New Stool Screening Tests for Colorectal Cancer

Abstract

Background/Aims: The purpose of this review is to clarify the place of new-technology stool tests in screening for colorectal neoplasia. Findings: New technologies have been based on blood and cellular products of neoplasia. Fecal occult blood tests (FOBTs) based on guaiac (i.e. GFOBTs) have been proved to be effective, but their impact on mortality is modest. When GFOBTs are reconfigured to provide improved sensitivity for cancer, their specificity often becomes unacceptable. Fecal immunochemical tests (FITs) targeting the human hemoglobin molecule have been shown to have better sensitivity for neoplasia without an unacceptable deterioration in specificity. The new stool-sampling technologies for FITs also improve population participation rates in screening. Most recently, quantitative FITs have become available; these provide flexibility for the end-user as a desired sensitivity: specificity ratio can be selected that is feasible in the context of available colonoscopic resources. A multi-target fecal DNA test, comprising a test for undegraded DNA and certain common mutations, was found more sensitive for cancer, but not for adenoma, than the early GFOBTs. A more recent version including an epigenetic marker for the vimentin gene has further improved sensitivity for cancer, but performance relative to GFOBT or FIT is not clear. These ‘fecal DNA tests’ have not proved to be more specific for neoplasia than tests that detect blood. Conclusions: FIT should replace GFOBT as the first test in two-step screening of large populations. It is not yet clear that tests targeting nonhemoglobin molecular events provide a clear advantage over FIT.

Experience with a wipe guaiac-based faecal occult blood test as an alternative test in a bowel screening programme

“…5 Thus, it was decided that a gFOBT was required as an alternative test. Interestingly, those questioned at the focus group meeting stated that, if a participant could manage their own personal hygiene, but had failing sight or manual dexterity difficulties, the wipe gFOBT would be the most suitable alternative.…”

Improvements in colorectal cancer screening programmes - quantitative immunochemical faecal occult blood testing - how to set the cut-off for a particular population

“…However patients having incomplete colonoscopies without the aforementioned additional investigations were excluded (Table 2). Complete colonoscopy was de- Positive FOBT 122 [15] Family history of CRC 65 [8] Anaemia 81 [10] Abdominal pain 57 [7] Weight loss 73 [9] Change of bowel habit 106 [13] Other 16 [2] fined as intubation to the lower caecum or intubation up to an obstructing neoplasm.…”

“…[5][6][7] ) such as France and Italy while other countries will introduce it ie. Slovenia, The Netherlands and Germany.…”

“…9 ) testing has become available, the advantage of which is to obtain optimum test sensitivity and specificity for a particular population by setting a cut-off value. A new more sophisticated sampling technology in immunochemical testing may lead to the growing participation of the population in the screening programme as well 7 . Some studies have also indicated greater patient participation in screening using q-FIT than g-FOBT [10][11][12] .…”

Analysis of specific serum markers of colon carcinoma using a Bhattacharyya-based support vector machine

“…Additionally, endoscopy performed using a fibrocolonoscope or electronic colonoscope, is commonly used in the clinical setting. This method can be used to directly observe colonic lesions and perform qualitative biopsy (Young and Cole, 2007). Endoscopy is the most effective means to identify and diagnose colon carcinoma and is also the most common and accurate method for early-stage diagnosis.…”