Primary Screening Programs for Colorectal Cancer in Canada Using Non-invasive Home Tests

The fecal immunochemical (blood) test (FIT) is intended to reduce unnecessary diagnostic follow-up compared with a conventional guaiac-based fecal occult blood test (gFOBT).

In Canada, two different types of fecal occult blood tests (FOBTs) are used for non-invasive colorectal cancer (CRC) screening: the traditional gFOBT and the newer FIT. These tests detect hidden (occult) blood in stool, which may be an indicator of CRC, bleeding polyps (a precursor to CRC), or other gastrointestinal diseases. FIT is intended to offer numerous improvements that are leading to its wider acceptance by CRC screening programs. The FITs currently available in Canada include Hemoccult ® ICT and OC-Auto Micro 80 FOB Test System®.

There are a number of commercially available gFOBTs available in Canada. These include: Dencoccult III, Tri-Slide, ColoScreen, ColoScreen ES, Colocare, FOB Test Slide, Hema-Screen, One-Step FOBT, Hemoccult Sensa, Hemoccult, Rapid Response One-Step, Innovaon FOB One-Step, and Tremblay Harrison Minute Lab FOBT .

How it works

FIT differs from gFOBT in that it does not require patients to smear stool samples onto test cards with a spatula. Rather, toilet water samples are collected by dipping a brush in the water surrounding stool.

FIT also uses antibodies specific to human blood. This is intended to increase its sensitivity and specificity and eliminate dietary and drug restrictions. A table of comparisons is presented below.

Characteristics of FOBTs

Who might benefit

FOBTs are intended as screening interventions for average risk candidates. Average risk candidates include those between the age of 50 and 74, with no family or personal history of CRC. There are approximately seven million people in this age range in Canada who would be potentially eligible for primary screening for CRC. Of these, approximately five million are expected to adhere to the first level of screening.⁴

Evidence

While there are numerous claims that FIT offers better performance than the gFOBT, there are few randomized comparisons to support this assertion.^3,5 The sustained popularity of the gFOBT may be attributed to the fact that there is strong evidence that it reduces CRC mortality when followed with appropriate diagnostic treatment.^5-7 A recent systematic review concluded that no definitive statement regarding the choice between gFOBT and FIT for use in CRC screening programs could be derived. It was noted that in order to properly assess the performance of FOBTs, there is a need for research trialing FOBTs in a Canadian population.⁵

Cost

The cost of a three-day gFOBT is between $3 and $5 and a two-day FIT is between $9 and $12. The cost of manually processing these kits is approximately $7. Some FITs can be processed using automated analyzers that cost between $30,000 and $45,000. This allows for the processing of a larger volume of tests.

Screening programs across Canada

In the spring of 2009, Alberta will be launching Canada’s first complete CRC program using FIT; all other CRC programs are still in the pilot stage of development. Manitoba and Ontario established pilot CRC screening programs in 2007 using gFOBT. In 2008, the Northwest Territories set up a program using FIT. The provinces of Nova Scotia, Prince Edward Island, Newfoundland and Labrador, and British Columbia have screening programs in development, with each of them considering FIT. In other jurisdictions, CRC screening is done on an ad hoc basis, with provincial governments planning to develop screening programs using either FIT or gFOBT.

National Canadian guidelines and recommendations

Canadian Cancer Society recommendations 2006: http://www.cancer.ca/ccs/internet/standard/0,3182,3172_6291814__langId-en,00.html
National Committee on Colorectal Cancer Screening 2002:
http://www.phac-aspc.gc.ca/publicat/ncccs-cndcc/pdf/ccstechrep_e.pdf
Canadian Task Force on Preventative Health Care 2001:
http://www.cmaj.ca/cgi/reprint/165/2/206.pdf

References

1. Hemoccult II product instructions. Fullerton (CA): Beckman Coulter; 2008. Available: http://www.beckmancoulter.com/literature/ClinDiag/Hemoccult%20II%20SENSA%20elite.pdf
2. Greenwald B. Medsurg Nurs 2006;15(2):89-94.
3. Levi Z, et al. Ann Intern Med 2007;146(4):244-55.
4. Ho C, et al. Computed tomographic colonography for colorectal cancer detection in average-risk screening population: Clinical efficacy and economic evaluation. Ottawa: Canadian Agency for Drugs and Technologies in Health; 2008 [in press].
5. Harrison M, et al. Assessment of fecal occult blood tests for colorectal screening - a systematic review. Toronto: Canadian Partnership Against Cancer; 2008.
6. Schabas RE. CMAJ 2003;168(2):178-9. Available: http://www.cmaj.ca/cgi/content/full/168/2/178.
7. Allison J, et al. J Natl Cancer Inst 2007;99(19):1462-70.