Aims: To evaluate whether a multicomponent general practice-led intervention increased bowel cancer screening participation among patients eligible for Australia’s National Bowel Cancer Screening Program.
Methods: We conducted a two-arm, cluster-randomised hybrid type 2 effectiveness-implementation trial across four Primary Health Network (PHN) sites in New South Wales, Queensland and South Australia. Practices were randomised to intervention or usual care. The intervention included a decision-support tool, electronic point-of-care prompts, National Cancer Screening Register integration, educational resources and implementation support from PHN-based Clinical Trial Coordinators. Aggregated practice-level data were collected monthly from September 2024 to May 2025. The primary outcome was the proportion of active eligible patients with a completed immunochemical faecal occult blood test in the previous two years.
Results: Ninety-three practices were recruited and 83 completed the trial (41 intervention, 42 usual care); 62 practices were included in the final analytical sample. Among people aged 45 to 74 years, mean screening rates increased from 262.9 to 270.3 per 1,000 eligible patients in intervention practices and from 272.9 to 281.9 per 1,000 in usual care practices. In adjusted analyses, screening was higher during the intervention period than the pre-intervention period (RR 1.05, 95% CI 1.03 to 1.06, p<0.0001). Trial arm was not independently associated with screening participation (RR 0.99, 95% CI 0.85 to 1.15).
Conclusion: This large-scale trial demonstrates the feasibility of embedding colorectal cancer screening support within routine Australian general practice. Although screening participation increased during the study period, no independent intervention effect was observed. The findings contribute important evidence on how screening interventions can be integrated into existing practice systems and inform future efforts to strengthen participation in the National Bowel Cancer Screening Program.