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The article Colonoscopy Still ‘Gold Standard’ For Preventing Colon Cancer, Johns Hopkins Expert Says mention that the colonoscopy is the gold standard in detecting colon cancer even though there are still other tests that help.

A colon cancer expert at Johns Hopkins says that a colonoscopy remains underused by Americans but remains the test of choice for preventing the number-two cancer killer overall. [...]

“People shouldn’t be afraid. The days of discomfort, doubt and danger often associated with a colonoscopy are long gone. And, most importantly, it saves lives,” adds Kalloo.

However, another article COLONOSCOPY: IS IT WORTH THE RISK? says otherwise.

So our desire to prevent it isn't surprising, especially when we are told that regular colonoscopies after age fifty make colorectal cancer "more than 90% curable — but only if you get tested in time." [2]

Actually, this is a lie! Screening colonoscopies do not prevent or materially reduce anyone's risk of colorectal cancer regardless of age. And if anything, they may actually increase your overall risk of cancer, and not just colorectal.

Also, another article Standard Colonoscopy mentions

Even though this test is highly sensitive, it still may not detect all small polyps, nonpolypoid lesions, or cancers.

So, is colonoscopy the gold standard in detecting colon cancer?

  • I edited to include the title of each referenced article. Having the title not only makes it look better/more readable, it also make it easier to search for the article again if the hyperlink becomes broken (if the article is moved or its URL scheme is changed). – ChrisW Oct 9 '14 at 11:07
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    Warning: the term "gold standard" has a specific (if deprecated) medical meaning. It is possible to have a situation where a test was both the gold standard for diagnosis and not warranted. I am tempted to edit the question to remove the term to focus on the real claim - that mass-screening colonoscopies for people over 50 is a worthwhile treatment to save lives. – Oddthinking Oct 9 '14 at 11:24
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    @Oddthinking I edited the quotes and the title. You might like to reverse my edit, or make a corresponding edit to the text of the question. 'gold standard' only appears in the title (not text) of the first article. IMO titles are often written by a (journalistic) editor, not the (scientific) author, so as you said the substance/body of the article is more important than its title. – ChrisW Oct 9 '14 at 14:11
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    "Screening colonoscopies do not prevent or materially reduce anyone's risk of colorectal cancer regardless of age" - this sentence is nonsensical babbling. Of course a test for cancer doesn't reduce the odds of it being there. – Compro01 Oct 9 '14 at 14:28
  • "is colonoscopy the gold standard in detecting colon cancer" -- I don't think this is really the question you want to ask. Something can be the "gold standard" (see def #2)--that is considered ultimate--while realistically not being the most effective. IOW, the definition of "gold standard" (in this context) is all about perception, not about reality. – Flimzy Oct 9 '14 at 17:00
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Q 1: Does colonoscopy screening reduce the risk of death due to colon cancer?

In several studies, sigmoidoscopy (a type of colonoscopy where only the last part of the colon -- sigmoid and rectum -- were checked), was associated with lower colorectal cancer incidence and mortality

Q 2: Is colonoscopy the gold standard in detecting colon cancer?

"While colonoscopy is often referred to as the gold standard, and is suggested as preferred screening test by many guidelines, others recommend FS [flexible sigmoidoscopy] based on available higher quality evidence" (World Journal of Gastroenterology, 2018).

Evidence:

1) Screening for Colorectal Cancer: A Systematic Review and Meta-Analysis (Clinical Colorectal Cancer, 2016):

To evaluate the effectiveness of colorectal cancer (CRC) screening in asymptomatic adults...Meta-analysis across 4 RCTs [randomized clinical trials] for guaiac fecal occult blood testing (gFOBT) and flexible sigmoidoscopy (FS) screening showed a reduction of 18%... and 26% in CRC mortality for the screening group compared to controls, respectively.

2) Effect of flexible sigmoidoscopy-based screening on incidence and mortality of colorectal cancer: a systematic review and meta-analysis of randomized controlled trials (PLoS, 2012):

FS screening reduced CRC incidence by 32%...and CRC-related mortality by 50%.

3) Systematic review of colorectal cancer screening guidelines for average-risk adults: Summarizing the current global recommendations (World Journal of Gastroenterology, 2018):

Research including randomized controlled trials has shown that annual FOBT reduces CRC mortality by approximately 30%[2-8], whilst both annual and biennial FOBT screenings reduce CRC incidence[9]. However, those reductions can be obtained only if a positive FOBT is followed by more invasive investigations such as colonoscopy.

Colonoscopy is often referred to as the CRC screening gold standard because it allows an examination of the complete colon and it can remove pre-cancerous polyps immediately. However, whilst randomized controlled trials (RCTs) demonstrated that FS screening reduces CRC incidence and mortality[10,11], similar high-quality evidence is lacking for screening colonoscopy.

4) Stool tests are usually done before endoscopy (CDC.gov).

Background

Colorectal cancer usually appears after age 50. In early stages, it may be without any symptoms, such as abdominal pain, constipation, feeling of incomplete bowel emptying, blood in the stool or weight loss (Mayo Clinic).

5-year survival for localized colorectal cancer (discovered early) is 90% and for advanced cancer with metastases (discovered late) only 14% (Cancer.org).

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