Safety and efficacy of resistance exercise in prostate cancer patients with bone metastases
Background: Due to concerns of fragility fracture, exercise is a perceived contraindication for prostate cancer patients with bone metastases. These patients experience significant functional impairment and muscle atrophy, which may lead to an increased likelihood of skeletal complications (i.e., pathological fracture, bone pain) and/or falls. Safe resistance exercise prescription may counteract this effect. The aim of this feasibility trial was to determine the safety and efficacy of resistance exercise by prostate cancer survivors with bone metastatic disease. Methods: Twenty men with established bone metastases secondary to prostate cancer were randomly assigned to a 12-week resistance exercise program in which exercise prescription was based on the location of bone lesions (n=10) or usual care (n=10). Outcomes included safety and tolerance of the exercise program, physical function, physical activity level, body composition, fatigue, quality of life and psychological distress. Outcomes were compared between groups using analysis of covariance adjusted for baseline values. Results: Participants had significant disease load with 65% of participants presenting with two or more regions affected by bone metastases and an average Gleason score of 8.2±0.9. Five participants (exercise=2; usual care=3) did not complete the intervention, three of which were due to advancing disease (exercise=2; usual care=1). No adverse events or skeletal complications occurred during the supervised exercise sessions. The exercise program was well tolerated as evidenced by high attendance (83%) and compliance rates (93%), and the ability of the participants to exercise at an intensity within the target range for cancer survivors (rating of perceived exertion =13.8±1.5). The change in physical function (muscle strength ~11%; submaximal aerobic exercise capacity ~5% and ambulation ~12%), physical activity level (~24%) and lean mass (~3%) differed significantly between groups following the intervention, with favorable changes in the exercise group compared with the usual care group. No significant between-group differences were observed for fatigue, quality of life or psychological distress. Conclusions: This initial evidence involving a small sample size suggests that appropriately designed and supervised resistance exercise may be safe and well tolerated by prostate cancer patients with bone metastatic disease and can lead to improvements in physical function, physical activity levels and lean mass. Future trials involving larger sample sizes are required to expand these preliminary findings.