Result card

  • CUR11: What aspects of the burden of CRC are targeted by CRC screening with FIT?
English

What aspects of the burden of CRC are targeted by CRC screening with FIT?

Authors: Mirjana Huic, Eleftheria Karampli, Silvia Florescu, Cipriana Mihaescu-Pintia

Internal reviewers: Laura Cacciani, Sophie Brunner, Esther Kraft

CRC screening in general aims to reduce morbidity and mortality from CRC through both, prevention (by the removal of adenomas before they become malignant) and earlier diagnosis of CRC (at early, curable stage). CRC is particularly suitable for screening due to natural course of disease (adenoma-carcinoma sequence). When detected in the adenoma-phase, removal of the adenoma prevents the incidence of CRC; when detected as an early-stage cancer, prognosis is considerably better than for late-stage cancer. An increase in incidence in the target age range may be observed immediately after the introduction of a CRC screening programme, however, incidence rates should return to background level at re-screening apart from the advancement of the age of diagnosis by screening {43}. For the individual, CRC screening in general can prevent the negative impact of CRC morbidity on quality-of-life {44}. As cancer treatment also represents a significant economic cost for the health system, CRC screening also results in cost-savings ({45} cited by {5}).

There are various methods available for colorectal cancer screening (see Result card CUR22). They can be broadly divided into endoscopic and radiologic methods (for example colonoscopy) and stool-based tests (guaiac-based or immunochemical Faecal occult blood tests - FOBTs, Faecal DNA testing) {42}. Routine screening of stool for occult blood may facilitate early detection.

Guaiac-based Faecal Occult Blood (gFOBT) tests are those mostly studied in RCTs as screening test for CRC and are an established screening strategy for CRC. Several large randomized studies have demonstrated a reduction in cancer-related mortality. In three systematic reviews of RCTs using gFOBT for CRC screening, a reduction of 14 - 16 % in CRC mortality was found {46, 47, 48}  as referenced in {49}. In a matched-cohort study in Scotland, a reduction of 10% in CRC mortality was found {50}. The disadvantage of screening with gFOBT is relatively low sensitivity (many negative colonoscopies). gFOBT sensitivity is only around 50% for carcinoma; specificity for tumour or polyp around 25-40%. In FOBT screen-positive patients in the UK National Bowel Cancer Screening Programme (NHS BCSP) about 10% have cancer, 40% have adenomas and the colon is normal in 50%. False positive results of gFBOT tests are related to ingestion of red meat, iron, aspirin, upper GI bleeding. False negatives can be produced by vitamin C ingestion, intermittent bleeding. The dietary requirements for people preparing for screening with gFBOT may limit patient acceptance {51}.

As it the case with gFOBTs, a range of immunochemical tests are available with varying sensitivity and specificity (5). It has been argued that, since efficacy of gFOBT has already been demonstrated, decisions on screening with FITs can be based on the performance characteristics of the tests (sensitivity, specificity, positive predictive values) {44}. Performance characteristics are addressed in subsequent domains FITs can also be used as a "reflex" test, after primary screening with gFOBT. Available data on this screening strategy, from either research studies or screening programmes is limited {44} .

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Huic M et al. Result Card CUR11 In: Huic M et al. Health Problem and Current Use of the Technology In: Jefferson T, Cerbo M, Vicari N [eds.]. Fecal Immunochemical Test (FIT ) versus guaiac-based fecal occult blood test (FOBT) for colorectal cancer screening [Core HTA], Agenas - Agenzia nazionale per i servizi sanitari regionali; 2014. [cited 21 June 2021]. Available from: http://corehta.info/ViewCover.aspx?id=206

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