Depression is up to four times more common among individuals with cancer compared with the general population. Psychological therapies are effective in treating depression among patients in cancer care, but access is often delayed, which can exacerbate symptoms, increase dropout and reduce therapeutic effectiveness. This study evaluates the clinical and cost-effectiveness of a therapy preparation intervention (TPI) designed to enhance engagement and outcomes among patients awaiting psychological therapy in cancer care.

This study is a parallel-group, two-arm, multicentre, single-blind randomised controlled trial. A total of 150 adults (≥18 years) living with or beyond cancer and experiencing moderate-to-severe depression will be recruited from health services in the East Midlands region of England. Participants will be randomised (1:1) to receive either TPI plus treatment as usual (TAU) or TAU alone.

The primary outcome is depression severity measured using the Patient Health Questionnaire 9-items (PHQ-9) over a 24-week follow-up. Secondary outcomes include anxiety, functioning, mental well-being, patient activation, readiness for change, health-related quality of life and health economics, and therapy engagement including attendance and dropout. Hope and in-session patient activation, assessed using recorded treatment preparation sessions, will be explored as additional mechanistic variables. Health economic outcomes will be assessed at baseline and 24 weeks. Data will be collected via online or telephone surveys at baseline, and at 4, 8, 12 and 24 weeks post randomisation. Qualitative interviews with a subset of participants will explore intervention experiences, analysed using reflexive thematic analysis.

Ethical approval has been obtained from the Health Research Authority and National Health Service Research Ethics Committee (Bromley) (REC reference: 24/LO/0610). Findings will be disseminated through peer-reviewed journals, academic conferences and clinical and patient networks.

ISRCTN registry: ISRCTN13692666, registered on 18 October 2024.