New Blood Test Offers Less Invasive Colon Cancer Screening Option

The American Cancer Society (ACS) recently announced a major update to its colorectal cancer screening guidelines, now including a blood-based test as a recommended option. This marks the first time a blood test has been incorporated into the ACS's primary screening recommendations, offering a less invasive alternative for millions of Americans.

The revised guideline, made public on Wednesday, May 27, 2026, introduces the Shield blood test for average-risk adults aged 45 and older. The announcement, originating from Atlanta, where the American Cancer Society is based, specifically targets individuals who have either declined or not completed more traditional screening methods. The move is expected to significantly boost participation in colorectal cancer screenings, a critical step in early detection and prevention.

Developed by Guardant Health, a company based in Palo Alto, California, the Shield test provides a new pathway for screening. This development follows a series of milestones, beginning with Guardant Health's founding in 2012. The ACS itself had already lowered its recommended age for initial colorectal cancer screening from 50 to 45 in 2018, a decision influenced by a concerning rise in colorectal cancer diagnoses among younger populations.

The journey to this guideline update picked up speed with the launch of a lab-developed version of the Shield test in May 2022. A pivotal moment came in March 2024 with the publication of the ECLIPSE study results in the *New England Journal of Medicine*. This extensive study, funded by Guardant Health, involved over 12,750 patients, with nearly 8,000 participants providing blood samples that were compared against colonoscopy results.

These robust findings paved the way for the U.S. Food and Drug Administration (FDA) to approve the Shield blood test in July 2024. This approval was historic, establishing Shield as the first blood test specifically cleared for primary screening of average-risk individuals for colon cancer. The official inclusion of this FDA-approved test into the ACS guidelines was then formalized and announced on May 27, 2026, a milestone Guardant Health acknowledged in a press release issued that same day.