Fecal immune test can be a colon cancer detector

Dear Dr. Roach: Iama 74-year-old male, and I received a negative result from my mail-in fecal test. I have been on an every-five-years colonoscopy cycle for the past 20 years (noncancerous polyps were always found) and since my colorectal surgeon retired, I decided to use the FIT. Since then, I have been told that the FIT is not reliable for those on my cycle. With my insurance plan, I would be paying the full colonoscopy cost if polyps are found (no cost if no polyps, since it is considered a different procedure). My question is: Can I rely on the FIT results? — R.D.

Dear R.D.: A FIT test is a fecal immunochemical test for blood. It is superior to the standard guiaic tests (stool cards) that have been done for many years because it can find more cases of colon cancer, and has no more false-positive tests.

Because it is quite sensitive, a negative test means it is unlikely you have colon cancer. One study estimated that in an average-risk population, a person with a negative FIT test is 94% likely NOT to have any kind of advanced precancerous polyp and 99.9% likely not to have colon cancer.

In the U.S., FIT tests are usually used every year, while in other countries, every two to three years is common. I cannot comment on what your insurance plan will pay for, but repeatedly negative FIT tests are good evidence that you do not have colon cancer. The colonoscopy remains the most commonly recommended choice for colon cancer screening, but FIT tests or combination FIT and genetic tests are a reasonable choice for people who do not want colonoscopy or who are not good candidates.