Abstract
Background: Seventy-five percent of breast cancers are hormone receptor positive meaning hormone therapy is prescribed for up to 10 years to reduce the risk of recurrence. In addition to the general physical and psychological survivorship issues including experiencing distress that cancer patients need to manage, hormone therapy itself has side effects, and this burden is often correlated with distress. However, the symptom-distress relationship is not well understood, and they are often treated separately without acknowledgement of the potential interaction. Theoretical models provide potential frameworks for understanding distress in physical illness and give an indication for the variables that may be associated with the symptom-distress relationship. Evidence for two models, the common- sense model of illness representations (CSM) and acceptance and commitment therapy (ACT), is varied in cancer. There are several reviews of the CSM illness perceptions providing an indication of the beliefs and cognitions about illness in understanding distress in cancer which may contribute to intervention development. Despite no systematic review of ACT processes and distress in cancer, ACT interventions are common after a cancer diagnosis. ACT proposes that inflexible processes such as experiential avoidance and cognitive fusion may lead to distress, whilst interventions aim to increase psychologically flexible skills such as acceptance and present moment awareness to encourage meaningful, values-driven behaviour. Longitudinal data for both models in cancer is scarce, particularly in this population, limiting the conclusions that can be drawn regarding their contribution to explaining distress. Understanding these models and variables will provide targets for future interventions to better manage the symptoms and distress experienced by these women.Aims and objectives: The primary aim of the PhD was to determine the relationship between psychosocial factors including cognitive behavioural and acceptance and commitment therapy (ACT) processes and symptom experience and distress in female breast cancer survivors on adjuvant hormone therapy. A pragmatic multi-methods approach was used to provide a thorough understanding of symptoms and distress, drawing on the strengths of both qualitative and quantitative methodology. The PhD objectives were to:
- conduct a systematic review and meta-analysis of the association of ACT processes with distress in people with cancer.
- conduct a qualitative study to explore symptoms and distress to understand the emotional impact of taking hormone therapy in breast cancer survivors.
- conduct a longitudinal observational study to understand the psychosocial correlates of symptoms and distress, and the potential mediators and moderators of the symptom-distress relationship for breast cancer survivors on hormone therapy.
Methods: A systematic review and meta-analysis (Chapter 4, paper published in Health Psychology Review, 2023) was conducted to identify the strength and direction of relationships between ACT processes and distress across all cancer groups. For the qualitative study (Chapter 5), semi-structured interviews were conducted with breast cancer survivors on hormone therapy to explore distress and experience of symptoms. Finally, a longitudinal observational study (Chapters 6 and 7) tested psychological variables, including ACT processes and CSM illness perceptions, to predict distress and tested hypothesised third variables in the symptom-distress pathway as mediators and moderators.
Results: For the systematic review, 108 studies were included, with 77 meta-analysed. Flexible processes were associated with lower distress whilst inflexible processes were associated with higher distress. This comprehensive review supports elements of ACT being associated with distress in the context of cancer, highlighting potential key processes for further investigation. For the qualitative study, an inductive reflexive thematic analysis of 23 patient interviews generated themes around why symptoms are distressing for breast cancer survivors on hormone therapy. Themes focused on helplessness around symptoms, living with and managing difficult feelings around loss and change, living with fear, worry and uncertainty around side effects and the internal conflict when making treatment decisions which goes beyond previous research which focuses on adherence to this medication. This study identifies specific areas to target in clinical communication as well as content for intervention development; including providing clearer information about side effect expectations, helping manage the helplessness around symptoms and supporting the acceptance of the loss and change associated with the impact of side effects. The longitudinal observational study recruited 269 breast cancer survivors in the first 2 years of taking hormone therapy with a 90% retention rate at 6 months and 83% at 12 months. ACT processes explained a greater amount of variance in distress in this population than the CSM illness perceptions, although an integrated model consisting of several cognitive- behavioural processes across models predicted more variance in 12-month distress than any model alone. Several psychological processes including cognitive fusion, values obstruction, symptom focusing, breast cancer consequences and embarrassment avoidance mediated the symptom-distress pathway, indicating that an increase in symptom burden at baseline resulted in a change in the psychological process at 6 months which in turn, resulted in increased distress at 12 months. Treatment coherence and damage beliefs moderated the symptom-distress pathway whereby those who displayed greater understanding of their treatment had less impact of symptoms on distress and those who felt that symptom indicated damage to the body had a larger impact on distress.
Conclusions: This PhD has contributed to understanding distress and symptom burden in breast cancer survivors on hormone therapy whilst understanding why symptoms might be distressing as well as how and for whom symptoms may lead to distress. ACT is a useful model for understanding distress in this population and interventions should be developed from the evidence base. Additionally, an integrated model may be more useful to understand distress in this population as variables from several cognitive-behavioural models were identified as significant mediators and moderators in the symptom-distress pathway. These findings provide targets for interventions that may help mitigate the negative impact of symptoms on these women. This PhD has the potential to inform clinical practice and intervention development and ultimately improve outcomes for this population.
| Date of Award | 1 Jul 2024 |
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| Original language | English |
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| Supervisor | Lyndsay Hughes (Supervisor) & Rona Moss-Morris (Supervisor) |