Testing interventions to increase participation in the Australian National Bowel Cancer Screening Program among...

Bowel cancer screening using faecal immunochemical tests (FIT) can detect early signs of bowel cancer and pre-cancerous adenoma. Early detection enables early diagnosis and treatment thereby reducing associated morbidity and mortality from bowel cancer. The National Bowel Cancer Screening Program (NBCSP) in Australia mails free FIT kits to eligible people aged 50-74 every 2 years; currently, only 42% of people return their kits. People aged 45-49 are eligible but need to request their kit, and as this has been recently introduced, participation data are not yet available. Many people never participate despite multiple invitations; 'persistent never screeners' are defined as people who have received at least three NBCSP kits but never returned any. This trial aims to increase screening participation among persistent never screeners by modifying invitation materials.

Eligible participants (persistent never screeners due for pre-invitation letters) will be randomly assigned to one of three trial arms over a 5-week enrolment period and followed up for 6 months. The trial will compare kit return between two intervention arms and a control arm to determine effectiveness.

Individuals who are defined as persistent never screeners are eligible for the NBCSP and are due for a pre-invitation letter during the trial period.

1. A modified pre-invitation letter will be sent identifying that they have not yet screened with the program and that they are not up to date with their screening. It will highlight that they are at increased risk of bowel cancer and provide a QR code and weblink to a site that allows them to order a NBCSP kit. 2. A kit with revised invitation materials, including: a modified letter highlighting increased risk from not completing previous kits, a QR code linking to information addressing common screening barriers, and a modified outer envelope removing bowel cancer information from the front and adding 'Important information about your health inside' in seven languages.

Standard NBCSP pre-invitation, invitation material and kit.

This trial will provide evidence on whether modified invitation and pre-invitation materials can improve screening participation among persistent never-screeners, a consistently hard-to-reach subgroup in cancer screening programs globally.