My GRAIL Test was Positive. Now What? 

Medically Reviewed By: Elizabeth O’Donnell, MD

If you have received a positive result from a GRAIL Galleri test, which is a multi-cancer early detection (MCED) blood test, you need further testing to determine if you have cancer.  

If you have a positive GRAIL test, that means the test has found a signal that is associated with cancer and requires investigation. Other screening tests, such as mammograms, also report signals that require investigation but don’t always turn out to be cancer. 

MCED tests are very new, and doctors are still learning how to manage diagnostics in response to a positive GRAIL test. If you need help with MCED test results, consider visiting a MCED clinic, such as the Dana-Farber Multi-Cancer Early Detection Clinic, which is part of the Centers for Early Detection and Interception

  • The Dana-Farber MCED Clinic is one of the first clinics in the U.S. to specialize in early detection of multiple cancers.  
  • The clinic provides patients with expert diagnostic workups in response to a positive MCED test, such as the GRAIL Galleri test.  
  • The clinic also provides follow up support for patients who turn out not to have cancer.  

“For anybody who has a positive test, we want to be their first call,” says Elizabeth O’Donnell, MD, director of the Dana-Farber MCED Clinic. “We know how to do cancer diagnostic workups. We have expertise in every form of cancer and can expedite referrals into appropriate clinics.” 

What is an MCED test? 

An MCED test is a novel type of blood test that screens for up to 50 different types of cancer, including bladder, esophageal, kidney, liver, skin, pancreatic, prostate, and certain blood cancers. The test looks for signals of cancer in the blood. Specifically, the test looks at fragments of DNA circulating in the bloodstream and scans for markers that might have come from a tumor cell.  

The test reports two readouts: 

  • The presence of a cancer signal. 
  • The predicted source of the cancer. If a cancer signal is detected, the test will report one or two most likely locations for a diagnostic cancer workup. 

Why are MCED tests being developed? 

Seventy percent of cancer cases involve types of cancers that don’t have screening tests. Cancer screening has only been available for a small number of cancers, such as breast cancer, colon cancer, cervical cancer, prostate cancer, and lung cancer in those at high risk.  

MCED tests could help improve detection for many more types of cancer. If cancer is diagnosed earlier, patients have a much better chance of cure or more successful treatment. 

“This field of early cancer detection is evolving very quickly,” says O’Donnell. “We’ve done amazing things with treatment, but we’re not curing many more people. To cure more people, we need to find cancer earlier.” 

Dana-Farber researchers have long been leaders in the scientific research making this kind of early screening possible. Dana-Farber experts helped conduct a clinical trial of the GRAIL Galleri test. Dana-Farber experts have also been part of the fundamental work enabling liquid biopsies to reveal details about cancer and are actively engaged in the emerging science of liquid biopsy for cancer detection.  

Are MCED tests considered standard screening tests? 

Not yet. The MCED test made by GRAIL is the first MCED test to be laboratory approved, meaning it has met the standards for a laboratory test. The test is not yet approved by the U.S. Food and Drug Administration and is not yet covered by health insurance.  

“Blood-based screening tests have the potential to be an exciting compliment to current standard screening tests,” says O’Donnell. “We are studying the use of MCED tests to see if they can be a more effective or complementary way to screen for cancer.”   

Note that individuals can order the GRAIL test or have their primary care physician order it. However, the test is not currently covered by health insurance. Further, if a diagnostic workup is needed, it also might not be covered by health insurance if the test was not covered. 

What do I do if my test is negative? 

A person who receives a negative test should continue with traditional recommended screening.  

Who should get an MCED test? 

The tests are intended for people who are at a higher risk of cancer, such as people over 50, people who have already been treated for cancer and might experience a recurrence, people who have a genetic risk of cancer, and people who have a strong family history of cancer. 

The tests are not intended for use in people under 21.  

In 2024, Dana-Farber is planning to open a clinical study of the GRAIL MCED test in high-risk populations of people, including people with an inherited elevated risk of cancer or a strong family history.  

About the Medical Reviewer

Elizabeth O’Donnell, MD

Dr. O’Donnell received her medical degree from Vanderbilt University. She completed her residency in internal medicine at the Beth Israel Deaconess Medical Center where she served an additional year as a Chief Resident. She completed her fellowship in hematology and oncology at Dana-Farber Cancer Institute. She is the Director of Early Detection and Prevention at Dana-Farber and an Assistant Professor of Medicine at Harvard Medical School. She specializes in plasma cell disorders with a particular interest in lifestyle medicine and patient and caregiver quality of life.