Acceptance and Commitment Therapy for Individuals With Head and Neck Cancer Experiencing Psychological Distress: A Hermeneutic Single-Case Efficacy Design

This study aims contribute to the theoretical literature on acceptance and commitment therapy (ACT) as well as the processes of psychological change for patients with head and neck cancer (HNC). Unlike some other cancer sites, the physical and emotional impact of living with HNC can be detrimental to the fundamental aspects of an individual's life (such as breathing, eating, hearing), and also cause significant changes to physical appearance. This forms the basis for specialised research of HNC patients. There is a tendency within the current cancer literature towards researching and understanding and other types of cancer or grouping HNC patients into heterogeneous cancer samples, leaving an evident gap of knowledge. Studies that have assessed the effectiveness of ACT mirror this trend, using either breast cancer or heterogeneous cancer samples.

Employing a single-case method with both quantitative and qualitative components will give a more precise understanding of the processes within ACT that are helpful and most importantly, why. This may have direct implications for informing the on-going practice of professionals working therapeutically using ACT, enabling them to refine interventions and focal principles. In support of this, a recent review of ACT interventions concluded that although efficacy of ACT is probable, there is a lack of knowledge of how it works. Single-case research is a pragmatic first step in exploring the efficacy of ACT for HNC patients and increasing understanding of the potential mechanisms of change. A Hermeneutic Single Case Efficacy Design for three participants will be used. This is a legalistic single case study method which allows the assessment of intervention effects in single therapy cases within a naturalistic clinical context. It uses a mixture of qualitative(change interview) and quantitative methods (questionnaires) to create a set of evidence that allows detection of causal links between therapy process and outcome.

In order to minimise the risk of coercion, a member of the patients care team (Clinical Psychologist) will be the first point of contact for potential participants, introducing waiting-list patients to the research and giving them the information sheet if they verbally indicate interest. After reading the information sheet, if they verbally agree to continue with the research, they will be put into contact with the researcher who will answer any additional questions, ensuring that the person has sufficient time to consider participating or not. Written informed consent will be collected from each participant before they undergo any intervention related to the study. One copy of this will be kept by the participant, one will be kept by the researcher, and a third will be retained in the patient's hospital records.

Informed consent will be gained in accordance with the Research Ethics Committee (REC) guidance, and Good Clinical Practice (GCP) and any other regulatory requirements that might be introduced. The researcher and the participant will both sign and date the informed consent form before the person can participate in the study. The researcher will emphasise to them that consent regarding study participation is entirely voluntary and may be withdrawn at any time without penalty or affecting their care. For example, if the patient withdraws from the study, they will return to the point of the psychological therapy waiting list that they were taken from, therefore not affecting the length of time they have to wait to see a therapist. There will be no monetary incentive to take part in the research, reducing the risk of coercion.

This research aims to use a sample most representative of individuals in clinical practice, therefore site and stage of HNC does not feature the inclusion criteria. The GAD-7 (generalised anxiety disorder) and PHQ-9 (patient health: depression) questionnaires will be used using 'caseness' thresholds for anxiety and/or depression as these are widely used and the current screening method for most psychology therapy services.