The Mistletoe and Breast Cancer (MAB) Study: A UK Mixed-Phase, Pilot, Placebo-Controlled, Double-Blind, Randomised...

To test the feasibility of a mixed-phase, pilot, placebo-controlled, double-blind trial of mistletoe therapy (MT) with an embedded qualitative study in the UK National Health Service (NHS) setting.

The aim was to recruit 45 patients via an NHS oncology centre with a diagnosis of early or locally advanced breast cancer. Participants were allocated to Iscador^® Malus, Iscador^® Pinus, or physiological saline (placebo). Diaries and quality-of-life questionnaires were administered. Qualitative interviews were conducted with participants, oncologists, and nurses. Feasibility was assessed by recruitment, retention, adherence, blinding, and safety.

Sixty-seven patients were approached between August 2019 and March 2020, 15 gave consent, 14 participants were randomised, and 2 withdrew during the trial. Ten participants and five staff were interviewed. Barriers to recruitment were the additional treatments/time, extra injections, and the possibility of placebo allocation. Adherence was very good whilst the participants were on the study therapy. Diaries and interviews indicated that 11/14 participants struggled with injections and skin reactions. There were 22 adverse events due to the MT, related to the injections or skin reactions.

This pilot study examined the feasibility of conducting a randomised placebo-controlled, double-blind trial of mistletoe therapy for breast cancer patients within the UK NHS. The results describe the challenges and achievements of recruitment, retention, adherence, blinding, and safety in this context.