FIT-Positive but No Colorectal Cancer: Frontline Gastroenterology | October 2026

What Did the Study Find?

This real-world study followed 1,056 symptomatic FIT-positive patients without colorectal cancer (CRC) to evaluate alternative diagnoses and their relationship with faecal haemoglobin concentrations.

• The median FIT was 51 µg Hb/g faeces, with a mean patient age of 64.2 years.
• The most frequent findings were diverticulosis (475 patients) and benign colorectal polyps (387 patients).
• Median FIT concentrations were particularly elevated in:
• IBD: 311 µg Hb/g
• Vascular disease: 284 µg Hb/g
• Radiation colitis: 180 µg Hb/g
• Normal investigations: 31 µg Hb/g
• Each 10-fold increase in FIT was independently associated with greater odds of vascular disease (OR 3.93), IBD (OR 3.38), benign upper-GI conditions (OR 2.06) and perianal disease (OR 1.89).
• Higher FIT levels were associated with a lower likelihood of normal findings (OR 0.59).
• Importantly, only 64% completed gold-standard colorectal investigations, while documented safety-netting occurred in just 52%.
• A small number of patients subsequently developed CRC after initially negative or incomplete investigations.

Why Does It Matter?

FIT is increasingly used to triage symptomatic patients for colorectal cancer, but faecal haemoglobin reflects gastrointestinal bleeding rather than cancer specifically.

A strongly positive FIT should therefore not be dismissed simply because CRC has not been identified. It may indicate significant inflammatory, vascular or other gastrointestinal pathology.

GastroAGI Takeaway

A positive FIT with no detected colorectal cancer is not necessarily a false-positive test.

Higher FIT concentrations were associated with IBD, vascular lesions and other GI conditions, suggesting that FIT has broader clinical significance beyond CRC triage.

The most actionable finding is the gap in follow-up: 36% did not complete gold-standard colorectal investigations, and 48% lacked documented safety-netting.

Clinical implication: Ensure appropriate colorectal evaluation and clear safety-netting, particularly when symptoms persist or investigations are incomplete. Further investigations should be guided by symptoms, anemia and clinical risk rather than FIT concentration alone.

Evidence limitation: This retrospective study demonstrates associations, not diagnostic thresholds or proof that FIT can reliably distinguish different non-cancer GI diseases.