A mixed-methods investigation of the influence of poor sleep on adherence to adjuvant hormonal therapy in breast cancer survivors

Following breast cancer treatment, women with hormone positive breast cancer are prescribed hormone therapy for 5-10 years to reduce the risk of breast cancer recurrence. However, around 50% of women prescribed hormone therapy do not take to their prescription as instructed. This represents waste of NHS resources, and increases the risks of cancer recurrence. Often, non-adherence to hormone therapy is related to the significant side effects, one of the most common being disturbed sleep. However, there is a lack of research considering the influence of sleep and other specific side effects on adherence to this treatment, as research tends to group all side effects together. This project aims to address this by conducting: i) a survey-based study investigating the impact of sleep and other side effects on adherence, ii) a pilot intervention study to evaluate the effect of improving sleep on adherence to hormone therapy, and the feasibility of this intervention, iii) a qualitative study to explore the experience of this intervention and its acceptability and feasibility.

Study 1) Cross-sectional questionnaire- based study exploring the predictive value of poor sleep and other common side effects on non-adherence to hormone therapy in breast cancer survivors. Cross-sectional data will be obtained using self-reported questionnaires.
We will explore the relationship between measures of sleep and other side effects and adherence, then explore the extent to which each individual side effect predicts adherence independently. The relationship between self-report measures of sleep and other side effects will be investigated to identify which variables predict adherence.
The study will aim to recruit a large, representative sample (Scottish women aged 18 or over, prescribed adjuvant hormone therapy for primary breast cancer). We will aim to recruit around 400 breast cancer survivors currently prescribed HT. Recruitment will involve liaising with organisations such as Beatson Oncology Centre, Maggie's Centre, and Cancer Support Scotland to facilitate meeting this target.

Study 2a) Exploration of the acceptability, feasibility and preliminary effectiveness of CBT-I for poor sleep on improving sleep on adherence to hormone therapy
We will explore the feasibility and acceptability and effectiveness of delivering an intervention for sleep in a population of BCS who are self-reported to be non-adherent to hormone therapy.
Participants will be randomly allocated on a 2:1 basis to an intervention group (60 participants) or waitlist control group (30 participants). The intervention group will receive 3 weekly one-hour sessions of Cognitive-Behavioural Therapy (CBT). The study will use a mixed-methods, repeated measures design for assessment of the effectiveness of the intervention (on improving both sleep and adherence) (questionnaires used across 3 assessment points), feasibility of delivering this intervention, the experience and acceptability of the intervention.

Study 2b) Qualitative exploration of the acceptability and feasibility of implementing an intervention for sleep to improve adherence
Qualitative interview methodology will be used to assess the experience of taking part in the sleep intervention, and to determine any areas of refinement that would enhance the materials or their delivery (acceptability and feasibility). We will aim to recruit 40 participants (female, aged 18 years or older, prescribed adjuvant hormone therapy for primary breast cancer), although recruitment may cease before this point if data saturation is reached. Data will be analysed using thematic analysis.