FDA approves colon cancer blood test, but some will still need colonoscopies

The Food and Drug Administration provided final approval on Monday for a new colorectal cancer screening that could provide an alternative to traditional colorectal cancer screenings.

Guardant Health's Shield blood test is now an approved screening option for adults over age 45 with an average risk of colorectal cancer. It is the first blood test approved as a primary screening option for the cancer, the company said.

Currently, health officials recommend that adults over age 45 with an average risk of colorectal cancer either provide a stool sample every 1-3 years or have a colonoscopy every decade. The American Cancer Society, however, notes that over 40% of Americans over age 45 are not up to date with screenings.

Guardant Health says that its blood test gives patients a less invasive option that might help increase the number of people who get screened for colon cancer. The company says that a screening can be conducted using a simple blood draw.

“The persistent gap in colorectal cancer screening rates shows that the existing screening options do not appeal to millions of people,” Daniel Chung gastroenterologist at Massachusetts General Hospital, said in a statement. “The FDA's approval of the Shield blood test marks a tremendous leap forward, offering a compelling new solution to close this gap. This decision will help make screening tests more broadly accessible and propel blood-based testing and CRC screening into a new era. With increased screening rates and early cancer detection, many more lives can be saved.”

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According to the American Cancer Society, 1 in 23 men and 1 in 25 women will be diagnosed with colorectal cancer in the U.S.

Early detection is key for surviving colorectal cancer, experts say. According to the American Cancer Society, those diagnosed with colon cancer before it spreads to other parts of the body have a five-year survival rate of 91%. However, when cancer has spread to distant parts of the body, such as the liver, lungs, or distant lymph nodes, the survival rate drops to 13%.

The new blood test does have a drawback with its accuracy. More than one out of every 10 tests had a false positive. A colonoscopy would also be necessary if the blood test detects cancer, which would provide doctors with more details on how to treat the patient.