Feasibility, acceptability, and effectiveness of an asynchronous, internet-delivered acceptance and commitment therapy for people living with cancer: A pilot randomized controlled trial using mixed methods

People living with cancer often experience significant psychological distress, yet accessible and scalable psychological interventions remain limited. To address this gap, the present study aimed to examine the feasibility, acceptability, and preliminary effectiveness of an asynchronous, self-guided, internet-delivered Acceptance and Commitment Therapy (ACT) intervention for adults living with cancer at different cancer stages and treatment phases. In this mixed-methods pilot randomized controlled trial, sixty eligible participants were randomly assigned to either an intervention group or a wait-list control group. The two-week program comprised eight 30-minute modules designed to engage participants with the six core therapeutic processes of ACT. Measures of psychological distress, anxiety, and depression were administered at baseline, midpoint, and post-intervention. Semi-structured interviews were also conducted to gain deeper insights into participants’ experiences. Quantitative data were analyzed using analysis of variance (ANOVA), and qualitative data were examined through thematic analysis. Results showed significant reductions in psychological distress and anxiety, with marginal improvement in depression compared to the control group. A 70 % retention rate and 63 % completion rate indicated acceptable feasibility, and participants reported moderate satisfaction with the intervention. Qualitative interviews revealed four key domains: accessibility and feasibility, therapeutic experience and acceptability, perceived benefits, and implementation challenges and recommendations. These findings highlight the potential of asynchronous, self-guided, internet-delivered ACT as an adjunctive psychological intervention in oncology care, particularly for individuals with limited access to in-person psychotherapy. Future iterations may benefit from optimizing intervention dosage and difficulty, incorporating interactive elements and diverse delivery formats, and integrating individualized feedback to enhance participant engagement and overall effectiveness.