Colorectal Cancer Screening Decision Based on Predicted Risk: Protocol for a Pilot Randomized Controlled Trial

Abstract

Background: Incidence of and mortality from colorectal cancer (CRC) can be effectively reduced by screening with the fecal immunochemical test (FIT) or colonoscopy. Individual risk to develop CRC within 15 years varies from <1% to >15% among people aged 50 to 75 years. Communicating personalized CRC risk and appropriate screening recommendations could improve the risk-benefit balance of screening test allocations and optimize the use of limited colonoscopy resources. However, significant uncertainty exists regarding the feasibility and efficacy of risk-based screening.

Objective: We aim to study the effect of communicating individual CRC risk and a risk-based recommendation of the FIT or colonoscopy on participants' choice of screening test. We will also assess the feasibility of a larger clinical trial designed to evaluate the impact of personalized screening on clinical outcomes.

Methods: We will perform a pilot randomized controlled trial among 880 residents aged 50 to 69 years eligible to participate in the organized screening program of the Vaud canton, Switzerland. Participants will be recruited by mail by the Vaud CRC screening program. Primary and secondary outcomes will be self-assessed through questionnaires. The risk score will be calculated using the open-source QCancer calculator that was validated in the United Kingdom. Participants will be stratified into 3 groups-low (<3%), moderate (3% to <6%), and high (≥6%) risk-according to their 15-year CRC risk and randomized within each risk stratum. The intervention group participants will receive a newly designed brochure with their personalized risk and screening recommendations. The control group will receive the usual brochure of the Vaud CRC screening program. Our primary outcome, measured using a self-administered questionnaire, is appropriate screening uptake 6 months after the intervention. Screening will be defined as appropriate if participants at high risk undertake colonoscopy and participants at low risk undertake the FIT. We will also measure the acceptability of the risk score and screening recommendations and the psychological factors influencing screening behavior. We will also assess the feasibility of a full-scale randomized controlled trial.

Results: We expect that a total sample of 880 individuals will allow us to detect a difference of 10% (α=5%) between groups. The main outcome will be analyzed using a 2-tailed chi-squared test. We expect that appropriate screening uptake will be higher in the intervention group. No difference in overall screening uptake is expected.

Conclusions: We will test the impact of personalized risk information and screening recommendations on participants' choice of screening test in an organized screening program. This study should advance our understanding of the feasibility of large-scale risk-based CRC screening. Our results may provide insights into the optimization of CRC screening by offering screening options with a better risk-benefit balance and optimizing the use of resources.

Trial registration: ClinicalTrials.gov NCT05357508; https://www.clinicaltrials.gov/study/NCT05357508.

International registered report identifier (irrid): DERR1-10.2196/46865.

Keywords: Switzerland; colorectal cancer screening; personalized screening; risk communication; screening behavior; shared decision-making.

Conflict of interest statement

Conflicts of Interest: M-AD has contributed to the development of Option Grid patient decision aids. EBSCO Information Services sells subscription access to Option Grid patient decision aids, and M-AD receives consulting income from EBSCO Health as well as royalties. RA is the main recipient of 2 grants related to colorectal cancer screening from the Swiss Cancer Research Foundation (Health Services Research; HSR-4366-11-2017) and the Swiss National Science Foundation (National Research Program 74; NFP74 407440_167519) “Smarter Health Care.” RA is also an unpaid member of the expert committee of the organized screening program in Bern, Switzerland, with an advisory role as expert. IL-V has received several grants evaluating (risk-based) colorectal cancer screening from nonprofit organizations.

©Ekaterina Plys, Jean-Luc Bulliard, Aziz Chaouch, Marie-Anne Durand, Luuk A van Duuren, Karen Brändle, Reto Auer, Florian Froehlich, Iris Lansdorp-Vogelaar, Douglas A Corley, Kevin Selby. Originally published in JMIR Research Protocols (https://www.researchprotocols.org), 07.09.2023.

Figures

Figure 1

Planned CONSORT (Consolidated Standards of Reporting Trials) diagram for the pilot randomized controlled trial. T1: intervention and secondary outcome data collection; T2: follow-up at 6 months (primary outcome and secondary outcome data collection).

Figure 2

Detailed procedure of the study. T0: recruitment and baseline data collection; T1: intervention and secondary outcome data collection; T2: follow-up at 6 months (primary outcome and secondary outcome data collection).