The Mediating Effects of Self-Esteem and Optimism on the Relationship between Quality of Life and Depressive Symptoms of Breast Cancer Patients

Objective This study investigated the mediating effects of the internal psychological factors of self-esteem and optimism on the relationship between breast cancer patients' quality of life in terms of symptoms and functioning and depressive symptoms. Methods The study centered on 384 breast cancer patients who had within a 24-month period received diagnosis of 0-4 stage cancer and had medical treatment. To achieve the study's purpose, the study made use of EORTC QLQ BR23, CES-D, and the Self-Esteem and Optimism Scales. Results Findings revealed that breast cancer patients' quality of life was negatively impacted by self-esteem and optimism, and that self-esteem and optimism impacted negatively on depressive symptoms. Analyses showed that when breast cancer patients' quality of life affects depressive symptoms, the full mediation effect of self-esteem was statistically significant. Also, findings revealed there to be a significant partial mediation effect due to optimism. Conclusion Study findings demonstrated that enhancing self-esteem is crucial in the psychological intervention of depressive symptoms because self-esteem functioned as the main causal factor accounting for all variation when breast cancer patients' quality of life affected depressive symptoms. In addition, results suggested that optimism is also vital to psychological intervention because it functioned as partial cause of heightened depressive symptoms when breast cancer patients' quality of life affected depressive symptoms.