Colonoscopy

Recently, Dave turned 50.

Over the years, he has been very conscious of his health. He eats low fat, high fibre diet. He believes in the dictum, “Those who live by the sweets, die by the sweets.” He is careful about his weight. He exercises regularly – 30 minutes each day, five times a week. He gets his prostate checked.

“So, Doc, what’s missing? Is it time for colonoscopy? Is it the best test for prevention and early detection of colorectal cancer?

Dave has no risk factors and no symptoms of colon and rectal cancer. So, here are the questions:

1. Should a 50-year-old asymptomatic individual undergo screening tests for prevention and early detection of colon and rectal cancer?
2. If yes, what is the best test – is it colonoscopy?

It is unfortunate that prevention and early detection of colorectal cancer does not get the same publicity as breast and prostate cancer. Last time media paid some attention to this subject was when the former U.S. President Ronald Reagan was found to have precancerous colonic polyps. That was many years ago!

Some young prominent Canadians have had colorectal cancer. Recently, Pamela Wallin, 48, broadcaster and author was diagnosed and treated for colorectal cancer. Former leader of the Alberta Liberal Party and Leader of the Opposition in Alberta Legislature, Lawrence Decore, died from colorectal cancer at a young age. Former Premier of Prince Edward Island, Joe Ghiz, died of colorectal cancer at age 51 (1945-1996).

Answer to Dave’s first question: Yes, there is evidence to suggest that asymptomatic 50 year olds should undergo screening for colorectal cancer.

Answer to Dave’s second question is not that straight forward. The screening tests recommended by the Canadian Task Force on Preventive Health Care (discussed here on August 9th) for asymptomatic people over the age of 50, who are at normal risk, are:

1. Annual or biennial (every two years) fecal occult blood tests (to check for non-visible blood in the stool)
2. Flexible sigmoidoscopy (an office procedure) – probably every five years.

Unfortunately, one-quarter of colorectal cancers or serious precancerous lesions may be missed by these tests.

Colonoscopy is considered the gold standard. Some experts suggest colonoscopy every 10 years for asymptomatic individuals after the age of 50. In an editorial in the New England Journal of Medicine (August 23), Dr. Allan Detsky of University of Toronto says, “I recommend a single screening colonoscopy at the age of 50, with perhaps another in 10 to 15 years if no precursor lesions are found.”

But can we afford colonoscopy for all asymptomatic Canadians over the age of 50? Probably not! Then what should one do? The best thing is to discuss your concerns with your family doctor and he can assess your risks and order appropriate tests. Blood test – CEA –is not a good test for screening and is not recommended for this purpose and should not be done.

Although screening for colorectal cancer should begin routinely at the age of 50, adherence to recommendation is 50 per cent or less. This is unfortunate and there is no mechanism to ensure better compliance.

In Canada, colorectal cancer is the third most common cancer. Both sexes are equally affected. Last year, about 17,000 Canadians were diagnosed with colorectal cancer and about 6500 died from this disease. So, Dave, you should undergo screening and my recommendation would be colonoscopy.

Have I had one? Yes.

Dave is a composite character representing a typical patient.

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