CRC screening
Why labs are rethinking guaiac FOBT
FIT vs guaiac — specificity, diet prep, and what changes for a screening lab.
Guaiac FOBT reacts to any peroxidase — red meat, some vegetables, vitamin C — which is why it carries diet restrictions and a higher false-positive load.
FIT is specific to human haemoglobin, so it needs no diet prep. Head-to-head against the guaiac Hemoccult SENSA in 300 colonoscopy-referral patients, ColonView detected 97.2% of adenomas and carcinomas against guaiac’s 58.3% (Vasilyev S et al., Anticancer Res 2015;35:2873-80). Guaiac trades that sensitivity for specificity — 96.5% vs 85.8%.
For a lab, that means fewer diet-prep queries and a cleaner screening result — and the basis for a recallable programme rather than occasional one-off tests.