The primary aim of this randomized controlled trial is to evaluate the effect of ConquerFear-Group (CF-G), compared with a control condition (CC), on Fear of Cancer Recurrence (FCR). Secondary aims are to explore the effect of CF-G on emotion regulation and additional psychological outcomes, and to explore mediating effects of emotion regulation, metacognitions, working alliance, patient adherence, and group cohesion. In addition, treatment expectancy, participation in other treatments after completion of the intervention of the study and demographic and clinical variables will be explored as moderators.

A randomized controlled trial testing the efficacy of ConquerFear-Group (CF-G) on breast cancer survivors with clinical levels of Fear of Cancer Recurrence (FCR), compared with a control condition (CC), will be conducted.

The aims are to:

1. Evaluate the efficacy of CF-G on FCR,
2. Explore the effects on the secondary outcomes of emotion regulation, general distress, health-related QoL, survivors' unmet needs, mindfulness, metacognitions, intervention satisfaction, negative effects of intervention, and sleep.
3. Explore emotion regulation, metacognitions, working alliance, patient adherence, and group cohesion will be explored as possible mediators.*
4. Explore treatment expectancy, participation in other treatments after completion of the CF-G or the CC and demographic and clinical variables as possible moderators.

Primary hypothesis:

CF-G will yield larger reductions in FCR than CC at post treatment, and the effect will be maintained through the follow-up period.

Secondary hypotheses:

CF-G will demonstrate a larger improvement in measures of emotion regulation than CC following the intervention period.

Changes in emotion regulation during treatment will mediate the effect of CF-G on FCR.* Changes in metacognitions during treatment will mediate the effect of CF-G on FCR.* CF-G will yield larger reductions in general distress, health-related QoL, survivors' unmet needs than CC, and CF-G will yield larger improvements in metacognitions, mindfulness, and sleep than CC following the intervention period.

*The prerequesties for conducting for mediation analysis were not fulfilled. Consequently, these analyses were abandoned. Data can be obtained upon request.

Inclusion Criteria:

1. Eligible patients have a confirmed past diagnosis of stage 1-3 breast cancer,
2. have been treated with curative intent,
3. have completed all hospital-based adjuvant treatments 3 months to 5 years prior to study entry,
4. are disease free,
5. scores in the clinical range (≥22) on the Short Form of the Fear of Cancer Recurrence Inventory (FCRI-SF),
6. are able to read and write Danish,
7. are over the age of 18 years, and
8. are able to give informed consent.

Exclusion Criteria:

1. self-reported current major depression,
2. currently receiving psychological treatment from a therapist not involved in the study,
3. self-reported active psychotic illness or other severe psychiatric conditions.

All data underlying publication will be shared in accordance with current data sharing regulations at host institutions.

6 months after publication

Researchers aiming to publish IPD meta-analyses. The authors to review requests are the PI and senior supervisors (NT, MSO, RZ, PB).

The investigator and assessor is masked in terms of not knowing to which condition the participants will be randomized until after completion of the baseline assessment. The participants are masked in terms of not knowing that one intervention is hypothesized to yield larger effects than the other.