Abstract / Summary
Young and middle-aged patients with breast cancer receiving particle therapy commonly experience elevated Fear of Progression (FoP). Evidence for the effectiveness of acceptance and commitment therapy (ACT) in this population remains limited. This study evaluated the effects of ACT on FoP and on related psychological outcomes, namely psychological flexibility and psychological distress. This parallel-group randomized controlled trial was conducted at an oncology hospital in Shanghai, China, and enrolled participants between June and August 2025. A total of 108 young and middle-aged patients with breast cancer and elevated FoP (Fear of Progression Questionnaire-Short Form, FoP-Q-SF, ≥34) were randomly assigned in a 1:1 ratio to the intervention group (n = 54) or control group (n = 54). The intervention group received five group-based sessions (90-120 min each) over 2.5 weeks, covering acceptance, cognitive defusion, present-moment awareness, self-as-context, values clarification, and committed action, whereas the control group received usual care. Outcomes were assessed at baseline, immediately after the intervention, and at 1- and 3-month follow-ups. Intention-to-treat analyses used generalized estimating equations adjusted for cancer stage, age, and education. Sensitivity analyses used multiple imputation. The overall attrition was 12%, and no intervention-related adverse events were identified. Compared with the control group, the intervention group showed greater reductions in FoP at all post-intervention time points (T1-T3, all p < 0.001) and in psychological distress at all follow-ups (T1-T3, all p < 0.05). These findings were robust in sensitivity analyses. The effect on psychological flexibility emerged later, reaching statistical significance at T3 (p = 0.037) and remaining significant in the sensitivity analysis (p = 0.046). Acceptance and commitment therapy reduced FoP and psychological distress in this population, with a delayed effect on psychological flexibility. These findings support integrating structured, group-based ACT into routine care during particle therapy. Multicenter trials with longer follow-up are needed. Chinese Clinical Trial Registry Identifier: ChiCTR2500104142.