One-day Mind Programme for Women With Breast Cancer: A Pilot Study on the Acceptability and Effectiveness of a Brief ACT and Compassion-based Intervention on Breast Cancer-specific Outcomes

Breast cancer (BC) remains the second most common type of cancer worldwide and the leading cancer affecting women. In Portugal there are approximately 7000 new diagnoses of BC each year. The diagnosis and treatment of BC can profoundly impact patients' physical (e.g., fatigue, pain) and psychological (e.g. distress, depressive symptoms) well-being. Psychological interventions that foster adjustment to cancer (and to its treatment), mental health and quality of life are therefore essential.

The use of contextual behavioural therapies in samples of people with chronic diseases has shown evidence of efficacy in improving psychopathological symptoms. Additionally, a recent meta-analysis concluded that the use of single-session ACT interventions in samples with chronically ill patients may be more viable, acceptable, and beneficial compared to multiple-session ACT interventions.

This interventional study aims to test the acceptability (aim 1) and effectiveness (aim 2) of a brief (7-hour) version of the "Mind Programme for Women with Breast Cancer", which is providing promising efficacy results. Similarly to the original programme, this brief version integrates contextual behavioural therapies (Acceptance and Commitment Therapy - ACT, and Compassion-Focused Therapy - CFT), is tailored to BC women and presents a group and online format, delivered by two psychologists. This trial also aims to determine the contribution of mediating (psychological flexibility, self-compassion) and moderating (e.g. age) factors in treatment effectiveness (aim 3).

Women with BC who had previously shown interest in participating in the RCT of the (original) multiple-session Mind Programme, but that were either not eligible or were allocated to the waiting list, will be invited to join this trial. Participants will complete the 7-h intervention "One-day Mind Programme for women with breast cancer" and complete self-reported outcome measures (e.g. EORTC QLQ-C30, HADS, CompACT, SCS, resource use questionnaire) in three different timepoints (pre, post, and 3-month follow-up). The G*Power 3.1.9.7 software was used to calculate the sample size (N=36) required for a single-armed linear repeated-measures model with three measurements and assuming a comparable (medium) effect size to that estimated in similar studies, an alpha of 0.05 and a minimum of 90% power.

High levels of acceptability and improvements in outcomes (e.g. breast cancer-specific quality of life, anxiety and depressive symptoms, psychological flexibility, self-compassion, health-related costs) are expected at post-treatment and follow-up. This trial seeks to contribute to the integration of brief and cost-effective psychosocial interventions in the usual healthcare for BC patients and survivors.