The Illness Representations–Physical Well-Being Interplay Over Time in Breast Cancer Patients

Objective: Many studies have shown the prospective relation of illness representations to breast cancer patients’ well-being. Still, very few have examined their bidirectional relationship over time. Here, the long-term mutual effects between physical well-being and illness representations were examined at the within-person level. Method: Female patients with breast cancer were enrolled in the study 2–5 weeks after the surgery or biopsy (baseline N = 706; M_age = 54.93). Several illness representations (i.e., illness consequences, timeline, personal control, and emotional representations) and physical well-being (i.e., general physical functioning and specific breast and arm symptoms) were assessed at 6, 12, and 18 months after patients’ inclusion in the study (years of data collection: 2019–2021). Two random-intercept cross-lagged panel models were used to examine whether intrapersonal changes in the two variables predicted each other across time. Results: The findings showed strong general relations between illness representations and physical well-being at the between-person level. However, only changes in timeline and emotional representations predicted intrapersonal subsequent changes in physical functioning and arm and breast symptoms, respectively. No other cross-lagged effects were found. Conclusions: While illness representations are significantly associated with physical well-being at the between-person level, their impact significantly varies at the within-person level. The findings reflect the complex relationships between these factors in patients with breast cancer and point to the need for new theoretical approaches to better depict their long-term intrapersonal interplay.