Cancer-related fatigue in breast cancer survivors: more evidence for a physiological substrate

Abstract

Background: Cancer-related fatigue (CRF) is a complex multi-dimensional construct related to reduced physical function and health-related quality of life. This symptom is under-reported by patients and and undertreated by clinicians. Recent reviews have concluded that exercise reduces cancer-related fatigue. The NCCN recommends that all cancer patients should be screened for fatigue regularly. As management of CRF is currently suboptimal, a change of approach is required. Method(s): Breast cancer survivors who had finished their treatments in the last 6 months, did not have any evidence of disease and were able to manage the accelerometer were offered to participate in a cross sectional study. CRF was evaluated through PERFORM, a questionnaire developed and validated in Spanish speakers. Weekly moderate-vigorous physical activity (WMVA) was objectively evaluated with accelerometers. Physical condition was evaluated through the one mile-walk test, hand-held dynamometer and sit to stand test. Result(s): 96 women with a history of breast cancer were recruited between March -2014 and April-2016. Age 52 (29-78), BMI 26 (18-41), waist 86 cm (65-116). 72% had received anthracyclines, 17% Herceptin, 70% radiotherapy. Basal heart rate 74 bpm (56-102); Final heart rate (after walking one mile) 107 bpm (68-159); Estimated VO2max 27,7 ml/kg/min (7,7-47); Strength right upper extremity was 26 Kg (10-40). Sit to stand test 7,4 (4,1-18,4) s. WMVPA was 231 min (69,5-424,5). Median PERFORM score was 46 (12-60). There were not any significant correlations for previous treatments, physical condition, anthropometry or physical activity with fatigue score. Heart rate (both basal and final) were significantly associated to fatigue (p < 0.05). Conclusion(s): Despite of meeting international recommendations for physical activity, this sample exhibited a poor cardiorespiratory fitness and cardiometabolic profile. Basal and post exercise heart rate were the only predictors of fatigue in our series. Neither previous treatments nor physical condition or adiposity signs had a definitive relationship with fatigue. Other authors have suggested that fatigue is associated with a maladaptive autonomic profile. Further research studying heart rate variability is warranted.