Abstract
PURPOSE: Physical activity research among patients with metastatic breast cancer (MBC) is limited. This study examined the feasibility and potential benefits of Fit2ThriveMB, a tailored mHealth intervention. METHODS: Insufficiently active individuals with MBC (n = 49) were randomized 1:1 to Fit2ThriveMB (Fit2ThriveMB app, Fitbit, and weekly coaching calls) or Healthy Lifestyle attention control (Cancer.Net app and weekly calls) for 12 weeks. Fit2ThriveMB aimed to increase daily steps via an algorithm tailored to daily symptom rating and step goal attainment. The primary outcome was feasibility defined as ≥ 80% completion rate. Secondary feasibility metrics included meeting daily step goal and wearing the Fitbit ≥ 70% of study days, fidelity, adherence to intervention features and safety. Secondary outcomes included physical activity, sedentary time, patient reported outcomes (PROs), health-related quality of life (QOL) and social cognitive theory constructs. A subsample (n = 25) completed functional performance tests via video conferencing. RESULTS: The completion rate was 98% (n = 1 died). No related adverse events were reported. Fit2ThriveMB participants (n = 24) wore the Fitbit 92.7%, met their step goal 53.1%, set a step goal 84.6% and used the app 94.1% of 84 study days. Intent-to-treat analyses indicated trends toward improvements in activity, QOL, and some PROs, social cognitive theory constructs, and functional performance tests favoring the Fit2ThriveMB group. Significant effects favoring Fit2ThriveMB were observed for self-efficacy and goal-setting. However, some PROs and functional performance improvements favored the control group (p-values > 0.05). CONCLUSIONS: Fit2ThriveMB is feasible and safe for patients with MBC and warrants further evaluation in randomized controlled trials with larger sample sizes. Registration Clinicaltrials.gov NCT04129346, https://clinicaltrials.gov/ct2/show/NCT04129346.