Colonoscopy-controlled Intra-individual Comparisons to Screen Relevant Neoplasia: Faecal Immunochemical Test vs. Guaiac-based Faecal Occult Blood Test

F. A. Oort; J. S. Terhaar Sive Droste; R. W. M. Van Der Hulst; H. A. Van Heukelem; R. J. L. F. Loffeld; I. C. E. Wesdorp; R. L. J. Van Wanrooij; L. De Baaij; E. R. Mutsaers; S. Van Der Reijt; V. M. H. Coupe; J. Berkhof; A. A. Bouman; G. A. Meijer; C. J. J. Mulder

Disclosures

Aliment Pharmacol Ther. 2009;31(3):432-439. 

In This Article

Abstract and Introduction

Abstract

Background Guaiac-based faecal occult blood tests (g-FOBTs) are most commonly used in colorectal cancer (CRC) screening programmes. Faecal immunochemical tests (FITs) are thought to be superior.
Aim To compare performance of a g-FOBT and a quantitative FIT for detection of CRCs and advanced adenomas in a colonoscopy-controlled population.
Methods We assessed sensitivity and specificity of both FIT (OC-sensor) and g-FOBT (Hemoccult-II) prior to patients' scheduled colonoscopies.
Results Of the 62 invasive cancers detected in 1821 individuals, g-FOBT was positive in 46 and FIT in 54 (74.2% vs. 87.1%, P = 0.02). Among 194 patients with advanced adenomas, g-FOBT was positive in 35 and FIT in 69 (18.0% vs. 35.6%, P < 0.001). Sensitivity for screen relevant tumours (197 advanced adenomas and 28 stage I or II cancers) was 23.0% for g-FOBT and 40.5% for FIT (P < 0.001). Specificity of g-FOBT compared to FIT for the detection of cancer was 95.7% vs. 91.0%, P < 0.001) and for advanced adenomas (97.4% vs. 94.2%, P < 0.001).
ConclusionsFaecal immunochemical test is more sensitive for CRC and advanced adenomas. Sensitivity of FIT for screen relevant tumours, early-stage cancers and advanced adenomas, is significantly higher. Specificity of g-FOBT is higher compared with FIT.

Introduction

Colorectal cancer (CRC) is a leading cause of cancer death worldwide. Early detection is one of the most realistic approaches to reduce CRC-related death. Guaiac-based faecal occult blood tests (g-FOBTs) were already proposed for this purpose in the early 1970s.[1] Blood, shed into the colonic lumen by colorectal adenomas and carcinomas yields a positive g-FOBT because of the peroxidase-like activity of haeme in stool.[2] Screening programmes using g-FOBT have proven to reduce both incidence and mortality of CRC.[3–7] Yet, both clinical sensitivity (i.e. the percentage of tumours detected in a series of tumour positive patients that perform the test) and programme sensitivity (i.e. the percentage of tumours present in a population intended to screen that actually is detected) are suboptimal.[8,9]

More recently, the faecal immunochemical test (or FIT), has been introduced as an alternative to g-FOBT. The FIT selectively detects the human globin-protein in stool, making it specific to colonic blood loss, while globin from blood lost proximal to the colon will be degraded before entering the colon.[10,11] Several variants of FIT exist, some of which come with automated analysis and have quantitative outcomes, like the one used in the present study.[12]

Comparisons of different techniques to detect occult blood in stool have been performed since 1953.[13] Recent studies that compared g-FOBT and FIT in screening populations indicated superiority of FIT for the detection of both cancers and advanced adenomas.[8,14,15] To evaluate whether FIT can replace the most commonly used test (g-FOBT) in CRC screening, a comparative study design is needed. Both g-FOBT and FIT should be performed in parallel on the same stool samples.[14–16]

In addition, to appraise specificity of a test directly, all test negative individuals should undergo the test that is considered the gold standard, colonoscopy. Inherent to the design of screening studies, only FOBT-positive individuals underwent colonoscopy.[8,14,15,17] A large scale comparison of g-FOBT and FIT in a colonoscopy controlled population is still lacking. In the present study, test characteristics of both tests could be determined directly, as colonoscopy was performed in all included participants.

While population-based screening studies yield crucial information on programme sensitivity and acceptance of a test in the target population, often only small numbers of CRCs are detected.[18] Consequently, the power to stratify these cancers by stage is insufficient.[8,19] In a referral population, like in the present study, a higher prevalence of CRC and its precursor lesions will allow for stratification of FOBT result for different phases of the natural history of the disease.

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