Blood-based cell-free DNA for addressing colorectal cancer screening disparities: a study protocol for a randomised...

Colorectal cancer (CRC) screening reduces cancer incidence and mortality, but participation rates are suboptimal in the USA and associated with inequities in CRC outcomes for lower income and many racial/ethnic minoritised groups. A novel, US Food and Drug Administration-approved cell-free tumour DNA (cfDNA) blood test has the potential to improve screening rates, but the impact of offering this test on participation, including among populations at disproportionately increased risk for inequities in CRC outcomes, has not been studied. We designed a small effectiveness randomised controlled trial (RCT) comparing a strategy of offering expanded options for CRC screening including a cfDNA test to a strategy of standard usual care options for screening.

This study is a two-arm, parallel-group RCT, with 1:1 randomisation of 340 patients to an intervention group versus a usual care group for CRC screening. Participants will include patients who are aged 45-75, not up-to-date with CRC screening and attending a routine primary care visit at Family Health Centers of San Diego, a Federally Qualified Health Center (FQHC) system serving a racial and ethnically diverse, low-income patient population. The intervention group will be offered choice of colonoscopy, at home faecal immunochemical test (FIT) or a combination of in clinic cfDNA and at home FIT. The usual care group will be offered a choice of colonoscopy or at home FIT. Both groups will receive education on the importance of screening and reminders to complete testing. Primary outcome is CRC screening completion within 60 days of enrolment, summarised as the proportion of all patients randomised by group, compared via a χ² test of proportions. Secondary outcomes will include: number of abnormal results for each test modality, test results, number of patients with abnormal tests referred for abnormal test follow-up, and number of patients who completed colonoscopy within 90 days of an abnormal non-invasive test result.

This study was approved by the University of California, San Diego Office of Institutional Review Board Administration (811489). A waiver of documented (signed) consent was approved by and will allow for a pragmatic design that mimics usual care, in which all patients will be offered all options for CRC screening. Main results will be disseminated to trial participants via reporting of test results and study publication.

NCT06929481.