Result card

  • EFF10: How does FIT for CRC screening modify the progression of adenomas and CRC?

How does FIT for CRC screening modify the progression of adenomas and CRC?

Authors: Jesús González-Enríquez, Francesca Gillespie, Stefania Lopatriello, Iñaki Imaz

Internal reviewers: Pseudo125 Pseudo125

Refer to domain search and domain methodology section.

Compared with standard gFOBT, current evidence from systematic reviews and clinical trials indicates a higher sensitivity for the detection of CRC and advanced adenomas, and higher rates of detection for CRC and advanced adenomas (refer to EFF 12, EFF 20, EFF 22) {10,15,16,17,18}. A superior sensitivity and detection rate of adenomas is a distinguishing performance characteristic of FIT compared with gFOBT, thus proving a greater preventive capacity. If all advanced adenomas and CRC detected are removed progression of lesions could be avoided. The endoscopic removal of pre-malignant lesions also reduces the incidence of CRC by stopping the progression to cancer.

TNM stage distribution of CRC detected in screening programmes using FIT shows an early detection, and early treatment of colorectal lesions before they become symptomatic can reduce morbidity and mortality associated to CRC. 

A recent Italian screening programme by biennial immunochemical FOBT reported a retrospective comparison of cancer rate and stages between average risk screening participants and those who did not participate in the screening programme. Although the overall cancer rate was similar in the two populations (1.23 versus 1.20 per 1000 person-years), there were significant differences in TNM stage distribution between the two groups (stage III–IV cancers 0.24 versus 0.74 per 1000 respectively, p = 0.009). This large cross-sectional study reported that colorectal cancers detected by immunochemical FOBT screening are identified at an earlier pathological stage, with significant prognostic and treatment cost advantages to the populations screened {9}. A major goal of a colorectal cancer mass screening programme is to diagnose cancer at an earlier stage, thus permitting curative treatment at lower cost, as the prognosis and cost of late-stage cancer at diagnosis are quite different. In this screening programme most of the screen-detected cancers were diagnosed at a very early stage; 81 per cent were TNM stage I or II and were therefore treated with curative intent, compared with only44·0 per cent of cancers detected within the same age range in the non-screened population.

It could be a case of lead time bias. Those participants who do not participate in the screening programme are diagnosed after they have signs and symptoms of cancer, so they are in advances TNM stages. If the screening program does not modify the progression, the increase in survival time makes it seem as though screened patients are living longer when that may not be happening (the date of diagnosis is earlier for screened patients).

González-Enríquez J et al. Result Card EFF10 In: González-Enríquez J et al. Clinical Effectiveness 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 16 June 2021]. Available from: