How Survivors of Colorectal Cancer Experience ctDNA Testing and Fear of Recurrence

Circulating tumor DNA (ctDNA) is a novel prognostic biomarker indicating minimal residual disease and high recurrence risk. In three randomised DYNAMIC trials, ctDNA was used to guide adjuvant chemotherapy (ACT) for early-stage colorectal cancer. While clinical applications of ctDNA are being established, the psychosocial impact, particularly on fear of cancer recurrence (FCR), is less understood.

To explore the psychosocial impact, especially FCR, of ctDNA-informed ACT decisions among a subset of DYNAMIC trial participants.

A qualitative study using semi-structured interviews was conducted with English-speaking, recurrence-free patients from the DYNAMIC trials, across ctDNA-guided and standard-care groups. Interviews were audio-recorded, transcribed, and thematically analyzed.

Twenty-eight patients participated (median age 64 years; 64% male; equal numbers with early-stage colon and rectal cancer). Eight received a positive ctDNA result, 11 a negative result, and 9 were blinded to their result. Three themes emerged: (1) Limited Understanding of ctDNA Results: Many patients had poor recall or understanding of the test and its prognostic meaning. (2) Trust in Clinician-Led Decision-Making: Strong reliance on clinicians to interpret results and guide ACT decisions. (3) FCR - Episodic, Context dependent: Fear was intermittent, typically arising around scans, new symptoms, or others' diagnoses, and was not influenced by ctDNA knowledge.

In this cohort, on average 5 years from trial entry, ctDNA-informed ACT decisions did not increase FCR or cause long term psychosocial harm. As ctDNA testing enters routine practice, clear communication strategies will be essential to ensure patients understand results while maintaining trust in clinician-patient decision-making.