An interventional study of Tailored reminder letter in Health Behavior, Breast Cancer Screening and Mammography, sponsored by Universiteit Antwerpen. Completed at 2 sites in Belgium. Open to participants aged 50 Years to 69 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-03-16.
Sponsored by Universiteit Antwerpen · Not applicable, Interventional, and Screening
The goal of this trial is to learn whether a culturally and linguistically tailored reminder letter can increase participation in the Flemish Breast Cancer Screening Program among women who previously did not attend screening. The study also examines whether the effect differs between socioeconomic groups.
The main questions it aims to answer are:
Researchers compare two groups:
Participation in screening within 40 days of the invitation is measured using the program's registry.
Participants are women aged 50-69 years who had previously been invited but had never attended screening. The reminder letter is sent as part of routine screening communication, and no additional medical procedures are involved.
This study aims to evaluate the effectiveness of a culturally and linguistically tailored reminder letter in increasing mammography uptake within the Flemish Breast Cancer Screening Program (BCSP) among women who previously did not attend screening. The objectives are to:
Study Setting:
The study is embedded within the Flemish BCSP, which is coordinated by the Centre for Cancer Detection (CvKO). The BCSP provides biennial screening mammography, free of charge, to eligible individuals aged 50-69 years registered as female in the Belgian national registry. Recruitment occurs through the routine program invitation process, where eligible individuals receive a mailed invitation letter indicating the time and location of their screening appointment.
Study design:
This study is a two-arm, parallel-group, superiority, randomized controlled trial (RCT) with partial blinding.
Study arms:
Detailed descriptions of study Arms and Intervention, Study Design (Masking, Allocation), Outcome Measures and Eligibility are provided in the designated sections.
Statistical analysis:
The primary analysis compares BC screening uptake between the intervention and control arms in the overall study population. The effect of the intervention is quantified using odds ratios (ORs) with corresponding 95% confidence intervals (CIs). Statistical significance is assessed using the likelihood-ratio chi-square test (x²), with two-sided p-value \< 0.05. Stratified analyses are conducted by socioeconomic status (SES), age group, province of residence, and type of mammographic unit. Analyses are performed according to both intention-to-treat (ITT) and per-protocol (PP) principles, with ITT as the primary analytic approach and PP as a sensitivity analysis. The ITT population comprises all randomized participants, excluding records removed before analysis during routine quality control procedures (e.g., duplicate system entries or invalid identifiers). The PP population comprises participants who receive the allocated intervention as planned and for whom complete outcome data is available. Exclusion criteria for the PP analysis comprise withdrawal or opt-out from the BCSP prior to receipt of the assigned communication strategy and documented logistical issues affecting letters delivery in either study arm. Deaths or emigrations occurring prior to participation are not specifically addressed in the PP definition as they are assumed to be evenly distributed between study arms, in line with routine cross-checks with demographic registries. No multivariable adjusted analyses are performed. Stratified analyses are interpreted descriptively, and no formal correction for multiple comparisons is applied.
228 studies on the registry are indexed under Health Behavior; 95 are open to participants now.
This study's enrollment of 7,947 is above the median of 114 across 196 interventional studies indexed under Health Behavior.
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Individual-level criteria:
Area-level criteria:
To increase the inclusion of socioeconomically vulnerable individuals while maintaining representation from the broader screening population, participants are selected from the list of individuals invited at mammographic units located in municipalities with high deprivation scores, defined as meeting at least two of the following criteria:
Exclusion Criteria
Participants allocated to the intervention arm receive two mailed communications: (1) the standard Breast Cancer Screening Program invitation letter, sent approximately three weeks before the scheduled screening appointment (±4 days); (2) an additional culturally and linguistically tailored reminder letter, sent approximately one week before the scheduled appointment (±4 days). The tailored reminder letter is specifically designed to address linguistic and cultural barriers that may affect screening participation.
Behavioral: Tailored reminder letter
Participants allocated to the control arm receive the standard BCSP invitation letter only, approximately three weeks before the scheduled screening appointment (±4 days), with no additional reminder. The content of the standard invitation letter is publicly available on the website of the Centre for Cancer Detection (CvKO).
The intervention development process is described in detail elsewhere (DOI: 10.1186/s13690-025-01591-7). A brief summary is provided below: The tailored reminder letter was developed using an iterative, participatory approach between April and October 2023. Three focus group discussions with 19 eligible women identified barriers to screening participation and limitations of the existing invitation letter. Based on these findings, a draft letter was refined through a Delphi process involving experts and stakeholders familiar with the screening program and target population. The letter was then improved during a co-creation session with 14 eligible women and validated through a final expert member check. The final reminder letter was designed for a low-literate audience, using simplified language and visual elements. It included essential appointment information and a QR code linking to translations in multiple languages to improve accessibility for linguistically diverse populations.
Screening uptake
Screening uptake, defined as the proportion of invited individuals who attend a mammographic appointment within the pre-specified time frame.
Time frame: Within 40 days after invitation letter is sent.
Documents are hosted by the registry — open the source record to download them.
Plan to share: Yes — The study protocol is made publicly available. Aggregated study results may be shared upon reasonable request. Individual participant data are derived from screening and health insurance registries and are subject to Belgian data protection regulations, requiring specific authorization from the competent authorities.
Supporting information: Study protocol
This study is completed, as verified in Mar 2026. You cannot join it, but the record below documents what was studied.
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