But in recent years, some in the medical field have been calling for a change in tactic. They say there are equally effective tests available that are less invasive and less of an ordeal than a colonoscopy.
In particular, they’re concerned the cost and hassle of a colonoscopy is discouraging people from being screened for colon cancer.
“You should get screened, but there are excellent screening options available in addition to colonoscopy,” said Dr. James Allison, an emeritus professor at University of California, San Francisco, who has worked in the field of gastroenterology for 40 years.
Screening for colorectal cancer can save lives
Colorectal cancer is the second leading cause of cancer death in the United States. The Centers for Disease Control and Prevention (CDC) reports that colon cancer killed more than 52,000 people in the United States in 2015.
However, it’s generally a slow-growing cancer that is treatable, if it’s caught early enough. That’s where colonoscopies and other tests come in.
Between 2014 and 2016, the number of U.S. adults being screened each year increased by 3.3 million.
In a presentation in early March of 2015, as part of Colorectal Cancer Awareness Month, the American Cancer Society announced an industry-wide goal of increasing colorectal cancer screening rates in the United States to 80 percent by the end of 2018. They estimated that would prevent 21,000 deaths from colon cancer every year by 2030.
A survey of 997 middle-aged adults published in Internal Medicine News revealed that only 38 percent of those advised by a primary care doctor to get a colonoscopy did so. That compares to 67 percent who went forward when advised to do a stool-based test.
“We will not get there on colonoscopies alone,” Wender said.
Why people hate colonoscopies
Allison and Wender both say people’s unwillingness to submit to a colonoscopy is a major reason for the low screening rate.
One of the reasons for the nonparticipation is obvious. The test is invasive and unpleasant.
In this procedure, a doctor inserts a long, flexible tube called a colonoscope into the colon and looks for polyps. If a polyp is found, it can be removed using a wire loop passed through the colonoscope. The patient is usually sedated during the exam.
There’s also the uncomfortable 24 hours before the procedure.
The colonoscopy recipient spends more than a day on a bland diet, then a liquid diet. Then they drink a gallon or so of a solution designed to clean the colon from the inside by inducing intense diarrhea.
“People say ‘I feel fine, why should I go through such an unpleasant test,’” said Wender. “You can talk yourself out of it.”
However, the unpopularity of the test stems from more than the procedure itself. People getting a colonoscopy need to take at least one day off work. They also need to find someone to drive them home after the exam.
There’s also the cost.
Not all insurance plans cover the full cost of a colonoscopy. Wender said if a polyp is found, Medicare will sometimes change the description of the exam from “screening” to “diagnosis.” That can require the patient to pay more.
Allison notes that people with high deductibles or high copayments can also get hit with an expensive bill.
He adds the underinsured and people without insurance, in particular, can’t afford the procedure. Even the cost of the pre-procedure liquid and other items can discourage low-income patients.
Dr. Aasma Shaukat, a member of the American Gastroenterology Association, adds there is still a lack of awareness among patients about the need for colon cancer screening. She said many people over the age of 50 don’t know the risks.
Benefits of getting a colonoscopy
Screening is vital because colorectal cancer often shows no signs or symptoms in its early stages. Many people do not develop any obvious symptoms until the cancer is growing, spreading, and harder to treat.
Colorectal cancer develops from small growths called polyps in the colon, also called the large intestine, and the rectum.
“Screening lets us catch colorectal cancer early, while it is still treatable,” said Commander Djenaba Joseph, MD, MPH, medical director of the CDC’s Colorectal Cancer Control Program. “If we catch colorectal cancer early, more than 95 percent of patients are still alive five years later. If we catch it after it has grown and spread, treatment doesn’t always work well.”
The colonoscopy is the most common screening test for colorectal cancer in the United States. Most medical experts, including Allison and Wender, agree it’s an excellent test for detecting colon cancer.
In the past, colonoscopies have been proclaimed to be more than 90 percent effective, although Allison and others point out there has never been a thorough study on the accuracy of colonoscopies. Shaukat said three such studies are under way, but results aren’t expected for seven years.
However, he still says a colonoscopy is a worthwhile test if it’s done properly.
One popular feature of the colonoscopy is, if no polyps are found, another colonoscopy is generally not recommended for another 10 years.
For individuals with risk factors such as a family history of colon cancer or certain medical conditions, such as inflammatory bowel disease, Lynch syndrome or familial adenomatous polyposis, a colonoscopy is the only recommended test and is typically recommended at a younger age.
