where a lot of liquid biopsy work is appropriately headed.”