Fecal occult blood testing (FOBT) and fecal immunochemical testing (FIT) are validated screening tools for asymptomatic populations at average risk of colorectal cancer (CRC). Carcinoembryonic antigen (CEA) is a serum marker that has established roles in prognosis, surveillance and monitoring of treatment response in patients with diagnosed colorectal cancer. They are not designed, validated, or sufficiently accurate for diagnostic evaluation in symptomatic patients or those with abnormal clinical findings.
Using these tests in a diagnostic context (e.g., rectal bleeding, iron-deficiency anemia, change in bowel habits, palpable mass, or abnormal imaging) can lead to false reassurance, delayed colonoscopy, and delayed cancer diagnosis.
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