The role of fatigue and sleep quality in the link between pain severity, perceived injustice and pain catastrophizing in breast cancer survivors with pain: a network analysis.

PURPOSE: Breast cancer survivors frequently report persistent pain accompanied by fatigue, sleep disturbances, and psychological factors such as pain catastrophizing and perceived injustice. Although these symptoms often co-occur, their multivariate interrelations and potential directional dependencies remain insufficiently understood. This study investigates the relationship between pain severity, perceived injustice and pain catastrophizing, and their connection with fatigue and sleep quality in breast cancer survivors by examining the interconnections, strengths, and directional dependencies of these symptoms. METHODS: This cross-sectional is a secondary analysis of baseline data of 2 randomized controlled trials of 278 breast cancer survivors with pain. Pain severity, pain catastrophizing, perceived injustice, fatigue, and sleep-related symptoms were assessed using validated questionnaires. Partial correlations between the outcomes are examined by a regularized Gaussian Graphical Model (GGM), while a Directed Acyclic Graph (DAG) explored the directional probabilities. RESULTS: Fatigue and sleep-related symptoms, rather than pain severity, occupy central positions in the symptom network of breast cancer survivors with pain. Fatigue appears to be a key linking mechanism between perceived injustice and sleep, while pain catastrophizing is primarily associated with perceived injustice unfairness. Pain severity showed no directionality within the network. CONCLUSIONS: Fatigue links sleep problems to perceived injustice in breast cancer survivors with pain, highlighting perceived injustice as a key target for interventions beyond pain severity.