The Mediating Role of Quality of Life in the Relationship Between Cancer-Related Fatigue and Mental Distress Among Breast Cancer Survivors

BACKGROUND: Cancer-related fatigue (CRF) is one of the most prevalent and distressing symptoms among women with breast cancer. The symptoms influence psychological outcomes through functional status and quality of life (QoL). However, whether multidimensional QoL domains mediate the relationship between CRF and mental distress remains unclear. OBJECTIVE: To test a parallel multiple mediation model evaluating the effects of CRF on mental distress through physiological, psychological, social, and environmental QoL domains. METHODS: This cross-sectional study recruited 84 patients with breast cancer receiving postoperative adjuvant therapy in southern Taiwan. Participants completed the Brief Fatigue Inventory-Taiwan Form, World Health Organization Quality of Life-BREF, and Brief Symptom Rating Scale-5. Pearson correlations were calculated, and mediation analyses were tested using a parallel mediation model (PROCESS model 4). RESULTS: CRF was positively associated with mental distress and negatively associated with all QoL domains. Although QoL domains were significantly correlated with mental distress at the bivariate level, none demonstrated significant independent mediation effects in the parallel model. The overall model explained 45% of the variance in mental distress. Findings indicate that CRF exerted a predominantly direct effect rather than operating indirectly through perceived QoL domains. CONCLUSION: Contrary to theoretical expectations, multidimensional QoL domains did not function as mechanistic pathways linking CRF to mental distress. IMPLICATIONS FOR ONCOLOGY NURSING PRACTICE: These findings highlight CRF as a proximal psychological stressor. Oncology nurses should prioritize systematic fatigue assessment and targeted fatigue management, as mental distress may not be adequately alleviated by improvements in global QoL alone without directly addressing fatigue.