Colon cancer is amongst the most prevalent types of cancer in the world. Colon cancer is also referred to using the term colorectal cancer. Colorectal cancer refers to any cancerous infection that originates either from the rectum or the colon. The term colorectal cancer will subsequently be used in the rest of the paper. High incidence, prevalence and mortality rates of this type of cancer have triggered a lot of research into the subject. A notable research finding from the different studies is that early and regular screening can act as a secondary prevention measure for colorectal cancer. The various screening strategies that have been recommended are majorly classified into the stool-based tests and direct visualization tests. Although the type of screening strategy depends on an individual’s decision, in this paper, the colonoscopy test is recommended as a preventive screening strategy. Besides the use of colonoscopy as a screening strategy, the current paper delves into the epidemiology of colorectal cancer.
Epidemiology
Amongst the different types of cancers, colorectal cancer is ranked as the second leading cause of cancer deaths in the United States (Siegel et al., 2020). An estimated 147,950 individuals are likely to be diagnosed with colorectal cancer in 2020 (Siegel et al., 2020). An estimated 53,200 colorectal cancer deaths are likely to be reported (Siegel et al., 2020). For every 100000 persons, the incidence rates for colorectal cancer between 2012 to 2016 were 30, 45.7 and 89 for Asian, Blacks and Alaska Natives, respectively (Siegel et al. 2020). In the US 1 in every 23 men (4.4%) and 1 in every 25 women (4.1%) are likely to develop colorectal cancer during their lifetime (American Cancer Society (ACS), 2020b).
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Risk Factors and Risk Assessment
Various risk factors are associated with colorectal cancer. The American Cancer Society(ACS, 2020a) has documented the risk factors to include the controllable risk factors and those that are uncontrollable. The controllable risk factors are the factors that risk factors that human beings can change such as physical inactivity, being overweight or obese, particular diets, smoking, and excessive alcohol use (ACS, 2020a; Sur et al., 2019). Some of the diets that increase the risk of colorectal cancer include lots of processed meats and meals that are rich in red meats, e.g. beef, lamb or pork.
The non-controllable risk factors of colorectal cancer are the factors which human beings cannot change. These factors include advanced age, a family history of colorectal cancer, a history of colorectal cancer or colorectal polyps, a history of inflammatory bowel disease (IBD), inherited syndromes such as lynch and familial adenomatous polyposis, having type two diabetes and racial predisposition (ACS, 2020a: Sur et al., 2019). African Americans and Alaska Natives have a higher predisposition of colorectal cancer. Individuals with a family history of colorectal cancer are advised to start screening at a young age and have more frequent screenings carried out using colonoscopy (USPSTF, 2016). Age is a notable factor amongst the other risk factors. Some young individuals are diagnosed with colorectal cancer; however, the risk of developing colorectal cancer increases as age advances. The risk of having colorectal cancer is particularly high after hitting 50 years (USPSTF, 2016). This factor informs the need for increased and regular screening for individuals older than 50 years.
Patient Population
Early colorectal cancer screening is essential not only as a diagnostic tool but also as a secondary preventive measure. Cancer treatment and intervention measures are more successful when the cancer is diagnosed at an early stage (Sur et al., 2019). The mortality rates of colorectal cancer have been shown to decrease with early and regular screening (Sur et al., 2019). The United States Preventive Services Task Force (USPSTF) recommends that colorectal cancer screening should be started at age 50 years and should be continued regularly depending on the screening strategy until individuals turn 75 years (USPSTF, 2016). The increased risk of developing colorectal cancer after the age of 50 years informs the recommendation to start the screening at 50 years. The diagnosis of colorectal cancer is most common amongst individuals aged 65 to 74 years (USPSTF, 2016). The median age for individuals diagnosed with colorectal cancer has been found as 68 years (USPSTF, 2016). The decision to discontinue screening after 75 years is guided by the finding that a proportion of individuals aged more than 75 years will not be healthy enough to go through treatment even if colorectal cancer is diagnosed. However, the decision to screen when aged between 76 to 85 years is an individual one and should be guided by considerations such as the general health of an individual, and past screening history (USPSTF, 2016). Screening is, however, likely to be beneficial for individuals older than 75 years who have never been screened.
