By Durado Brooks, MD
Has your doctor ever talked to you about collecting part of your bowel movement to be examined (referred to as a "stool test")? If you're anything like the patients I've treated, you recoiled in shock and horror! The idea just sounds disgusting, doesn't it? Without getting too technical, stool tests have what we doctors call a high YUCK factor. (No, it's not an acronym; it's what patients say when we ask them to do the test: "Are you kidding, doc? Yuck!")
But stool tests are one of the tried and true approaches to finding colorectal (colon) cancer early and saving lives. There are a number of different tests for colon cancer that are recommended by the American Cancer Society and other organizations, including colonoscopy, flexible sigmoidoscopy, and CT colonography (a special type of x-ray test, sometimes called "virtual colonoscopy"). But the fact is, out of all the tests that are recommended for colon cancer screening, stool tests actually have the strongest evidence that they save lives - a fact that most patients (and many doctors) don't appreciate.
How the FOBT Works
There are different types of stool tests, but the ones that have been around for the longest time and have the best scientific evidence work by finding microscopic amounts of blood in the stool. These tests are known as Fecal (another word for "stool") Occult Blood (which means "hidden blood") Tests, commonly abbreviated as FOBTs.
|As you may know, most colon cancer starts as a non-cancerous growth called a polyp. Not all polyps will progress to cancer, but for those that do, the transformation usually takes a number of years. Many cancers (and some polyps) bleed, but the amount of bleeding in most cases is small, and when mixed with the stool becomes invisible to the naked eye. To check for this blood, patients must collect a small sample from one or more bowel movements (depending on the brand of test used). This sample is then sent or taken to a lab or to the doctor's office where it is exposed to a chemical reaction that indicates whether blood is present.
What Happens After the FOBT
When blood is found in a stool sample it is referred to as a "positive FOBT." Fortunately, most patients with a positive FOBT do not have cancer. Most positive FOBTs result from common, non-cancerous problems in the stomach or bowel - things like ulcers, diverticulosis, or hemorrhoids. However, even if you know that you have one of these problems, you should never assume that these are the cause for a positive FOBT. If you have a test that shows blood in your stool you need to have a colonoscopy; you don't want to take a chance on missing a polyp or cancer.
It is also important to keep in mind that a rectal exam IS NOT an acceptable colon cancer screening method. It was once believed that the rectal exam (when the doctor inserts a gloved, lubricated finger into the patient's rectum) helped to find colon cancer. Doctors would combine a rectal exam with a single sample stool test in their office. However, research has shown that this approach is almost worthless and will miss more than 9 out of 10 polyps and cancers. While there are still some reasons for doctors to perform rectal exams, colon cancer screening is not one of those reasons.
The American Cancer Society recognizes several acceptable options for colon cancer screening. If you are 50 or older and your doctor has not talked to you about colon cancer screening, ask your doctor which of these tests is right for you. If someone in your family had colon cancer, ask your doctor about testing even if you aren't 50 yet. And if your doctor recommends stool testing - Just Do It! Get past the "yuck!"
Dr. Brooks is director of prostate and colorectal cancers for the American Cancer Society.