A breast cancer diagnosis can lead to significant anxiety, and for many survivors, this anxiety continues well beyond the end of treatment. While standard anxiety therapies are helpful for some, these therapies often fall short for breast cancer survivors due to an individual's unique experience-particularly changes in how survivors perceive and relate to the body, a process known as interoception.

The study will evaluate the feasibility and acceptability of a novel interoceptive training approach called ADIE Therapy. ADIE Therapy trains participants to better recognise bodily signals, and has shown promising results in reducing anxiety in non-cancer populations. The aim of the study is to assess the acceptability and feasibility of ADIE Therapy for breast cancer survivors.

Anxiety is a common and often long-lasting psychological consequence of a breast cancer diagnosis. Post-cancer anxiety frequently co-occurs with somatic symptoms such as persistent pain and fatigue. For many individuals, feelings of anxiety do not resolve with the completion of cancer treatment and can persist for months or even years. For yet others, anxiety increases after cancer treatment has ended. Although standard therapies-such as cognitive behavioural therapy or pharmacological interventions-can be effective for some, these interventions do not adequately address the needs of all breast cancer survivors. This may be due, in part, to the unique physical and emotional challenges faced by this group, including changes in the way internal bodily sensations are experienced and interpreted.

Interoception refers to the process by which the nervous system senses, interprets and integrates information from inside the body. ADIE Therapy - which stands for Aligning Dimensions of Interoceptive Experience - has shown promise as a novel interoceptive intervention to reduce anxiety and somatic symptoms in non-cancer populations. ADIE Therapy uses simple, biofeedback-based tasks to enhance precision in perceiving cardiac interoceptive signals.

The primary aim of the study is to demonstrate the acceptability and feasibility of ADIE Therapy for survivors of primary breast cancer. A mixed-methods approach will be used to evaluate the feasibility and acceptability of ADIE Therapy, incorporating both quantitative and qualitative measures. Secondary aims include ascertaining whether ADIE Therapy leads to improvements in interoceptive measurements (including self-reported interoceptive sensibility and objective interoceptive markers), anxiety symptoms (including generalised and cancer-specific anxiety), depressive symptoms, somatic symptoms, and body mindsets. Additional secondary aims include exploring the feasibility of incorporating blood and saliva collection into the ADIE-BC research protocol, which could facilitate assessment of biomarker outcomes in a future randomised controlled trial of ADIE-BC.

Participants will be recruited through charity and foundation partners, as well as through community settings. ADIE Therapy involves the administration of simple biofeedback-based tasks designed to progressively improve objective interoceptive accuracy, specifically through cardiac interoceptive exercises. A schedule of six interoceptive training sessions will be agreed with each participant, with the option to complete intermediate training sessions either in-person or at home. During each training session, participants will complete the cardiac interoceptive tasks with active feedback, before and after a 2-to-3-minute period of self-directed exercise, intended to elevate heart rate. The resulting cardiovascular arousal aims to amplify sensations associated with the heartbeat, thereby facilitating perception during interoceptive tasks. In addition to training, participants will complete three interoceptive assessments conducted at pre-training, midpoint (Week 4), and post-training (Week 7), each scheduled within a ±2-week window. A series of questionnaires will also be administered before and after training. All participants will complete a semi-structured exit interview to provide feedback on their experience of participating in ADIE Therapy. Participants who complete the study will be invited to take part in an optional three-month follow-up assessment (Week 18), which repeats the same interoceptive tasks and questionnaires to evaluate longer-term effects of the therapy.

The present study is an open-label, single-arm acceptability and feasibility study. The investigators aim to recruit a total of 20 participants.

Inclusion Criteria:

• 18 years old or older
• Residing in the UK and able to travel into London
• Can read and write in English
• Have had a diagnosis of Primary Breast Cancer
• Have completed active, hospital-based treatment for primary breast cancer (Stages 1, 2 or 3; this refers to radiotherapy, surgery, or chemotherapy) 6 months - 10 years previously (this does not apply to ongoing endocrine (hormone) therapy)

Exclusion Criteria:

• Currently taking medication for cardiac arrhythmia (e.g., beta blockers)
• Currently in active treatment for breast cancer and/or other types of cancer
• Currently pregnant

De-identified IPD will be shared with other researchers to comply with open science practices.

De-identified IPD will be shared on an online, open science data repository platform from the time that the study has been published and will be available indefinitely.

De-identified IPD will be available open access.