FDA approves new blood test for colorectal cancer screening

A new blood test to screen for colon cancer was approved by the Food and Drug Administration on Monday, aimed at finding cancer when it’s still in the early stage and treatable. 

The blood test, known as Shield and manufactured by Guardant Health, has been on the market since 2022, but was not widely covered by private insurance so patients have often needed to pay the entire $895 cost out-of-pocket. FDA approval is likely to increase coverage and access. 

Shield is available for eligible individuals by prescription through a doctor or other healthcare professional and is expected to be covered for eligible Medicare beneficiaries. It was approved for people aged 45 and older with an "average risk" of colon cancer. 

Colorectal cancer is the second-leading cause of cancer-related death in the U.S., even though it is highly treatable if caught early.  

Shield is the first blood test approved by the FDA as a primary screening option for colorectal cancer, the manufacturer said.  

It’s also the first approved blood screening test for colorectal cancer that meets requirements for Medicare reimbursement. 

According to the American Cancer Society, when colon cancer is found at an early stage before it has spread, the five-year relative survival rate is 91 percent. If the cancer has spread to distant parts of the body, the five-year relative survival rate is 14 percent. 

Current guidelines recommend screenings starting at age 45, but more than one out of three eligible Americans – over 50 million people – do not complete screening, often due to the perception that other available options, such as colonoscopy or stool-based tests, are invasive, unpleasant or inconvenient. 

According to the company, the overall adherence rate for the Shield test has been more than 90 percent. In contrast, studies show only 28-71 percent of patients who are prescribed other screening methods, such as colonoscopy or a stool test, complete them. 

“This is a promising step toward making more convenient tools available to detect colorectal cancer early while it is more easily treated,” William M. Grady, a gastroenterologist at Fred Hutchinson Cancer Center, said in a statement Monday released by Guardant Health.  

Grady in the statement said the test has an accuracy rate similar to stool tests used for early detection of cancer. 

But the test has a drawback: based on data from clinical studies, Shield has limited detection of Stage I colorectal cancer and does not detect 87 percent of precancerous lesions. It was much better at detecting later stage cancers.  

The test relies on detecting DNA shed by tumors into the blood stream, so the bigger the tumor, the more DNA it releases.  

If the results indicate cancer is present, patients still need a colonoscopy so doctors can see where tumors are and how far they’ve progressed, the company said.