Accuracy of faecal immunochemical testing in patients with symptomatic colorectal cancer

Abstract

Background: The aim of this study was to determine the diagnostic accuracy of the faecal immunochemical test (FIT) for detecting colorectal cancer in symptomatic patients. Methods: This was a prospective study of patients with bowel symptoms. Stool samples were collected during rectal examination. The HM-JACKarc assay (Kyowa Medex, Tokyo, Japan) was used to quantify faecal haemoglobin (Hb); positive results were those with at least 10 g Hb/g faeces. Two-by-two tables and receiver operating characteristic (ROC) curve analysis were used to determine diagnostic accuracy; 2 and Mann-Whitney U tests were used to compare other parameters. Results: A total of 928 patients were included (M : F ratio 1 : 1⋅5; median age 72 (i.q.r. 64-80) years). The overall prevalence of colorectal cancer was 5⋅1 per cent. The FIT had sensitivity of 85⋅1 per cent, specificity of 83⋅5 per cent, positive predictive value of 22⋅6 per cent and negative predictive value of 99⋅0 per cent. ROC analysis of FIT for diagnosing colorectal cancer gave an area under the curve value of 0⋅89 (95 per cent c.i. 0⋅84 to 0⋅94). Significant bowel pathology was detected more frequently in FIT-positive patients (35⋅1 per cent versus 7⋅1 per cent in FIT-negative patients; P < 0⋅001). There were sex differences in FIT positivity (23⋅7 per cent in men versus 17⋅4 per cent in women; P = 0⋅019); the sensitivity of FIT for colorectal cancer in women was also low. False-negative FIT results were found mainly in women referred with iron-deficiency anaemia, who were found to have caecal cancer. Conclusion: FIT effectively excluded colorectal cancer in symptomatic patients. Integration of FIT into the diagnostic pathway for colorectal cancer would direct resources appropriately to patients with a greater likelihood of having the disease.

Using the faecal immunochemical test in patients with rectal bleeding: evidence from the NICE FIT study

“…These results, which focus solely on patients with RB may be added to an increasing body of evidence that the FIT could be extended for use in symptomatic patients with higher risk symptoms, including patient cohorts with rectal bleeding. [14,19–24] Amongst this evidence, two studies looked specifically at the FIT in RB; Högberg et al reported a sensitivity of 96.2% and NPV of 99.7% for CRC [19], and Digby et al reported that patients with f ‐Hb <10 µg/g were very unlikely to have serious bowel disease (1.2%) or CRC (0.03%). [14]…”

“…These results, which focus solely on patients with RB may be added to an increasing body of evidence that the FIT could be extended for use in symptomatic patients with higher risk symptoms, including patient cohorts with rectal bleeding. [14,[19][20][21][22][23][24]…”

A Review of Colorectal Cancer in Terms of Epidemiology, Risk Factors, Development, Symptoms and Diagnosis

“…NICE guidelines recommend it for the patient with unexplained changes in bowel habits and iron deficiency anemia (patients aged 60 and over, even in the absence of iron deficiency) for use in primary care or screening for suspected CRC [ 88 ]. FIT may help effectively excluded CRC among symptomatic patients [ 100 ] and, in conjunction with clinical assessment, may safely and objectively determine individual risk of CRC for further decisions about urgent or routine management [ 101 ]. Moreover, FIT is preferable to the gFOBT in terms of the detection rate, positive predictive value and participation rate [ 102 ].…”

Faecal haemoglobin concentration thresholds for reassurance and urgent investigation for colorectal cancer based on a faecal immunochemical test in symptomatic patients in primary care

“…This strategy involves giving advice to patients that their symptoms are unlikely to be due to significant GI disease, but they should seek advice should their symptoms return, continue, or worsen. Further, it is now clear that FIT can be employed in this context for all symptomatic patients, not only lowrisk 9,10 as recommended in NICE NG12 6 and DG30, 7 but also those who report high-risk symptoms, [11][12][13][14][15] particularly rectal bleeding. 16 However, uncertainty remains around a numerical f-Hb threshold to discriminate between those who are and are not likely to benefit from investigation.…”