Dr. Wy, why did you say we shouldn’t get the blood test for colon cancer a couple months ago? It was just approved by the FDA!

Ask Dr. Wy…

Richard Wyderski, MD, FACP

Dr. Wy, why did you say we shouldn’t get the blood test for colon cancer a couple months ago? It was just approved by the FDA!

I did write about multicancer detection (MCD) tests a couple months ago. This test, though, is specific for colon cancer, the second leading cause of cancer deaths in the US. It’s not as accurate as others, but it’s comparable to some of them that have been shown to save lives in people with average risk for the disease. Let’s compare it to a few of the most common other tests.

Colonoscopy: This is the most accurate test available, not only detecting 95% of cancers and advanced polyps, but also up to 90% of small polyps. Polyps can be taken out during the test before they ever get a chance to turn into cancer.

CT colonography: This test, which is much like a barium enema, can detect up to 90% of large polyps. Ask someone who’s had one how ahem pleasant it is. if it’s abnormal you still need to perform a colonoscopy.

FIT-DNA (Cologuard) and FIT: These stool tests are pretty good for finding cancers (92% for FIT-DNA and 75% for FIT) but less for advanced polyps (40-60% for FIT-DNA and for 30% for FIT).

Guardant Shield: This new test looks for cancer DNA fragments in the blood and is 83% accurate for detecting colon cancer. That means the test will miss the diagnosis 17% of the time. It only detects 13% of earlier stage polyps. But it’s easy to do!

Which should you do? Well, doing something is better than nothing, and the best test is the one that gets done. Please do something!

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