Colorectal cancer is the third most common cancer diagnosed in both men and women each year in the United States. There are screenings that are used to look for cancer before a person has any symptoms or signs. Whether it's making an appointment for a colonoscopy or deciding among home-based tests such as Cologuard or FIT testing, selecting a colon cancer screening tool for patients has become more complex than it used to be.
What Is A Colonoscopy?
A colonoscopy allows the doctor to look inside the entire rectum and colon while a patient is sedated. A flexible, lighted tube called a colonoscope is inserted into the rectum and the entire colon to look for polyps or cancer.
Physicians who perform colonoscopy still regard colonoscopy as the gold standard since it has the highest detection rate of small tumors and polyps.
"This is an important but underappreciated benefit of colonoscopy," said Ben Tsai, MD, a colorectal surgeon with Franciscan Physician Network Indiana Colon & Rectal Specialists in Indianapolis. "With colonoscopy, we are able to completely remove polyps or biopsy suspicious lesions."
Cologuard is a new, stool-based test and also can be known as the fecal immunochemical test (FIT). These stool-based tests can be done at home have a much higher sensitivity and specificity for colon cancer. The Cologuard test determines if there is blood in your stool, if there are precancerous polyps, or abnormal DNA.
According to Cologuardtest.com, there is no special preparation needed to prepare for this test, just following the instruction that arrived with the Cologuard kit. This includes not needing to stop any medication prior to collecting a sample.
Cologuard test results
Your Cologuard test results will typically be delivered to your healthcare provider within two weeks of the Cologuard lab receiving a sample.
These stool-based tests are limited in their ability to detect polyps, and they do not differentiate between cancer and benign polyps. This can result in a positive stool test that creates unnecessary worry.
In addition, if the stool-based test turns out positive, the next step for the patient is to have a colonoscopy to rule out cancer. A positive Cologuard test means that DNA and/or hemoglobin biomarkers that are associated with colorectal cancer were detected in the stool.
A negative Cologuard test means that Cologuard did not detect significant levels of DNA and/or hemoglobin biomarkers in the stool that are associated with colorectal cancer.
FIT testing is recommended annually, and Cologuard every three years if testing is negative, but positive test results require a follow-up with colonoscopy.
False positives and false negatives occur with Cologuard, so appropriate follow-up is important.
A false positive, or the stool-based cancer screening coming back positive when everything is completely normal, can occur.
Interestingly, foods you eat may contibute to this. Foods triggering false alarms and leading to additional testing include:
- red meat
Why Use A Cologuard Test For Colon Cancer Screening?
Because the stool-based tests are easier to complete, many patients opt for this method since some type of colorectal cancer screening is preferred to none at all. Current estimates suggest that 70 percent of eligible patients get a colon cancer screening of any kind.
"Some patients may choose to forego screening altogether if stool-based testing is not offered," said Paul Broderick, DO, with Franciscan Physician Network Central Indiana Proctology in Martinsville. "The need for bowel prep, sedation and the costs and logistics of an outpatient procedure can be significant deterrents."
Do I Need Both A Cologuard Test And A Colonoscopy?
Cologuard and a colonoscopy test for similar things, but they take two different approaches to detecting colorectal cancer.
Michael Morelli, MD, of Indianapolis Gastroenterology & Hepatology, noted there is no need to combine colonoscopy and stool-based tests. Dr. Morelli is an independent provider who chooses to practice at Franciscan Health.
"There is no benefit to FIT or Cologuard testing in an average-risk patient who has had a normal colonoscopy within 10 years," Dr. Morelli said. "Doing so only adds to the overall cost of screening and may result in unnecessary follow-up tests."
Cologuard Vs. Colonoscopy: Which One?
Physicians who work in the field largely regard colonoscopy as the gold standard. Colonoscopy has the highest detection rate of small tumors and polyps, and It is the cancer screening that can prevent colon cancer by removing precancerous polyps.
"By removing polyps this can prevent a cancer from growing, and this is one of the best cancer prevention methods we have," said Peter Garrett, MD, a radiation oncologist with Cancer Care Group in Indianapolis. Dr. Garrett is an independent provider who chooses to practice at Franciscan Health.
Colonoscopy remains the first recommendation for all eligible, average-risk patients, and stool-based testing if patients are unwilling to proceed with colonoscopy initially. High-risk or symptomatic patients should undergo colonoscopy without stool-based testing. Insurance often covers screening colonoscopies, but if an abnormality is found, it becomes a diagnostic colonoscopy, which may be more expensive per your plan.
It's also important to remember that most insurance companies will only cover one colon cancer screening test. If a stool-based test is positive, the follow-up colonoscopy may be considered diagnostic and fall under the patient's deductible. This is important to know because the false positive rate (test coming back positive when everything is completely normal) is about 13%. Foods like red meat, beets, broccoli, cantaloupe, carrots, cauliflower, cucumbers, grapefruit, horseradish, mushrooms, radishes and turnips can all trigger false alarms and could lead to unnecessary additional testing.
Stool-based tests do not differentiate between cancer and benign polyps, and a positive stool test can create confusion for patients. Some of these positive test patients will have completely normal colonoscopy exams; some will have polyps that are easily removed with colonoscopy; and a small fraction will have cancer. Cologuard is quite accurate in detecting if you have colon cancer but only about 42% accurate in detecting if you have polpys. Polyp removal is the key to colon cancer prevention so Cologuard could end up falling short in this area.
What matters most is that all patients undergo age-appropriate colon cancer screening of some type and adhere to routine surveillance depending on their specific circumstances.
Get the facts about colonoscopy. Download a free guide or watch a video from one of our experts as they discuss the facts about the screening and its importance in preventing and detecting colorectal cancer in its early stages.
By Ariel Anderson
Social Media Specialist