The PAPHIO study protocol: a randomised controlled trial with a 2 x 2 crossover design of physical activity adherence, psychological health and immunological outcomes in breast cancer survivors

BACKGROUND: The PAPHIO study; a randomized controlled trial with 2X2 crossover design will implement a self-directed physical activity program in which participants will engage in self-monitoring and receive motivational interviewing to enhance physical activity adherence. The study aims to determine the effects of 24 weeks self-directed activity combined with motivational interviewing (MI) on (i) psychological health, (ii) quality of life (QoL) and (iii) immune function in female breast cancer survivors. METHODS: The study will recruit 64 female breast cancer survivors within 3 years of diagnosis and at least 6 months post primary treatments at Western Health Sunshine Hospital, Melbourne, Australia. They will be randomly allocated to immediate intervention (IIG group) or delayed intervention groups (DIG group) in a 1:1 ratio. All participants will be given a wearable device (Fitbit Alta HR) and undertake self-directed physical activity for 24 weeks and will receive MI for 12 weeks (IIG; during week 0 to week 12 and DIG; during week 13 to week 24). Participants' daily step count and the changes of immune cell functionality will be assessed at the beginning (week 1: T1), week 12 (T2) and week 24 (T3) of the program. Physical activity adherence will be assessed at T2 and T3. Participants will also complete four questionnaires assessing exercise self-regulation (BREQ2), exercise barrier and task self-efficacy, mental health (DASS-21) and QoL (FACT-B) at three time points (T1 to T3). Linear-mixed models will be used to assess the relationship between physical activity volume by step counting and mental health (DASS-21), QoL (FACT-B), immune biomarkers, self-regulation (BREQ2) and self-efficacy at T1, T2 and T3;between 2 groups. DISCUSSION: We expect this physical activity intervention to be acceptable and beneficial to the participants in terms of psychological and immunological well-being with the potential outcomes to be implemented more widely at relatively low cost to these or other patient populations. TRIAL REGISTRATION: Australian New Zealand Clinical trials Registry- ACTRN12619001271190. Prospectively registered on 13 September 2019.