The advantages of colonoscopy alternatives
The problem is that if someone doesn’t get screened because they don’t want to go through the expense or unpleasantness of a colonoscopy, then the exam isn’t effective at all.
Those without a family history of colorectal disease or other risk factors have a variety of alternative tests to choose from.
Several alternative tests, some of which have been around for a while, are now getting a closer look. Experts like Allison and Wender say doctors should be recommending them more to patients, especially those who don’t want or can’t afford a colonoscopy.
One option is the fecal immunochemical tests, or FIT, which are approved by the Food and Drug Administration (FDA). It’s used as the first line colorectal cancer screening test in most of the world, including Canada, Israel, the Netherlands, Italy, France, Taiwan, China, South Korea, Scotland, and soon, England. It’s recommended as the screening test of choice by the European Union Guidelines.
FIT is a stool test and can be ordered by your doctor. There are different kinds of FIT tests, both wet and dry. Allison recommends you check to be sure your test has “evidence of its performance characteristic in large average risk populations and evidence of quality control over development and interpretation.”
If your FIT test is negative, you repeat the test a year later. If the test is positive, you’re advised to schedule a colonoscopy. FIT costs about $20 or less and is covered by Medicare and most health insurance plans.
A single FIT test detects about 73 percent of colorectal cancers. But because you use FIT every year, 10 screenings over 10 years make it just as good as one colonoscopy every 10 years, Wender said.
The National Colorectal Cancer Roundtable has endorsed FIT-based testing as an effective means to screen the general population for colon cancer.
There are other stool-based exams on the market too.
One is stool DNA, or sDNA. It’s another at-home stool test ordered by a doctor. The test looks for blood and abnormal DNA in the stool that may indicate the presence of colon cancer or precancerous polyps. If the test is positive, you will need a colonoscopy to remove any cancer or polyps.
The high-sensitivity fecal occult blood tests FOBT, include the sensitive guaiac test and FIT. Each has markedly improved detection rates of colorectal cancer and advanced adenomas than the old standard guaiac FOBT. Modeling studies have shown high sensitivity FOBT to be as effective as a colonoscopy if done every year.
The American Cancer Society and other organizations also recommend several other screening tests.
One is a flexible sigmoidoscopy. In this procedure, a short, flexible tube — a sigmoidoscope — is inserted into the rectum to look for polyps and cancer in the lower part of the colon. It also requires a cleaning prep and the procedure can cause cramping.
The test is recommended every five years but is not often used in the United States because a colonoscopy requires similar preparation and checks the entire colon. The reimbursement for a sigmoidoscopy is also less than the cost to the doctor for doing the test.
The final recommended test is CT colonography, sometimes called a virtual colonoscopy. It’s an X-ray procedure to inspect the colon. It too requires the same special diet and bowel prep as a regular colonoscopy.
Virtual colonoscopy does not require sedation but can be painful because the colon must be inflated with gas to provide a better view. If polyps or other abnormalities are seen, you will need a regular optical colonoscopy to remove the growths.
In addition, CT colonography is not yet CMS approved for Medicare reimbursement. Wisconsin is the only place in the United States where you can get the test reliably covered by insurance.
With all these alternatives, medical experts say there’s no reason for people not to get screened. Shaukat said colon cancer is one of the few cancers for which there is a wide variety of screening tests.
“There are a lot of good options out there,” said Shaukat. “If it takes a stool-based test to get someone in the door to get screened, then so be it.”
There are patients who worry about the accuracy of some of the alternative tests, but Allison said no exam, including a colonoscopy, is a 100 percent guarantee there are no polyps or cancer in your colon or that you won’t develop colorectal cancer in the 10-year interval recommended between tests.
“No test is perfect,” he said.
“The only thing you should be asking yourself and your doctor is which test is right for you,” said Dr. Deborah Fisher, MHS, an associate professor of medicine at Duke University. “There is no one test that is best for everybody. When it comes to colorectal cancer, the best test is the one you actually use.”
“People say ‘I feel fine, why should I go through such an unpleasant test.’ You can talk yourself out of it.”
— Dr. Richard Wender, American Cancer Society
“When it comes to colorectal cancer, the best test is the one you actually use.”
— Dr. Deborah Fisher, Duke University
This piece was originally reported on March 20, 2015. Its current publication date reflects an update, which includes a medical review by Cynthia Taylor Chavoustie, MPAS, PA-C.