Fecal immunochemical testing should be performed every 1–2 years, ideally as part of a colorectal cancer screening program1,2
Fecal immunochemical testing, a stool immunochemical test for occult blood, is the recommended primary colorectal cancer screening modality in Canada for average-risk individuals, defined as those aged 50–75 years without a personal or first-degree family history of colorectal cancer or advanced polyps before age 60. Fecal immunochemical testing is recommended over other modalities owing to established benefit and cost-effectiveness.1
Fecal immunochemical testing has higher positive predictive value for colorectal cancer and advanced polyps than guaiac-based fecal occult blood testing
Depending on cut-offs used, up to 54% of patients with a positive fecal immunochemical test will have 1 or more advanced polyp(s), and up to 8% will have colorectal cancer.2 The sensitivity of a single fecal immunochemical test is up to 79% (95% confidence interval [CI] 69%–86%)3 for colorectal cancer and 40% (95% CI 33%–47%) for advanced polyps.4
A single positive fecal immunochemical test should prompt referral for colonoscopy, which should ideally be performed within 8 weeks
In a given testing cycle, a single fecal immunochemical test (positive or negative) is adequate. Multiple samples are wasteful, and can potentially delay referral while the patient performs unnecessary additional tests.3
Fecal occult blood testing or fecal immunochemical testing are not intended for use in symptomatic patients, including those with suspected gastrointestinal bleeding5
A negative fecal immunochemical test should not be reassuring in symptomatic patients, who should be referred to specialists for consideration of endoscopy and other investigations.
After colonoscopy, endoscopists should provide recommendations for when to resume screening, by either fecal immunochemical testing or repeat colonoscopy; fecal immunochemical testing should not be performed before these recommended times
Early rescreening with fecal immunochemical testing after colonoscopy is discouraged, because of low yield and unjustifiable cost. However, if for any reason a fecal immunochemical test has been repeated on a patient between intervals and is positive, a referral for colonoscopy should be made.2
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Footnotes
Competing interests: None declared.
This article has been peer reviewed.
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- Fecal immunochemical testing should be performed every 1–2 years, ideally as part of a colorectal cancer screening program1,2
- Fecal immunochemical testing has higher positive predictive value for colorectal cancer and advanced polyps than guaiac-based fecal occult blood testing
- A single positive fecal immunochemical test should prompt referral for colonoscopy, which should ideally be performed within 8 weeks
- Fecal occult blood testing or fecal immunochemical testing are not intended for use in symptomatic patients, including those with suspected gastrointestinal bleeding5
- After colonoscopy, endoscopists should provide recommendations for when to resume screening, by either fecal immunochemical testing or repeat colonoscopy; fecal immunochemical testing should not be performed before these recommended times
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