Faecal immunochemical testing (FIT) in symptomatic patients: what are we missing?

Area of Science:

• Gastroenterology
• Oncology
• Clinical Diagnostics

Background:

• Faecal immunochemical test (FIT) is a non-invasive method for detecting colorectal cancer (CRC).
• Recent National Institute for Health and Care Excellence (NICE) guidelines (NG12 and DG30) provide frameworks for CRC triage.
• Symptomatic patients are a key population for CRC screening and early detection.

Purpose of the Study:

• To evaluate the effectiveness of FIT as a triage test for colorectal cancer (CRC).
• To assess FIT performance within the NG12 and DG30 NICE guidelines for symptomatic patients.
• To determine the sensitivity and specificity of FIT in identifying CRC and adenomas.

Main Methods:

• A single-centre prospective study was conducted on patients referred via the 2-week wait (TWW) pathway.
• Data from 612 patients were analyzed, categorizing them by NG12 (n=519) and DG30 (n=79) criteria.
• FIT was performed on all patients, with sensitivity, specificity, and predictive values calculated for CRC and adenomas.

Main Results:

• CRC sensitivity was 84.85% for NG12 and 100% for DG30. Specificity was 81.28% for NG12 and 91.89% for DG30.
• Adenoma sensitivity was approximately 30.77% for NG12 and 25% for DG30.
• FIT demonstrated high sensitivity and specificity within the NG12 pathway, with excellent sensitivity and improved specificity in the DG30 group.

Conclusions:

• FIT is an effective triage tool for CRC within the NG12 NICE guidelines, despite a residual miss rate.
• FIT shows excellent sensitivity and improved specificity for DG30, though this pathway targets lower-risk individuals.
• For the higher-risk NG12 group, additional tests or markers may be needed to minimize missed CRC cases.