Faecal occult blood loss accurately predicts future detection of colorectal cancer. A prognostic model
Menée aux Pays-Bas à partir de données portant sur 265 881 personnes ayant participé à trois sessions d'un programme biennal de dépistage du cancer colorectal et dont les résultats des tests FIT sont négatifs pour les deux premières sessions, cette étude évalue la performance d'un modèle, basé notamment sur des critères démographiques (âge et sexe des participants) et la concentration d'hémoglobine dans les selles lors des deux premières sessions, pour prédire le risque d'adénome de stade avancé ou de cancer colorectal à la troisième session de dépistage
Objectives : To examine the prognostic potential of repeated faecal haemoglobin (F-Hb) concentration measurements in faecal immunochemical test (FIT)-based screening for colorectal cancer (CRC).
Design Prognostic model.
Setting : Dutch biennial FIT-based screening programme during 2014–2018.
Participants : 265 881 participants completing three rounds of FIT, with negative test results (F-Hb <47 µg Hb/g faeces) in rounds 1 and 2.
Interventions : Colonoscopy follow-up in participants with a positive FIT (F-Hb ≥47 µg Hb/g faeces).
Main outcomes : We evaluated prognostic models for detecting advanced neoplasia (AN) and CRC in round 3, with as predictors, participant age, sex, F-Hb in rounds 1 and 2, and categories/combinations/non-linear transformations of F-Hb. Primary evaluation criteria included: risk prediction accuracy (calibration), discrimination of participants with versus without AN or CRC (optimism-adjusted C-statistics, range 0.5–1.0), the degree of risk stratification and C-statistics in external validation.
Results : Among study participants, 8806 (3.3%) had a positive FIT result, 3254 (1.2%) had AN detected and 557 (0.2%) had cancer. F-Hb concentrations in rounds 1 and 2 were the strongest outcome predictors, with adjusted ORs of up to 9.4 (95% CI 7.5 to 11.7) for the highest F-Hb category. Risk predictions matched the observed risk for most participants (calibration intercept −0.008 to −0.099; slope 0.982–0.998), and discriminated participants with versus without AN or CRC with C-statistics of 0.78 (95% CI 0.77 to 0.79) and 0.73 (95% CI 0.71 to 0.75), respectively. The predicted risk ranged from 0.4% to 36.7% for AN and from 0.0% to 5.5% for CRC across participants. In external validation, the model retained similar discrimination accuracy for AN (C-statistic 0.77, 95% CI 0.66 to 0.87) and CRC (C-statistic 0.78, 95% CI 0.66 to 0.91).
Conclusion : Participants at lower versus higher risk of future AN or CRC can be accurately identified based on their age, sex and particularly, prior F-Hb concentrations. Risk stratification should be considered based on this information.
Gut , article en libre accès, 2021