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    Colon Cancer (Diagnosis + Treatment)

    Hematological / Oncological

    Last Updated Dec 07, 2021
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    By Kerry Walker, Jonathan Lim


    • Colorectal cancer (CRC) (comprised of colon cancer and rectal cancer) is the 3rd most common cancer diagnosis (excluding non-melanoma skin cancers) in Canada.
    • Up to 40% of those individuals may receive their diagnosis through the emergency department (ED).
    • One study found that those who were diagnosed through the ED have a nearly twofold mortality risk increase.
    • Of those with CRC, up to 55% visit the ED within 12 months, and 69% of those are admitted.
    • British Columbia offers screening for colon cancer, performed by primary care providers as per guidelines from the BC Cancer Agency.

    Diagnostic Process

    Clinical presentation:

    • If presenting with symptoms, the colon cancer is likely more advanced in staging
    • Common symptoms include hematochezia, abdominal pain, or change in bowel habits.
    • Less common symptoms include anorexia, weight loss, nausea/vomiting, malaise
    • Red flags for more advanced or metastatic disease include right upper quadrant pain, abdominal distension, early satiety, supraclavicular adenopathy, or periumbilical nodules
    • Emergent cases may present with obstruction, hemorrhage or bowel perforation

    Physical Examination:

    • General physical examination, including digital rectal exam


    • There is no diagnostic role for routine laboratory investigations although screening for anemia seems reasonable.
    • Liver function tests should not be used to detect liver metastases, due to their low sensitivity
    • If clinically suspected plain films for obstruction/perforation only if CT not available
    • A CT of the abdomen and pelvis is helpful for investigating tumor-related complications such as obstruction, perforation, or fistula formation.
    • Tumour markers such as carcinoembryogenic antigen (CEA) should not be used as a diagnostic tool for CRC due to low sensitivity and limited specificity

    Risk Factors:

    • Age (increases greatly > age 50)
    • Sex (males>females)
    • Polyps
    • Family history of colorectal cancer
    • Hereditary cancer syndrome (e.g. Lynch syndrome)
    • Obesity
    • High intake of red or processed meat
    • High alcohol consumption
    • Smoking history
    • Inflammatory bowel disease
    • Ashkenazi ethnicity

    Differential Diagnostic Considerations:

    • Due to its nonspecific symptoms, the differential considerations for colon cancer include other malignancies, as well as benign lesions such as hemorrhoids, diverticulitis, infection, or inflammatory bowel disease



    • If the patient is presenting with emergent symptoms such as perforation or obstruction acute surgical consult is warranted
    • For acute GI bleed, a colonoscopy or CT angiography is indicated.
    • In hemodynamically unstable patients, CT angiography is preferred over colonoscopy.
    • If the patient is presenting with non-emergent symptoms/signs of colorectal cancer, referral to a gastroenterologist should be made in order to organize a colonoscopy

    Quality Of Evidence?


    A colonoscopy is an appropriate diagnostic investigation for CRC in both asymptomatic and symptomatic patients. A meta-analysis of 25 studies revealed a miss rate of 5.3% in symptomatic patients and 4 studies showed a miss rate of between 2-6% in asymptomatic patients.


    Related Information

    Reference List

    1. Government of Canada. (2019, December 9). Colorectal cancer. Retrieved November 17, 2021 from https://www.canada.ca/en/public-health/services/chronic-diseases/cancer/colorectal-cancer.html 

    2. Cappell, M.S. (2008). Pathophysiology, Clinical Presentation, and Management of Colon Cancer. Gastroenterology clinics of North America, 37(1), 1-24. https://doi.org/10.1016/j.gtc.2007.12.002

    3. Baer, C., Menon, R., Bastawrous, S., & Bastawrous, A. (2017). Emergency Presentations of Colorectal Cancer. The Surgical clinics of North America, 97(3), 529–545. https://doi.org/10.1016/j.suc.2017.01.004

    4. Walls, R.M., Hockberger, R.S., & Gausche-Hill, M. (2018). Rosen’s Emergency medicine: concepts and clinical practice (9th ed.). Elsevier.

    5. BC Cancer. (n.d.). Colorectal. Retrieved November 19, 2021 from http://www.bccancer.bc.ca/health-info/types-of-cancer/digestive-system/colorectal

    6. Macrae, F.A., Parikh, A.R., & Ricciardi, R. (2021). Clinical presentation, diagnosis, and staging of colorectal cancer. UpToDate. Retrieved November 17, 2021 from https://www.uptodate.com/contents/clinical-presentation-diagnosis-and-staging-of-colorectal-cancer

    7. BC Cancer. (2012, September 5). Retrieved November 19, 2021 from (http://www.bccancer.bc.ca/health-professionals/clinical-resources/cancer-management-manual/gastrointestinal/colon#Diagnostic-and-Staging-Work-Up-colon)

    8. Bass, G., Fleming, C., Conneely, J., Martin, Z., & Mealy, K. (2009). Emergency first presentation of colorectal cancer predicts significantly poorer outcomes: a review of 356 consecutive Irish patients. Diseases of the colon and rectum52(4), 678–684.

    9. Weidner, T. K., Kidwell, J. T., Etzioni, D. A., Sangaralingham, L. R., Van Houten, H. K., Asante, D., Jeffery, M. M., Shah, N., & Wasif, N. (2018). Factors Associated with Emergency Department Utilization and Admission in Patients with Colorectal Cancer. Journal of gastrointestinal surgery : official journal of the Society for Surgery of the Alimentary Tract22(5), 913–920. https://doi.org/10.1007/s11605-018-3707-z

    10. Weithorn, D., Arientyl, V., Solsky, I., Umadat, G., Levine, R., Rapkin, B., Leider, J., & In, H. (2020). Diagnosis Setting and Colorectal Cancer Outcomes: The Impact of Cancer Diagnosis in the Emergency Department. The Journal of surgical research255, 164–171. https://doi.org/10.1016/j.jss.2020.05.005

    11. Nasseri, Y., & Langenfeld, S. J. (2017). Imaging for Colorectal Cancer. The Surgical clinics of North America97(3), 503–513. https://doi.org/10.1016/j.suc.2017.01.002

    12. Kim, B. S., Li, B. T., Engel, A., Samra, J. S., Clarke, S., Norton, I. D., & Li, A. E. (2014). Diagnosis of gastrointestinal bleeding: A practical guide for clinicians. World journal of gastrointestinal pathophysiology5(4), 467–478. https://doi.org/10.4291/wjgp.v5.i4.467


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