The recent study in the Annals of Internal Medicine is trending right now. It is a meta-analysis of 120,000 patients who had FIT testing (checks for microscopic blood in the stool) over the years. Their conclusions were that if FIT testing was done compliantly on an annual basis, it was highly effective at predicting colon cancer. So it remains, as occult blood testing has for many years, as one approved option for colon cancer screening. What is also concluded is that the sensitivity for advanced adenomas was about 40% for annual FIT. That is an important finding. It will likely encourage the already rising use of fecal stool tests. I think that is a great folly.
What is not conveyed in this study or others is that the mission to reduce colon cancer deaths is based on prevention and not early detection. Breast cancer mortality reduction has been achieved on a true “screening” basis. We look for radiographic evidence of early breast cancers that are in a curable stage. Then we can apply therapy early and effectively. The reduction in colon cancer mortality is achieved in an entirely different manner altogether and should be called colon cancer “prevention” rather than “screening.” We recognize that nearly all colon cancers arise as polyps. These polyps are growths of the colon wall that over many years have the risk of turning into cancer. Only 5% of polyps or so, turn into cancer. However, almost all cancers started out as a polyp. By finding and removing these polyps, we prevent colon cancer. Although it happens very rarely, we are not doing a screening colonoscopy expecting to find cancer. Advanced adenomas or high risk adenomas are the most dangerous of polyps. These are the ones that have registered for the race to turn into cancer. We have to get these out.
In this study, the FIT was only able to detect 40% of these. Are you willing to leave 60% of those bad boys in there? And so if the FIT is positive and one gets a colonoscopy to follow it (which is the only option once it is positive), how does one measure success? That you found a cancer? That’s exactly what happened to a friend of mine in Hawaii. Now he has stage 3 colon cancer. He did not get shared decision making into which colon cancer prevention strategy he wanted to participate in. He has in fact considered legal action.
Patients should however not fear. There is a high false positive rate. So just because the stool test is positive, don’t run around thinking that you have cancer. You don’t. But get a colonoscopy as soon as you can.