The Galleri blood test is being now offered by a number of United States health networks.
The company marketing the test, GRAIL, has established partnerships with the U.S. Department of Veterans Affairs, Mercy Health, Ochsner Health, Intermountain Healthcare, Community Health Network, Knight Cancer Institute at Oregon Health & Science University, Premier, and Cleveland Clinic, among others.
Cleveland Clinic’s Eric Klein, MD, emeritus chair of the Glickman Urological Kidney Institute, is enthusiastic about the test, describing it as a “game-changer” and emphasizing that it can detect many different cancers and at a very early stage.
“It completely changes the way we think about screening for cancer,” commented Jeff Venstrom, MD, chief medical officer at GRAIL. He joined the company because “there are not many things in life where you can be part of a disruptive paradigm and disruptive technology, and this really is disruptive,” he said in an interview.
‘The devil is in the details’
But there is some concern among clinicians that widespread clinical use of the test may be premature.
Having a blood test for multiple cancers is a “very good idea, and the scientific basis for this platform is sound,” commented Timothy R. Rebbeck, PhD, professor of cancer prevention, Harvard T.H. Chan School of Public Health, and Division of Population Sciences, Dana-Farber Cancer Institute, both in Boston.
“But the devil is in the details to ensure the test can accurately detect very early cancers and there is a pathway for subsequent workup (diagnosis, monitoring, treatment, etc.),” Dr. Rebbeck told this news organization.
Galleri is offering the test to individuals who are older than 50 and have a family history of cancer or those who are high risk for cancer or immunocompromised. They suggest that interested individuals get in touch with their health care professional, who then needs to register with GRAIL and order the test.
As well as needing a prescription, interested individuals will have to pay for it out of pocket, around $950. The test is not covered by medical insurance and is not approved by the U.S. Food and Drug Administration.
Falls into primary care setting
Dr. Rebbeck commented that Galleri is a screening test for individuals who don’t have cancer, so the test is intended to fall into the primary care setting. But he warned that “clinical pathways are not yet in place (but are being developed) so that primary care providers can effectively use them.”
The test uses next-generation sequencing to analyze the arrangement of methyl groups on circulating tumor (or cell-free) DNA in a blood sample.
The methylation turns genes on or off, explains Cleveland Clinic’s Dr. Klein in his post. “It’s like fingerprints and how fingerprints tell the difference between two people,” he wrote. “The methylation patterns are fingerprints that are characteristic of each kind of cancer. They look one way for lung cancer and different for colon cancer.”
The test returns one of two possible results: either “positive, cancer signal detected” or “negative, no cancer signal detected.”
According to the company, when a cancer signal is detected, the Galleri test predicts the cancer signal origin “with high accuracy, to help guide the next steps to diagnosis.”
However, one problem for clinical practice is all the follow-up tests an individual may undergo if their test comes back positive, said Sameek Roychowdhury, MD, PhD, an oncologist with Ohio State University Comprehensive Cancer Center, Columbus.
“Not everybody will have an actual cancer, but they may undergo many tests, with a lot of stress and cost and still not find anything. I can tell you every time someone undergoes a test looking for cancer, that is not an easy day,” Dr. Roychowdhury said in an interview.
In a large-scale validation study, the Galleri test had a specificity of 99.5% (false-positive rate of 0.5%), meaning in roughly 200 people tested without cancer, only one person received a false-positive result (that is, “cancer signal detected” when cancer is not present).
The overall sensitivity of the test for any stage of cancer was 51.5%, although it was higher for later-stage cancers (77% for stage III and 90.1% for stage IV) and lower for early-stage cancers (16.8% for stage I and 40.4% for stage II).