On two previous occasions, I have written blogs about the MCED (Multi-Cancer Early Detection) test known commercially as the Galleri test. The test was developed, and is marketed, by a San Francisco-based biotechnology company called Grail, Inc. In October, 2022, when I first wrote about the test, I was very enthusiastic and optimistic about its future prospects. Grail purported Galleri would, or could, detect 50 types of cancer in adults age 50 years and older. From a simple blood sample, and $949, Galleri was able to tell if you had cancer.
The second article, published May 12, 2025, was titled “What is the Galleri Test?” In this blog, I reported on heavy skepticism and concern about the Galleri test that had come about because of claims made by the European division of Grail. They were over-hyping the value of the test and were being challenged by experts’ criticism and unverifiable value.
On July 24, 2025, Medscape published a “Commentary” by Kenneth W. Lin MD, associate director of the Lancaster General Hospital Family Medicine Residency, blogger, and frequent contributor to American Family Physician, the scientific journal of the American Academy of Family Physicians. The article, titled “MCED Tests in Primary Care: Proceed With Caution,” reported exactly the same concerns I expressed in my May blogpost.
Grail touts the Galleri test’s ability to detect 50 types of cancer, and although it is highly specific for detecting cancer, the sensitivity for detecting early stage cancers is low. To put it plainly, the Galleri test will detect/find a cancer if it’s there, BUT it won’t/cannot find it earlier than standard screening methods. Nor does it find it in a stage early enough to impact statistics on cancer deaths. In a huge trial of 140,000 patients in the UK, Galleri failed, thus far, to meet early detection expectations and impact cancer deaths. That’s not good! “To be effective, MCED tests must accurately detect cancer in asymptomatic people at stages early enough to avoid toxic chemotherapy and allowing patients to live longer or better.”
The American Cancer Society has issued a statement to guide family doctors in using the Galleri test. The ACS is concerned about the benefits and emphasizes that even with negative results, patients still need to have all recommended screenings. Patients with positive Galleri tests need to have diagnostic tests for the predicted tissue/organ of origin as well as a total body PET-CT scan. The Galleri test is just a starting point and should not be thought of as the final answer, even if it is negative. As mentioned, if it is negative it does not give you a “clean bill of health.” Its low sensitivity translates into “don’t rest on your laurels.” Keep a sharp eye out, and be diligent in following routine screening protocols. All the stats report it does not improve early detection or improve cancer deaths, so don’t over-anticipate benefit.
Dr. G’s Opinion: For $949, this test is not for everyone. But people who want it and can afford it, can have it. It is not reliable enough, though, to be a mandated part of a wellness check! I personally would not waste my money. All that I read about Galleri places me in the skeptic’s column. Save your money and have a colonoscopy and all the other recommended screening tests. I think that’s money better spent.
Reference: Lin KW. “MCED Tests in Primary Care: Proceed With Caution” Medscape 2025 July 24.
