Fecal occult blood testing for colorectal cancer screening

I was pleased to see the topic of colorectal cancer (CRC) screening addressed in the September 2005 issue of Canadian Family Physician.¹ The burden of CRC in Ontario is indeed substantial; CRC is the fourth most common cancer and the second (first among non-smokers) leading cause of death from cancer in Ontario. Screening for CRC in Ontario is a priority and long overdue as a subject of inquiry and focus of effort.

The article by Cotterill, Gasparelli, and Kirby¹ reporting on the feasibility of endoscopy performed by non-specialists (eg, general practitioners, family physicians) is timely and interesting. The authors report results from their 2-year practice-based program of screening colonoscopy performed in a local hospital by trained family practitioners. The authors found the procedure to be safe and administratively feasible.

While the initiative that the authors have undertaken and their commitment to the health of their community are tremendous, current evidence supports population-based screening programs that use fecal occult blood testing (FOBT) as the primary screening modality, with colonoscopy largely reserved for investigation of abnormal FOBT results. The authors cite several studies that demonstrate a reduction in CRC mortality attributable to screening; interestingly, several of these key studies have used FOBT as the primary screening modality.^2,3 From a population-health standpoint, CRC screening using FOBT is preferable to resource-intensive and invasive procedures such as colonoscopy. Many other countries (eg, England, Australia, Finland, Italy, Israel) have instituted successful programs using this inexpensive, accessible, and effective screening maneuver.

Regarding screening colonoscopy, the small but important risks of iatrogenic bowel perforation, hemorrhage, and death, although the most serious outcomes, are not the only concerns patients have. Other factors determine its acceptability and overall success, such as the discomfort of the prerequisite complete bowel preparation and the inconvenience of the procedure, which often requires 2 days of preparation and recovery. Fecal occult blood testing circumvents these objections.

The Canadian National Committee on Colorectal Cancer Screening recommends multiphasic screening, beginning with annual or biennial FOBT for 50- to 74-year-olds, and follow up as necessary by colonoscopy, barium enema, or flexible sigmoidoscopy (based on patient preference and availability).⁴ The Canadian Task Force on Preventive Health Care gives FOBT a grade A recommendation.⁵

The authors perhaps misinterpret the recommendations of the Ontario Expert Panel on Colorectal Cancer⁶ to incorrectly state that the program should “expand to use colonoscopy as the primary screening method when resources are available.”¹ In fact, the panel recommended that the “program should be expanded to include the option of direct visualization of the colon (ie, colonoscopy or double-contrast barium enema … only [to] be contemplated when the program is assured that there is sufficient colonoscopy and double-contrast barium enema capacity [italics added]).”⁶ The panel based their recommendations on their assessment of each screening test’s evidence of efficacy and effectiveness, acceptability, and system capacity. The panel recommended that screening programs focus attention on “evaluative studies” that aid in making decisions about ideal “screening frequency, compliance, provider acceptance, and cost” associated with these modalities.⁶ These goals have not yet been completely accomplished.

Moreover, the panel advised that Cancer Care Ontario “establish a representative multi-stakeholder advisory structure to provide ongoing direction regarding the design and operation of the CRC screening program.”⁶ Cancer Care Ontario has done this and continues to work with the Ontario Ministry of Health and Long-Term Care and stakeholders to create a provincial population-based screening program that is feasible and of high quality.