Supplementary Material for: ConquerFear-HK: a randomised controlled trial of a metacognition-based, manualised intervention for fear of cancer recurrence among Chinese cancer survivors

Introduction: Fear of cancer recurrence (FCR) is a prominent clinical issue among cancer survivors. This study evaluated the effectiveness of the culturally adapted ConquerFear-HK intervention in reducing FCR among Chinese cancer survivors, compared to standard survivorship care.
Methods: This assessor-masked, two-arm parallel randomised controlled trial, was conducted from June 2021 to February 2024. Cantonese- or Mandarin-speaking Chinese cancer survivors scoring >13 on the Fear of Cancer Recurrence Inventory Short-Form (FCRI-SF) were randomised to either ConquerFear-HK, focusing on attention training, metacognition modification, acceptance, appropriate monitoring behaviour, and goal setting; or to active control providing standardised, multidisciplinary survivorship care. Primary outcome was changes in FCR assessed by FCRI at prior randomisation, immediately post-intervention (T1), 3-month (T2), and 6-month (T3) post-intervention. Intention-to-treat analyses using linear mixed modelling compared outcome changes across timepoints. This trial was registered at ClinicalTrials.gov (NCT04568226).
Results: Of the 175/220 (79.5%) participants recruited, 89 were randomized to ConquerFear-HK and 86 to control. Significant greater FCRI reductions were observed in ConquerFear-HK at T1 (mean difference=-10.66; 95% CI:-20.15, -1.16) and T2 (mean difference=-12.00; 95% CI:-21.90, -2.11), vs. the control (g=0.33-0.36). No significant between-group differences were found at T3.
Conclusion: ConquerFear-HK demonstrates promising short-term (3-month) improvements in FCR among Chinese cancer survivors; however, no sustained benefits were found at 6 months. Possible explanations include the high attrition at 6-month follow-up, a potential early ceiling effect, unconscious therapist bias, or an accelerated adaptation effect in the intervention arm that was achieved later by the control group.