Introduction The diagnosis of colorectal cancer (CRC) in primary care can be challenging as symptoms are variable with poor specificity. We investigated the diagnostic accuracies of faecal immunochemical test for haemoglobin (FIT) and faecal calprotectin (FCP) in symptomatic patients referred from primary care for urgent lower gastrointestinal investigations via the two-week wait colorectal pathway.
Method 1016 patients were prospectively recruited between January 2015 and September 2016. In total 612 patients returned stool samples, completed colonic investigations and were included in the final statistical analysis (51% women, median age 68 years, IQR: 57–76). FIT was performed on HM-JACKarc analyser (Kyowa Medex), and FCP by EliA Calprotectin immunoassay (Thermo Fisher Scientific). Any detectable FIT (detection limit 7 µg Hb/g faeces) and a cut-off of 50 µg/g for FCP were considered positive.
Results 37 (6%) patients were diagnosed with CRC. The negative predictive value (NPV) of FIT vs. FIT plus FCP was the same at 99% (95% CI 98% to 100%). The sensitivity and specificity of FIT was 84% and 89%, respectively. Whereas, it was 89% and 86% for FIT combined with FCP. The ROCs for FIT, FCP and both faecal biomarkers combined showed AUC 0.90, 0.73 and 0.91, respectively. Faecal ćhaemoglobin measurements were significantly higher in left-sided colonic lesions compared ćwith the right side; 490 µg Hb/g faeces vs. 90 µg Hb/g faeces; p=0.007).
Conclusion Undetectable FIT is sufficiently sensitive to exclude colorectal cancer, with higher values in left-sided lesions. FCP in combination does not appear to provide additional diagnostic information. Further studies to determine the health economic benefits of implementing FIT in primary care are required.
Disclosure of Interest M. Widlak: None Declared, C. Thomas: None Declared, M. Thomas: None Declared, C. Tomkins Conflict with: Educational lectures on behalf of Thermo Fisher Scientific Ltd., S. Smith: None Declared, C. Darby: None Declared, N. O’Connell: None Declared, S. Wurie: None Declared, L. Burns: None Declared, C. Harmston: None Declared, C. Evans: None Declared, C. Nwokolo: None Declared, B. Singh: None Declared, R. Arasaradnam Conflict with: Educational lectures on behalf of Thermo Fisher Scientific Ltd.
- Faecal calprotectin
- Colorectal cancer
- Faecal biomarker
- Faecal immunochemical test for haemoglobin
- Two-week wait pathway