Blood Test Now Approved for Colon Cancer Screening

Getting screened for colon cancer just became a lot easier for people who've been putting it off.

The American Cancer Society announced this week that a blood test is now an approved screening option for adults 45 and older at average risk for colorectal cancer. It's the first time a blood test has made the list of recommended screening methods, joining colonoscopies and stool-based tests.

The Shield blood test, approved by the FDA in 2024, works by detecting tumor DNA in a simple blood sample. For many people, this is welcome news after years of avoiding screening because they didn't want a colonoscopy or weren't comfortable with stool collection tests.

The timing couldn't be more critical. One in three eligible adults still hasn't been screened for colorectal cancer, even as it becomes the leading cancer killer among Americans under 50. When caught early through screening, more than 90% of people with stage I or II colorectal cancer survive at least five years.

Dr. William Dahut, chief scientific officer for the American Cancer Society, sees this as a game changer for reluctant patients. "There are a lot of people who can't or won't do a colonoscopy," he said. "Having more options hopefully will allow more people to be screened to find cancers earlier on."

The blood test isn't perfect. It catches 83% of colorectal cancers but is less effective at detecting precancerous polyps than colonoscopies or stool tests. That's why doctors still recommend it only for people who decline or don't complete the other screening options.

The Bright Side

This recommendation represents a major shift in how we think about cancer screening. Instead of leaving people unscreened because they won't do the "gold standard" test, doctors now have another tool to meet patients where they are.

Two new at-home stool tests also made the updated guidelines: Cologuard Plus and ColoSense. Both can be done at home and mailed to a lab, making screening even more convenient.

Experts believe this is just the beginning. More blood-based tests are in development, with better accuracy expected as the technology improves. For now, thousands of lives could be saved simply by giving people a screening option they'll actually use.

Early detection through screening also prevents cancer entirely by catching precancerous polyps before they turn dangerous.