Abstract 7356: Feasibility, acceptability, and preliminary efficacy of acceptance and commitment therapy in women living with metastatic breast cancer

Abstract Purpose: While metastatic breast cancer (BC) has no cure, treatment advances are helping women live longer. However, these women often experience debilitating treatment symptoms and emotional distress. Acceptance and commitment therapy (ACT) is an evidence-based intervention that improves mood and quality of life while allowing for the feelings of grief and loss that are expected when facing a life-limiting prognosis. There is a paucity of randomized controlled trials of ACT among women with metastatic BC. This study examined acceptability, feasibility, and preliminary efficacy of a tailored ACT intervention in a randomized pilot trial. Procedures: Women with stage IV BC (N=30) were randomized 1:1:1 to ACT, usual care, or Cognitive and Behavioral Stress Management (CBSM). ACT and CBSM included 8 weekly group sessions (90 minutes each) delivered via videoconference. Participants completed FACT-B and PROMIS measures at baseline, mid-intervention, post-intervention and 1-month follow-up. Cohen’s D effect sizes were calculated. Results: On average, women were 59.7 years old and 5.6 years from metastatic BC diagnosis. Enrollment rate was 88.5% (31/35), randomization rate was 96.8% (30/31), and retention rate was 90% (9/10 for ACT, 9/10 for usual care, 9/10 for CBSM). 100% of women in both ACT and CBSM attended at least half of the 8 sessions and 88.8% attended at least 6 sessions. 94.4% of women in ACT and 88.2% in CBSM would recommend the intervention to another woman living with metastatic BC. The effect sizes at post intervention were greater than .8 for ACT vs. usual care, while only anxiety and meaning were greater than .8 in CBSM vs. usual care (Table 1). Conclusion: Findings demonstrate high feasibility and acceptability for ACT and CBSM in metastatic BC. A full-scale randomized control trial is needed to determine the stability of effects and whether ACT has robust effects on outcomes of interest and optimizes HRQoL among women with metastatic BC. Citation Format: Ashley Hatch, Joanna B. Torzewski, Jessica L. Thomas, Heidy N. Medina, Fiona S. Horner, William J. Gradishar, David Victorson, Frank J. Penedo, Michael H. Antoni, Patricia I. Moreno. Feasibility, acceptability, and preliminary efficacy of acceptance and commitment therapy in women living with metastatic breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 7356.