Colorectal cancer is the third-most commonly diagnosed malignancy in British Columbia and the second leading cause of cancer-related death. It is estimated that in 2013, 2900 British Columbians will be diagnosed with colorectal cancer and 1180 will die from this disease.[1] Screening for colorectal cancer is known to decrease colorectal cancer morbidity, mortality, and incidence by diagnosing the disease at an earlier stage, and identifying precancerous polyps so that they can be removed.[2,3] 

Colorectal cancer screening is recommended for asymptomatic individuals between the ages of 50 and 74 years[4] and has been shown to be cost-effective for the health care system. Despite these facts, half of British Columbians are not up to date with their screening.[5] While the exact number of colorectal cancers diagnosed through screening is not known, a study surveying BC Cancer Agency patients diagnosed with invasive colorectal cancer found that only 7% of respondents had been identified through screening.[6] To address these issues, a province-wide colorectal cancer screening program using a biennial immunochemical fecal occult blood test will be implemented this year. 

The fecal immunochemical test (FIT) has been available in British Columbia for the past 5 years, and has been covered by MSP since April 2013. FITs are based on antibodies directed against human globin. FITs are more sensitive than the traditional guaiac fecal occult blood test in the detection of colorectal cancer and adenomas, and may be more specific for colonic sources of blood loss as the globin is digested in transit. Compliance is improved, as only a single stool sample is required and there are no dietary or medication restrictions.[7]

Colorectal cancer screening within a population-based program is appropriate for individuals between the ages of 50 and 74. Individuals younger than age 50 are not eligible for screening unless they have a strong family history of colorectal cancer and require a referral for possible colonoscopy. Individuals older than 74 years of age are not eligible for programmatic colorectal cancer screening. For individuals between the ages of 75 and 85, screening can be considered on a case-by-case basis for patients in good health, taking into account that the benefit of colorectal cancer screening in clinical trials does not manifest until 7 years later.[4,8] 

Screening is not appropriate in individuals over the age of 85 years as the risk of colonoscopy-associated morbidity and the risk of death due to other causes negates any benefit of colorectal cancer screening.4,8 Regardless of age, if a patient is not medically fit to undergo colonoscopy, then a FIT is not appropriate. Whether a patient is a candidate for colonoscopy needs to be decided before the FIT is ordered. 

With few exceptions, fecal occult blood tests are not useful in investigating gastrointestinal symptoms.[9] Individuals with gastrointestinal symp­toms or iron deficiency anemia should be referred for consideration of endoscopic evaluation irrespective of whether a fecal occult blood test is positive or negative. 

To summarize, FIT is recommended for individuals aged 50 to 74. FIT is not recommended in the following situations:

•    For colorectal cancer screening in individuals under age 50.
•    For colorectal cancer screening in individuals over age 74. Individuals aged 75 to 85 should be evaluated on a case-by-case basis.
•    For colorectal cancer screening in individuals who are not medically fit to undergo colonoscopy.
•    For individuals in a colonoscopy surveillance program to follow up adenomatous polyps or colorectal cancer.
•    For individuals with gastrointestinal symptoms.

For more information on the Pro­vincial Colon Screening Program, please visit www.screeningbc.ca/colon [9].
—Jennifer J. Telford, MD
Medical Director, BC Cancer Agency Colon Screening Program

References

1.    Canadian Cancer Society/Public Health Agency of Canada. Canadian Cancer Statistics 2013. Accessed 26 July 2013. www.cancer.ca/en/cancer-information/cancer-101/canadian-cancer-statistic... [10].
2.    Mandel JS, Church TR, Bond JH, et al. The effect of fecal occult-blood screening on the incidence of colorectal cancer. N Engl J Med 2000;343:1603-1607.
3.    Mandel JS, Bond JH, Church TR, et al. Reducing mortality from colorectal cancer by screening for fecal occult blood. Minnesota Colon Cancer Control Study. N Engl J Med 1993;328:1365-1371.
4.    British Columbia Ministry of Health. BC Guidelines and Protocols Advisory Committee (GPAC). Colorectal screening for cancer prevention in asymptomatic patients. Effective date March 1, 2013. Accessed 26 July 2013. www.bcguidelines.ca/guideline_colorectal_det.html.  [11]
5.    Canadian Partnership Against Cancer (CPAC). Colorectal screening initiative. Survey: Colon Cancer Screening in Canada. February 2012. Accessed 26 July 2013. www.partnershipagainstcancer.ca/priorities/2007-2012-initiatives/screeni... [12].
6.    Smiljanic S, Gill S. Patterns of diagnosis for colorectal cancer: Screening detected vs symptomatic presentation. Dis Colon Rectum 2008;51:573-577.
7.    Van Rossum L, Van Rijn A, Laheij R, et al. Random comparison of guaiac and im­munochemical fecal occult blood test for colorectal cancer in a screening population. Gastroenterology 2008;135:82-90.
8.    US Preventive Services Task Force. Screening for colorectal cancer: US Preventive Services Task Force recommendation statement. Ann Intern Med 2008;149:627-637.
9.    Niv Y, Sperber AD. Sensitivity, specificity, and predictive value of fecal occult blood testing (Hemoccult II) for colorectal neoplasia in symptomatic patients: A pro­spective study with total colonoscopy. Am J Gastroenterol 1995;90:1974-1977.