KMAN Publication Inc. (KMANPUB) Psychology of Woman Journal 3041-8615 In Press 2027 05 01 Comparison of the Effectiveness of Mindfulness-Based Cognitive Therapy and Acceptance and Commitment Therapy on Ideas of Reference, Thought–Action Fusion, and Cognitive Avoidance in Women with Breast Cancer Comparison of the Effectiveness of Mindfulness-Based Cognitive Therapy and Acceptance and Commitment Therapy on Ideas of Reference, Thought–Action Fusion, and Cognitive Avoidance in Women with Breast Cancer 1 15 EN Journal Article 2026 05 18 <p><strong>Objective:</strong> The present study aimed to compare the effectiveness of mindfulness-based cognitive therapy (MBCT) and acceptance and commitment therapy (ACT) in reducing ideas of reference, thought–action fusion, and cognitive avoidance among women with breast cancer.</p> <p><strong>Methods and Materials: </strong>This study employed a quasi-experimental pretest–posttest design. The statistical population consisted of all women with breast cancer who attended a radiotherapy and oncology center in Tehran between September 23, 2025, and March 20, 2026. Accordingly, 45 participants were selected and randomly assigned to three groups. The first experimental group received the mindfulness-based cognitive therapy protocol developed by Segal, Williams, and Teasdale (2013) over eight sessions, while the second experimental group received eight sessions of acceptance and commitment therapy (ACT) based on the protocol developed by Dahl et al. (2014). The control group received no intervention. The research instruments included the Ideas of Reference Questionnaire (Ehring, 1990), the Thought–Action Fusion Questionnaire (Shafran, Thordarson, &amp; Rachman, 1996), and the Cognitive Avoidance Questionnaire (Sexton &amp; Dugas, 2009). The data were analyzed using multivariate analysis of variance (MANOVA).</p> <p><strong>Findings:</strong> Based on the mean posttest scores of the experimental groups, the findings indicated that both mindfulness-based cognitive therapy and acceptance and commitment therapy were effective in reducing ideas of reference, thought–action fusion, and cognitive avoidance among women with breast cancer.</p> <p><strong>Conclusion:</strong> It can be concluded that both mindfulness-based cognitive therapy and acceptance and commitment therapy were effective in improving the dependent variables among women with breast cancer.</p> https://journals.kmanpub.com/index.php/psywoman/article/download/5941/11387