The US Food and Drug Administration (FDA) has approved a blood test that can help detect colorectal or colon cancer, expanding screening options for one of the deadliest diseases affecting young populations worldwide.

The blood test, called Shield, is manufactured by pharmaceutical company Guardant Health Inc. The FDA approval follows promising results from a clinical study published earlier this year in the New England Journal of Medicine in March.

The study found that the test correctly detected colon cancer in 83% of people who had a confirmed diagnosis of the disease. These participants were at average risk and experienced no symptoms. The Shield blood test results come from more than 10 years of research and development.

“The FDA’s approval of the SHIELD test is a significant win for patients and an important milestone in Guardant Health’s mission to conquer cancer with data,” Amir Ali Talasaz, MD, co-CEO of Guardant Health, said in a news release.

“The Shield could help improve colorectal cancer screening rates, allowing us to detect more cancers at an early stage, when they are most treatable,” Talasaz said.

According to the official statement, Shield is the first blood test to be approved by the FDA as a primary screening option for colon cancer, meaning healthcare providers can offer Shield at the same time as all other non-invasive methods recommended in screening guidelines.

“The persistent gap in colorectal cancer screening rates shows that existing screening options are underserved by millions of people. The FDA’s approval of the Shield blood test is a tremendous leap forward, offering an exciting new solution to close this gap,” said Daniel Chung, MD, a gastroenterologist at Massachusetts General Hospital and professor of medicine at Harvard Medical School.

This test uses blood collected in a Guardant Shield blood collection kit for individuals aged 45 years and older.

Patients with a positive test result should undergo colonoscopy, as this test is not a substitute for diagnostic colonoscopy or surveillance colonoscopy in high-risk individuals.

However, Shield has limited ability to detect stage I colorectal cancer (55%–65%) and misses 87% of precancerous lesions.

John Gormley, a 77-year-old business executive from Newport Beach, California, US, took a Shield blood test and his test came back positive. “A few days later the result came back positive, so (the doctor) referred me for a colonoscopy. It turned out I had stage II colon cancer. The tumour was removed and I recovered very quickly. Thank God I had that blood test,” he said.