Canadian Tast Force recommends against colonoscopy as screening test for colorectal cancer

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Wednesday, February 24, 2016 9:40 am Email this article

“We recommend not using colonoscopy as a primary screening test for colorectal cancer,” according to the guideline recommendations on screening for colorectal cancer in primary care by the Canadian Task Force on Preventive Health Care. Instead, they recommend testing for small amounts of blood in the stool (fecal occult blood testing).

They also recommend against screening people 75 and older for colorectal cancer because studies have found that such screening does not reduce mortality from colon cancer.

Recommendations

Other Recommendations by the Task Force

Their recommendations are as follows:

• We recommend screening adults aged 60 to 74 years for colorectal cancer with fecal occult blood testing (either guaiac fecal occult blood testing or fecal immunochemical testing) every two years or flexible sigmoidoscopy every 10 years. (Strong recommendation; moderate-quality evidence)
• We recommend screening adults aged 50 to 59 years for colorectal cancer with fecal occult blood testing (either guaiac fecal occult blood testing or fecal immunochemical testing) every two years or flexible sigmoidoscopy every 10 years. (Weak recommendation; moderate-quality evidence)
• We recommend not screening adults aged 75 years and older for colorectal cancer. (Weak recommendation; low-quality evidence)
• We recommend not using colonoscopy as a screening test for colorectal cancer. (Weak recommendation; low-quality evidence)

“These recommendations apply to adults aged 50 years and older who are not at high risk for colorectal cancer. They do not apply to those with previous colorectal cancer or polyps, inflammatory bowel disease, signs or symptoms of colorectal cancer, history of colorectal cancer in one or more first-degree relatives, or adults with hereditary syndromes predisposing to colorectal cancer (e.g., familial adenomatous polyposis, Lynch syndrome).”

Fecal occult blood screening does NOT reduce death rate over 30 years

Colon cancer screening (fecal occult blood screening) does NOT reduce death rate over 30 years

The Canadian Task Force recommends using fecal occult blood testing, however…

Screening for colon cancer (fecal occult-blood testing), either every year or every other year, did NOT reduce the total risk of death after a 30 year followup according to a recent analysis of the Minnesota Colon Cancer Control Study as noted by Prof. H. Gilbert Welch, MD in his most recent book Less Medicine, More Health: 7 Assumptions That Drive Too Much Medical Care.

The percentage of people who had died from any cause after a 30-year follow-up was exactly the same in each group (71% of people had died in each group).

• 71% of people had died in those screened for colon cancer every year for 11 years
• 71% of people had died in those screened for colon cancer every other year, a total of 6 times
• 71% of people had died in those who were NOT screened for colon cancer

The entire article of what Prof. H. Gilbert Welch, MD says about this is posted here.

Do Any Screening Tests Reduce Mortality?

Only One Screening Test Has Been Shown to Reduce Total Mortality Notes Prof. Welch

“There is only one cancer screening test that has definitively been proven to help people live longer: lung cancer screening in heavy smokers,” writes Prof. H. Gilbert Welch, MD in his most recent book Less Medicine, More Health: 7 Assumptions That Drive Too Much Medical Care.

(It is from Chapter 3 / Assumption #3: Sooner Is Always Better: Disturbing truth: Early diagnosis can needlessly turn people into patients, under the section titled “Does Screening Save Lives?”)

“Why?

“Because heavy smokers face a twenty- to thirty-fold [20- to 30-fold] increased risk of lung cancer death.

“In other words, for heavy smokers, lung cancer is a big component of their overall death rate.”

To say this another way…

• Breast cancer screening has not been shown to reduce the total risk of death over some number of years
• Prostate cancer screening has not been been shown to reduce the total risk of death over some number of years
• Colon cancer screening has not been been shown to reduce the total risk of death over some number of years
• Oral cancer screening has not been been shown to reduce the total risk of death over some number of years
• Screening for other cancers has not been been shown to reduce the total risk of death over some number of years

He started the chapter by saying, “THIS CHAPTER MAY CHALLENGE your assumptions about screening—specifically, cancer screening.”

The entire article is posted here.

Other Articles About Medical Screening and Their Lack of Efficacy

Other articles about screening tests and their lack of efficacy at reducing total mortality are posted here

Other articles about medical screening tests are posted here.

Reference

Care CTFoPH. Guidelines: Recommendations on screening for colorectal cancer in primary care. CMAJ, 2016 Feb 22; http://www.cmaj.ca/content/early/2016/02/22/cmaj.151125

Articles on the same subject can be found here:

• Cancer screening (Does it do any good?)

• Cancer, Colorectal