Immunochemical faecal occult blood testing to screen for colorectal cancer: can the screening interval be extended?
Menée à partir de données néerlandaises portant sur 4 523 participants à un programme de dépistage du cancer colorectal comportant un test immunochimique de recherche de sang dans les selles (âge : 50 à 74 ans), cette étude évalue, en fonction de la valeur seuil de positivité et du point de vue du taux de détection d'adénomes colorectaux de stade avancé ou de cancers colorectaux de stade précoce, la possibilité d'augmenter le délai entre deux examens de dépistage
Objective : Colorectal cancer (CRC) screening programmes based on faecal immunochemical testing for haemoglobin (FIT) typically use a screening interval of 2 years. We aimed to estimate how alternative FIT strategies that use a lower than usual positivity threshold followed by a longer screening interval compare with conventional strategies.
Methods : We analysed longitudinal data of 4523 Dutch individuals (50–74 years at baseline) participating in round I of a one-sample FIT screening programme, of which 3427 individuals also participated in round II after 1–3 years. The cohort was followed until 2 years after round II. In both rounds, a cut-off level of ≥50 ng haemoglobin (Hb)/mL buffer (corresponding to 10 µg Hb/g faeces) was used, representing the standard scenario. We determined the cumulative positivity rate (PR) and the numbers of subjects diagnosed with advanced adenomas (N_AdvAd) and early stage CRC (N_earlyCRC) in the cohort over two rounds of screening (standard scenario) and compared it with hypothetical single-round screening with use of a lower cut-off and omission of the second round (alternative scenario).
Results : In the standard scenario, the cumulative (ie, round I and II combined) PR, N_AdvAd and N_earlyCRC were 13%, 180% and 26%, respectively. In alternative scenarios using a cut-off level of respectively ≥11 and ≥22 ng/HbmL buffer (corresponding to 2 and 4 µg Hb/g faeces), the PRs were 18% and 13%, the N_AdvAd were 180 and 162 and the N_earlyCRC ranged between 22–27 and 22–26.
Conclusions : The diagnostic yield of FIT screening using a lowered positivity threshold in combination with an extended screening interval (up to 5 years) may be similar to conventional FIT strategies. This justifies and motivates further research steps in this direction.
Gut , résumé, 2016