FIT test good alternative for those who won't get colonoscopy


Dear Doctors: I’m a 72-year-old man, and I was supposed to get a colonoscopy last year. I was surprised when my insurance company sent me an at-home kit to do a colon cancer screening. It was a lot easier than a colonoscopy, but my question is, can it be accurate?

Dear Reader: The at-home test kit that you received in the mail is known as a fecal immunochemical test, or FIT. As with a colonoscopy, it is a diagnostic tool that looks for signs of colon cancer. The FIT test kit contains the materials you need to collect a small sample of stool and instructions on how to use them. You also get a pre-paid mailer to send the sample to a laboratory, where it gets tested for the presence of microscopic amounts of blood. Some people receive the results of their FIT test in a letter, and others are asked to log onto a web portal.

It’s not surprising that survey results show a decisive majority of patients agree with you in preferring the at-home FIT test to a colonoscopy. The former takes just a few minutes in the privacy of your own home. The latter involves a multi-day process.

The colonoscopy process begins with the use of a laxative solution to completely void the bowel. This allows any polyps or other abnormalities to be easily visualized. Before the procedure, the patient is given medications to help them relax, and asked to lie on their left side on an examination table. The physician then introduces a thin, flexible tube through the anus and into the rectum and colon. Known as a colonoscope, it has a tiny light and a camera, and is used to examine the length and breadth of the colon. The procedure typically takes between 30 and 60 minutes.

Elizabeth Ko, MD and Eve Glazier, MD
Due to the COVID-19 pandemic, diagnostic screening tests were routinely canceled. During this time, some insurance companies and health care providers closed the gap by switching to the use of FIT tests. Studies show that, for someone of average risk, the FIT test is a good alternative to colonoscopy. There is also evidence that people unwilling to undergo a colonoscopy will complete a FIT test. Considering that only half of adults stick to the suggested colon cancer screening schedule, and 30% skip screening altogether, the FIT option is beneficial.

As for accuracy, the data are still being collected. As we mentioned, the FIT test detects blood in the fecal sample. If the test comes back positive for the presence of blood, the individual is then asked to follow up with a colonoscopy. However, it’s possible for polyps to be present in the colon but to not be bleeding at the time that the test is taken. That would lead to a negative test result. On the flip side, the FIT test is also prone to false positives, which trigger the need for a follow-up colonoscopy. Depending on your own health and your personal medical history, it’s a good idea to discuss your future colon cancer screening strategy with your health care provider.

(Send your questions to [email protected], or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)