Muscle endurance, cancer‐related fatigue, and radiotherapy in prostate cancer survivors

INTRODUCTION: In this study we investigated muscle and cancer-related fatigue (CRF) in prostate cancer survivors (CS) undergoing radiotherapy (RT). METHODS: In 13 CS and 12 controls, CRF was assessed by the Piper Fatigue Scale (PFS), Epworth Sleepiness Scale--Depression subscale (CES-D), physical activity (accelerometer), and hemoglobin levels (Hb). Muscle measures included strength, activation, contractile properties, and endurance during intermittent dorsiflexion. Testing occurred before and after 6 weeks of RT in CS. RESULTS: After RT, the PFS score increased from initial levels in CS only without changes in sleepiness, depression, or physical activity. Hb decreased in CS only [mean (SD): pre, 15 (1.1); post, 14.5 (1.1) g/dl; P = 0.04]. Endurance decreased in CS [mean (SD): pre, 519 (340) s; post, 388 (203) s; P = 0.04] and increased in controls [mean (SD: pre, 616 (387) s; post, 753 (553) s; P = 0.03]. Only endurance was associated with PFS in CS (r = -0.55, P = 0.05). DISCUSSION: Muscle endurance is impaired after RT and may contribute to CRF in CS.