The new colon cancer blood test misses most polyps

The approval landed on July 27. SimpleScreen CRC looks for cell-free DNA signals associated with colorectal cancer in an ordinary blood sample. Freenome developed the test and Abbott will commercialize it in the US this fall, for adults 45 and older at average risk who come in with a provider referral.

The validation study was unusually well designed. PREEMPT CRC enrolled more than 48,000 asymptomatic average-risk adults aged 45 to 85 across over 200 sites. Every participant was already scheduled for a screening colonoscopy, so each blood result could be checked against what the scope found in the same person.

It catches cancer that is already there. Sensitivity for colorectal cancer came in at 81.1%, with 90.4% specificity for advanced colorectal neoplasia. Four out of five cancers present at the time of the draw showed up in the blood.

It rarely catches the growth before it turns. Sensitivity for advanced precancerous lesions was 13.7%. For the subset carrying high-grade dysplasia, the ones closest to becoming cancer, it reached 30.7%. A colonoscopy finds those growths and removes them during the same appointment. That removal is how colonoscopy prevents colorectal cancer rather than detecting it.

Every positive result still ends at a colonoscopy. Freenome's indication says so plainly. The value of a blood-based screen sits in the people who would otherwise decline screening altogether, and there are many of them. For someone already willing to book the scope, swapping it for a blood draw trades away the part that removes the polyp.

This is the second test with this profile, not the first. The FDA approved Guardant Health's Shield in July 2024. NCI reported it detected colorectal cancer in more than 83% of participants who had it, and advanced adenomatous polyps only about 13% of the time, with a positive result still requiring a colonoscopy. Two approvals apart, the same trade-off held.