High uptake is vital to population-based screening. BowelScreen (Irelands national organised population-based colorectal cancer screening programme) has not achieved recommended screening uptake targets. In Ireland sending the test kit in the screening invitation reminder may be an important strategy in targeting non-responders and would address a key difference between Ireland and other international screening programmes with higher uptake. In addition, few studies have focused on behavioural barriers to screening participation. Founded upon the MRC Guidelines for the Development of Complex Interventions, our systematic, theoretically-informed investigation of FIT screening participation has begun to identify behavioural antecedents to screening participation in Ireland. This study will implement a multilevel evidence-based, theoretically-informed intervention which includes the automatic inclusion of the test kit in the screening reminder, alone and in combination with an intervention to influence individuals' screening participation. This multilevel intervention will provide recommendations for the screening invitation delivery, potentially bringing the programme closer to recommended uptake targets (50%) and in the long-term influence reductions in bowel cancer incidence and mortality in Ireland.

To achieve population-level health gains, colorectal cancer screening programmes require high uptake. Guidelines recommend uptake of 65%-75%. In Ireland, faecal immunochemical test (FIT)-based screening uptake is considerably lower than this (around 40%), despite FIT being recommended as the screening test of choice given its potential to deliver higher uptake than other tests. As well as being suboptimal overall, uptake in Ireland is significantly lower among males and lower socioeconomic groups the very groups at higher underlying risk of colorectal cancer. While improving overall uptake is important, focus is also needed on reducing differentials in uptake; left unchecked these may lead to further disparities in health outcomes among those most at risk.

The main difference between Ireland's screening programme and programmes with higher uptake is that BowelScreen does not send the test kit with the screening invitation: invitees are required to contact a call-centre, consent to participate and request the kit. Uptake in Ireland is 10-30% lower than Scotland, the Netherlands and England and, indeed, in a pilot screening programme in Dublin that also sent the test automatically.

Internationally, various strategies to improve uptake have been tested. Some studies report increases using advance notification letters, postal mailing of home-based testing kits, and telephone contacts but many studies have been negative. Recent UK research points to potential in intervening among non-responders to the initial screening invitation, but few intervention studies have focussed on non-responders. An important limitation of existing studies is that most investigators failed to base their interventions on an understanding of what influences individuals' decisions about screening participation/non-participation.

A range of barriers to uptake have been identified and include fatalism, poor knowledge, being poorly informed about cancer and screening and holding negative attitudes, beliefs and emotions towards FIT screening. Following the MRC Framework for the Development of Complex Interventions and being theoretically informed, this work has the explicit intention of informing future interventions.

This proposal seeks to test efficacy in increasing uptake of two interventions among non responders: 1) including a test kit with the current reminder, and 2) an evidence-based and theoretically informed behavioural intervention (e.g. modified reminder letter, modified accompanying leaflet).

Inclusion Criteria:

All new invitees of Irelands National BowelScreen Programme Individuals aged 60-64

Exclusion Criteria:

All individuals who are within the screening age range of Irelands national bowel screening programme are eligible to be included.