Colorectal cancer screening in Flanders: Advances in personalised screening
Authors: W. van de Veerdonk, G. Van Hal, M. Peeters, I. Brabander, G. Silversmit, S. Hoeck
Journal: Annals of Oncology (2018)

Introduction: The quantitative faecal immunochemical test (FIT) is used in the Flemish colorectal cancer screening programme to detect precancerous lesions and colorectal cancer (CRC). Current CRC screening programmes are based upon a binary FIT result. However, a substantial part of the positive FITs followed up by colonoscopy are found negative (normal). And several participants are not followed up by colonoscopy within 6 months after a positive FIT. Therefore, this study evaluates the possibility of establishing a risk profile based upon a combination of the quantitative FIT, age and gender to gain more insight into tailored risk prediction and communication of risk to general practitioners (GPs) and/or participants. Methods: In this retrospective study, data was used of 57,421 participants who underwent a colonoscopy after a positive FIT in the Flemish CRC screening programme between October 2013 until July 2016. Analyses were performed with multinomial logistic regression to predict the probability of normal or noncancerous lesions, precancerous lesions, in situ or invasive cancers. Additionally, odds ratios (OR) were established to visualize the magnitude of the differences between risk profiles within a population with positive FIT, based upon a combination of the quantitative FIT, age and gender. Results: The amount of false positive FIT results followed up by colonoscopy is ∼27%, where ∼20% are not followed up at all by colonoscopy within 6 months after a positive FIT. Based on our risk profile calculation, we found a significant difference between the risk of having a normal outcome, a precancerous lesion, an in situ or an invasive cancer. For example, the detection of invasive cancer was 58 (OR) times more likely in a male of 74 years old with a FIT result of ≥ 1,000 ng/ml compared to a woman of 56 years old with a FIT result of 75 ng/ml. Conclusion: The differences in precancerous lesions or CRC according to our calculated risk profiles, justifies an approach where participants with a positive FIT are not all treated in the same way, based on a binary FIT. Participants and/or their GPs should be informed about individual risks. This will promote informed decision to an extent where participants and/or professionals can make decisions on follow-up. How to communicate this personalised information to participants needs to be discussed and tested. Contrary to the participant, professionals such as GPs should be provided with extra insight in the risk differences per patient, which supports their clinical decision making. The approach above could be extended by adding simple risk factors such as BMI, diet, alcohol intake, family history etc., creating the opportunity to more accurately discriminate between participants with a normal outcome, precancerous lesion, in situ or invasive cancer. Colonoscopy follow up based upon the quantitative FIT, combined with age, gender and additional risk factors instead of upon a binary FIT result only, will probably increase accuracy.