Fecal screening tests for colorectal cancer may not have the last word, Elizabeth Tracey reports

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Fecal immunochemical or FIT tests are increasingly being used to screen for colorectal cancer, with a recent study examining just how good – or not – they are at doing so. Kimmel Cancer Center director William Nelson at Johns Hopkins looks at their performance.

Nelson: If you have a negative test how likely is it to be negative? And if you have a positive test how likely is it to be positive? The negative predictive values for almost all of them was well into the 90% range. The positive predictive value was in the 20% range. What that means is that if you have a positive test you only have about a 20 to 29% chance of actually being positive. You'll need to do colonoscopies so it's not as perfect a test as the gold standard colonoscopy.    :31 

Nelson notes that these tests are more predictive the more times they are performed, so if you do such a test yearly your odds of avoiding colorectal cancer improve, yet right now, there is no substitute for colonoscopy. At Johns Hopkins, I’m Elizabeth Tracey.