Colorectal cancer screening participation in First Nations populations worldwide: a systematic review and data synthesis.

Background: First Nations populations have poorer colorectal cancer (CRC) survival compared to non-First Nations populations. Whilst First Nations populations across the world are distinct, shared experiences of discrimination and oppression contribute to persistent health inequities. CRC screening improves survival, however screening rates in First Nations populations are poorly described. This study seeks to define participation rates in CRC screening in First Nations populations worldwide. Methods: A systematic literature search was conducted of PubMed, Embase, Cochrane Library, CINAHL, MEDLINE, grey literature, national registries and ClinicalTrials.gov. All sources were searched from their inception date to 18 February 2024. Studies were included if they reported CRC screening rates in adult (≥18 years) First Nations populations. We aimed to undertake a meta-analysis if there were sufficient data. Quality of papers were assessed using the Joanna Briggs Institute (JBI) appraisal tool. The study was registered with PROSPERO, CRD42020210181. Findings: The literature search identified 1723 potentially eligible published studies. After review, 57 studies were included, 50 from the United States (US), with the remaining studies from Australia, Aotearoa New Zealand (NZ), Canada, Dominica and Guatemala. Additionally, eleven non-indexed reports from national programs in Australia and NZ were included. There were insufficient data to undertake meta-analysis, therefore a systematic review and narrative synthesis were conducted. CRC screening definitions varied, and included stool-based screening, sigmoidoscopy and colonoscopy. US First Nations screening rates ranged between 4.0 and 79.2%, Australia reported 10.6-35.2%, NZ 18.4-49%, Canada 22.4-53.4%, Guatemala 2.2% and Dominica 4.2%. Fifty-five studies were assessed as moderate or high quality and two as low quality. Interpretation: Our findings suggested that there is wide variation in CRC screening participation rates across First Nations populations. Screening data are lacking in direct comparator groups and longitudinal outcomes. Disaggregation of screening data are required to better understand and address First Nations CRC outcome inequities. Funding: None.