Cancer Care Ontario guaiac fecal occult blood test (FOBT) laboratory standards: Evidentiary base and recommendations

Objectives — To evaluate the evidence concerning gFOBT kits and to develop gFOBT standards to be implemented by the Ontario Colorectal Cancer (CRC) Screening Program (the “Program").

Design and Methods — We evaluated 3 aspects of gFOBT kits: 1) performance factors; 2) usability factors; and 3) laboratory factors. We obtained information from the published literature, other countries that use gFOBT, the internet, and gFOBT kit manufacturers' instructions.

Results — The Program should use a single brand of gFOBT kit with sensitivity ≥ 40% and specificity ≥ 95% for the detection of CRC in repeated testing. The Program should regularly monitor gFOBT performance. Participants should not restrict their diets except for eliminating vitamin C supplements and citrus fruits and juices for 3 days prior to and during stool collection; participants should not discontinue taking aspirin (ASA) or non-steroidal anti-inflammatory drugs (NSAIDs). The Program should use one or a limited number of labs; leak-proof envelopes should be used that protect samples during mailing; the lab should delay processing fecal samples for at least 48 h following stool collection; the lab should implement staff training and quality control protocols.

Conclusions — The Program should monitor and report on its performance according to these standards, and should continually assess new evidence related to CRC screening methods.