Colonoscopy Test
Colonoscopy is amongst the screening strategies that have been recommended by the USPSTF. The colonoscopy test is a direct visualization test that involves the insertion of a flexible tube (colonoscope) into the rectum and the large intestines. A camera attached at the tip of the tube enables a doctor to view any abnormalities in the colon and rectum. The visualization of abnormalities helps detect any cancerous growths. The colonoscopy testing interval has been recommended to be once in every ten years (USPSTF, 2016). The long screening interval has been cited as one of the strengths of this test since the frequency of screening required is lesser than in other screening strategies. Another of the advantages of colonoscopy is that if a positive result is obtained, diagnosis follow-up can be conducted in the same test. The colonoscopy test also serves as a follow-up test to other screening tests such as the stool-based tests. A colonoscopy test is recommended as a confirmatory test in scenarios where other tests give positive findings. Colonoscopy test has high specificity and sensitivity (Sur et al., 2019). The colonoscopy test acts as a standard to these other tests.
The colonoscopy test also has its weaknesses. One of the weaknesses of the colonoscopy test is that it is quite invasive and tends to cause anxiety and discomfort to individuals (USPSTF, 2016). Another of the shortcomings of the colonoscopy test is that it is associated with infections, colonic perforations and bleeding. The other weakness of the colonoscopy test is linked to some of the measures that have to be observed before conducting the examination. Bowel preparation entails the bowel system being almost clear, which may subsequently cause dehydration and electronic imbalances. The use of sedatives during the procedure may also cause cardiopulmonary issues.
The USPSTF recommends colorectal cancer screening for average-risk and asymptomatic individuals aged over 50 years but no more than 75 years. The average risk individuals exclude individuals with a personal or family history of colorectal cancer, IBD genetic disorders linked to colorectal cancer. Despite some of the notable harms associated with colonoscopy screening strategy, the test has overall net benefits of decreasing morbidity and mortality. An average of 270 life-years is gained for every 1000 individuals screened using colonoscopy (USPSTF, 2016). An average of 24 deaths for every 1000 individuals screened are avoided when using the colonoscopy test (USPSTF, 2016). Some studies have suggested reducing the starting age of colonoscopy screening to 45 years while increasing the screening interval to 15 years. Such a change resulted in a similar number of life-years gained as in the 10-year interval starting at 50 years while in another study, there was a decrease in life-years gained (USPSTF, 2016). In overall, the colonoscopy screening strategy is a useful technique which can be used as a secondary preventive measure of colorectal cancer.
References
American Cancer Society (ACS). (2020a). Colorectal Cancer Risk Factors . Cancer.org. Retrieved 10 August 2020, from https://www.cancer.org/cancer/colon-rectal-cancer/causes-risks-prevention/risk-factors.html .
American Cancer Society (ACS). (2020b). Key Statistics for Colorectal Cancer . Cancer.org. Retrieved 10 August 2020, from https://www.cancer.org/cancer/colon-rectal-cancer/about/key-statistics.html .
Siegel, R., Miller, K., Goding Sauer, A., Fedewa, S., Butterly, L., & Anderson, J. et al. (2020). Colorectal cancer statistics, 2020. CA: A Cancer Journal For Clinicians , 70 (3), 145-164. https://doi.org/10.3322/caac.21601
Sur, D., Colceriu, M., Sur, G., Floca, E., Dascal, L., & Irimie, A. (2019). Colorectal cancer: evolution of screening strategies. Medicine And Pharmacy Reports , 92 (1), 21-24. https://doi.org/10.15386/cjmed-1104
The United States Preventive Services Task Force (USPSTF). (2016). Recommendation: Colorectal Cancer: Screening | United States Preventive Services Taskforce . Uspreventiveservicestaskforce.org. Retrieved 10 August 2020, from https://www.uspreventiveservicestaskforce.org/uspstf/recommendation/colorectal-cancer-screening .
