SOURCE: Ontario Association of Gastroenterology (OAG)

Ontario Association of Gastroenterology (OAG)

February 29, 2016 15:30 ET

OAG's Response to Task Force Recommendations on Colon Cancer Screening

TORONTO, ON --(Marketwired - February 29, 2016) - The Ontario Association of Gastroenterology (OAG) believes that "Colonoscopy is probably the best colon cancer screening test, it's just not proven yet," according to OAG President Dr. Iain Murray. "The OAG is concerned that a recent report is being understood as saying 'don't do colonoscopies', and that's an incorrect understanding," Murray states. He adds that colonoscopies promote prevention of cancer, thus supporting the current emphasis in health care on overall wellness, and not just treatment.

Murray is responding to the Canadian Task Force on Preventive Health Care's recently released recommendations for colon cancer screening. The Task Force recommends fecal occult blood tests (FOBTs) or flexible sigmoidoscopy for first-line screening instead. "The Task Force states there is not enough evidence that colonoscopy should be used as a primary screening test. This doesn't mean they think colonoscopy will not save lives; it only means that, to date, there is no high quality evidence in the medical literature that shows it will," says Murray. Recent media reports have interpreted this to mean colonoscopy should never be done; this is a false interpretation, says Dr. Michael Gould, Chair of the OAG's Out of Hospital Endoscopy Committee: "Colonoscopy likely will save more lives than the other types of tests available; we just don't have conclusive evidence yet, so the Task Force was not able, at this time, to recommend it be done." 

Colonoscopy is considered the gold standard. Indeed, if anything is found on FOBT or sigmoidoscopy, patients are referred for colonoscopy. "There is no doubt that colonoscopy is a superior test," Murray says. "The problem lies in the fact that it has not been subjected to large randomized control trials that prove colonoscopy saves lives. These trials have not been done because, in the United States, it is considered unethical to randomize people to NOT receive a colonoscopy. There are some trials underway in Europe, but it will be many years before these results are available," he states. There is evidence from retrospective trials that colonoscopy prevents colon cancer and saves lives, however these trials are not considered strong enough to be reviewed by the Task Force. 

FOBTs and flexible sigmoidoscopies are used to detect existing cancers. If caught early enough, before symptoms occur, cancer can be removed before it gets a chance to spread. Unfortunately, FOBTs only find a quarter of cancers that are present, and even then those that are more advanced. Flexible sigmoidoscopy shows only half the bowel and only detects half of cancers. "This is like doing a mammography on only one breast, and consistently ignoring the other," Murray says. "You only have half the information you need to determine whether you are healthy." Gould adds "If sigmoidoscopy has been shown to be effective, colonoscopy goes at least as far but sees more and is therapeutic. This is one of the clear take-aways from the Cancer Care Ontario evidence-based document published in November 2015." He is referencing "Colorectal Cancer Screening in Average Risk Populations: Evidence Summary", a quality initiative of the Program in Evidence-Based Care, which studied the benefits and harms of screening for individuals with an average risk of colorectal cancer, the optimal primary screening test(s) for this population, and other relevant factors.

"As gastroenterologists, we would rather prevent cancer by finding polyps," says Gould. Polyps are growths on the lining of the bowel that can eventually deteriorate into cancer. Polyps are found up to 40% of the time and precancerous adenomatous polyps up to 35% of the time. Studies have shown that more than 50% of those high risk polyps are out of the reach of the sigmoidoscope and are unlikely to be picked up by stool testing. Only colonoscopy will detect and remove polyps so that cancer does not develop in the first place. "FOBTs and sigmoidoscopies find some colon cancers, but certainly miss others, especially early ones. By finding and removing polyps, colonoscopy PREVENTS cancer from developing in the first place," Murray says.

Gould and Murray caution that a current lack of evidence does not mean that colonoscopy as a procedure should be maligned. "The therapeutic benefits of colonoscopy more than compensate for its costs. Compare the short-term cost of this therapeutic procedure against the long-term cost of cancer treatment, and it's easy to see that the Task Force recommendation provides a budgetary 'quick fix' while ignoring the future ramifications for both our physical and fiscal health," states Gould.

Both Drs. Murray and Gould recommend that each patient should discuss these issues with their family doctors. "The most important thing is to get involved in colon cancer screening between the ages of 50 and 75," according to Gould. The OAG recommends that this should be done before 50 if there is a family history, or at any time if there are symptoms such as bleeding, change in bowel habits, abdominal pain or weight loss. "Doing any test is better than nothing at all," says Murray; "Time will tell if the best test is colonoscopy. Meanwhile, until better evidence is available, we will follow the appropriate guidelines."

The Ontario Association of Gastroenterology (OAG) is a non-profit organization that serves the practice of gastroenterology in Ontario, promoting, maintaining and improving its knowledge and standards. The Association represents Ontario gastroenterologists in discussions, meetings and communications with other groups including the Ontario Medical Association, the Government of Ontario and other health professionals. It is the official voice of Ontario Gastroenterologists.

Contact Information

  • For further information, contact:

    Ms. Melonie Hart
    Director of Operations
    Ontario Association of Gastroenterology
    Tel: 416-494-7233 Extension 146
    Email: info@gastro.on.ca