The Dose20:51How often should I be having colonoscopies?
For some, a colonoscopy might be scary; others just put it off as a time commitment that can wait. But physicians and advocates agree that it’s important that people not be afraid of the screening procedure and get it done.
“Whatever you think you’re going through for a colonoscopy is no comparison to going through multiple surgeries, chemo, all sorts of treatment and potentially dying from it and the stress not just on you [but] on your family,” said Barry Stein, president and CEO of Colorectal Cancer Canada.
Stein also survived colorectal cancer.
“I would say that’s the biggest incentive to do it.”
Colonoscopies are part of the screening process for colorectal cancer in Canada. Screening in most provinces and territories often starts with an at-home stool test for the average-risk person before a colonoscopy is done, when needed.
With colon cancer being the second most common cause of cancer death in Canada, doctors say it’s an important procedure to have when necessary to catch cancer early.
Treatable when detected early
A recently published study and subsequent headlines have sparked discussions about the effectiveness of colonoscopies in detecting colorectal cancer.
A randomized controlled trial’s results published in the peer-reviewed New England Journal of Medicine found that among those invited to do a colonoscopy, there was an 18 per cent reduction in later colorectal cancers and no significant reduction in deaths.
But many of those invited never followed through.
When only people who actually had the colonoscopy were analyzed, the study’s authors found the procedure reduced the number of colorectal cancers by 31 per cent and associated deaths by 50 per cent.
Some American experts stress the trial’s results should not be misinterpreted as evidence that a colonoscopy is a bad screening test. Like any test or procedure, there are limitations.
But research shows that when colorectal cancer is detected early, it is 90 per cent treatable, according to the Canadian Cancer Society.
Recently released cancer prevalence data from the society shows that colon cancer is the fourth most diagnosed cancer in the country, but that it can be more survivable than other cancers like lung cancer when caught early.
“Colorectal screening has been a revolution, as well as fecal occult blood testing, to help diagnose colorectal cancer in an earlier stage,” said Dr. Christian Finley, a thoracic surgeon and professor at Hamilton’s McMaster University and a member of the Canadian Cancer Society’s cancer statistics advisory committee.
“Over a long period of time, this appears to have borne fruit and we’re seeing a change in the numbers and stage of cancers that we’re seeing.”
But if you or someone you know is still hesitant to get their colon examined, here’s what experts say you should know about colonoscopies.
Who should get screened
If you’re 50 to 74 years old and at average risk of getting colorectal cancer, you should be getting screened every two years, according to the Canadian Cancer Society.
In most provinces and territories, screening for colon cancer starts with an at-home poop test — commonly a fecal immunochemical test (FIT).
As part of the non-invasive FIT, a patient is required to collect a sample of their stool and ship it to a lab for analysis.
The FIT looks for blood in the stool, a common sign of colorectal cancer. Other signs include anemia (low blood count caused by low iron), unexplained weight loss, new diarrhea, new constipation and abdominal pain, gastroenterologist Dr. Jill Tinmouth told CBC’s The Dose guest host Dr. Peter Lin.
If the FIT comes back abnormal, then colonoscopy is often the next step, said Tinmouth, who is also the lead scientist at the colorectal cancer screening program at Ontario Health.
If the FIT results are normal, then screening through the at-home test can be done every two years, she added.
People who are at high risk for colon cancer may need to be tested at a younger age or more frequently, according to the society.
If you’re 75 and older, the Canadian Cancer Society recommends people speak with their primary care provider on whether they should continue getting stool tests.
Prep for the test
The colon must be clean for a colonoscopy. This prep, as it’s known, is a “major inconvenience,” according to Harvard Medical School, that takes longer than the actual procedure — but is necessary for the colonoscopy to work.
Prep includes drinking a solution that will cause “bowel-clearing diarrhea.”
Patients will also need to eat a liquid diet at least a day before the colonoscopy.
“Having a clean colon is really important because … it’s a bit of a twisty, turny space and so getting all the stool out maximizes our ability to pick up polyps and to find cancers,” said Tinmouth.
A colonoscopy is a quick day procedure often done by a gastroenterologist.
“The way colonoscopy works is it’s a long, skinny tube that’s flexible. It’s got a light and a camera on the end and we’re able to sort of look directly at the lining of the colon. And so you take a prep, you clean everything out and we get a very nice look using that instrument,” said Tinmouth.
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A colonoscopy can also find polyps — which can sometimes be cancerous — that are removed during the procedure.
Often the patient is mild or moderately sedated for the colonoscopy so that they’re not uncomfortable, says Tinmouth.
If sedated for the procedure, the patient may not be able to drive for a period of time afterward.
Finley acknowledged it can be hard — especially for those with lower socio-economic status, who work marginal jobs, or have to get childcare — to find time to get the procedure done.
“They don’t have the luxury of taking time off work to get those tests,” he said, adding the Canadian Cancer Society’s recent study on cancer prevalence shows that for colorectal and lung cancer, lower-income patients are much more likely to be newly diagnosed but are less likely to survive compared to wealthier patients.
“One of the big things we see in this study is it’s not a level playing field for people.”
How effective is a colonoscopy?
There is significant research showing that screening reduces the number of colorectal cancer diagnoses and deaths by finding precancerous polyps and early-stage tumours before symptoms begin.
Tinmouth emphasizes that colonoscopies are just one way to screen for colorectal cancer.
She adds that the recently published study on colonoscopies’ effectiveness “gives you an idea of how it’s a good test, but it’s not a perfect test.”
Other doctors have also noted that only 42 per cent of the 28,220 people invited to get the colonoscopy done as part of the study actually had the procedure done.
What if I’m uncomfortable or afraid of the procedure?
Stein and Tinmouth agree that people shouldn’t be afraid of colonoscopies.
“I think people get embarrassed and shy about the bowels, poop and all of that kind of stuff,” said Tinmouth.
“But really these are, as my mom would say, normal bodily functions. Everybody has them and does them.”
Stein was diagnosed with colorectal cancer that spread to his liver and lungs in 1995 and was told he had a 15 per cent of surviving the next five years of his life.
Now living with no evidence of the disease, he encourages people to keep up on their routine screening.
“From a practical point of view, [it’s] what we know will save lives and reduce the risk of going through what I went through — thirteen surgeries, all sorts of cancer treatments and being told that I was going to die and have a five-year survival and so forth,” he said.
“To avoid all that pain, suffering, the stress on your family, doing a simple screening test is nothing.”