Heather Bedard, C.H.E.
Colonoscopy has not been shown to decrease mortality and actually comes with an increased risk of dying from side effects. As of 2016, no studies showed a reduction in all-cause mortality with colonoscopy.[1] A decision analysis of the U.S. Preventative Services Task Force looked at the risk to benefit ratio of colonoscopy after the age of 75 and found that it produced no benefit.[2] In a study on the effect of colorectal cancer incidence and mortality the authors found that the absolute risk reduction for people aged 50-74 was 0.6% - not statistically significant.[3]
Compounded on this, is the rate of harm due to colonoscopy, which is 3.1 per 1000 procedures for a screening that lowers your risk of cancer by 0.6%. Due to the fact that colonoscopy is recommended starting at age 50, It would seem that, compared to the risk, colonoscopy is not beneficial for anyone, and particularly not asymptomatic individuals.
Another important point mentioned in a systematic review on screening for colorectal cancer, is that colonoscopy also utilizes radiation at 10mSv which is over 3 times the amount of background radiation a person would receive over a year.[4] This translates to 1 in every 1,000 people being diagnosed with cancer due to the radiation exposure. Even with this virtual scanning technology, the scans are only helpful in locating polyps over 10mm and are not sensitive for finding smaller ones. This is often dependent on the equipment used and the technician. Additionally, colonoscopy is generally only helpful with detecting cancers on the left side of the colon and not the right as show in a case control study on the association of colonoscopy and death from colorectal cancer.[5]
The use of colonoscopy has not been supported by randomized controlled trials and with the benefits uncertain, it would seem more profitable to opt out of this procedure.[6] I would not recommend this screening.
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[1] Lin JS, Piper MA, Perdue LA, et al. Screening for Colorectal Cancer: Updated Evidence Report and Systematic Review for the US Preventive Services Task Force. JAMA. 2016;315(23):2576–2594. doi:10.1001/jama.2016.3332
[2] Ann G. Zauber, Iris Lansdorp-Vogelaar, Amy B. Knudsen, et al. Evaluating Test Strategies for Colorectal Cancer Screening: A Decision Analysis for the U.S. Preventive Services Task Force. Ann Intern Med.2008;149:659-669. [Epub ahead of print 10 March 2020]. doi:10.7326/0003-4819-149-9-200811040-00244
[3] Jacob BJ, Moineddin R, Sutradhar R, Baxter NN, Urbach DR. Effect of colonoscopy on colorectal cancer incidence and mortality: an instrumental variable analysis. Gastrointest Endosc. 2012;76(2):355-64.e1. doi:10.1016/j.gie.2012.03.247
[4] Whitlock EP, Lin J, Liles E, et al. Screening for Colorectal Cancer: An Updated Systematic Review. Agency for Healthcare Research and Quality (US), Rockville (MD); 2008. PMID: 20722162
[5] Baxter NN, Goldwasser MA, Paszat LF, Saskin R, Urbach DR, Rabeneck L. Association of colonoscopy and death from colorectal cancer. Ann Intern Med. 2009;150(1):1-8. doi:10.7326/0003-4819-150-1-200901060-00306
[6] Hewett DG, Rex DK. The big picture: does colonoscopy work?. Gastrointest Endosc Clin N Am. 2015;25(2):403-413. doi:10.1016/j.giec.2014.12.002