Craig Gouldthorpe, Andrew Davies
INTRODUCTION AND AIMS: Circadian rest-activity rhythms describe patterns in rest and physical activity across and between 24-hour periods. Research highlights important associations between circadian disruption, including the rest-activity rhythm, and clinical outcomes in patients with cancer. This study aimed to assess the circadian rest-activity rhythms, and prevalence of circadian rest-activity rhythm disorders (CARDs), in patients with advanced cancer. METHODS: An observational study of 72 outpatients with locally advanced or metastatic cancer took place over a 1-year period, considering objective (accelerometry) and subjective (patient diary) measures of circadian rest-activity rhythms, patient-reported outcomes (Memorial Symptom Assessment Scale-Short Form, European Organisation for Research and Treatment of Cancer Core Quality of Life Questionnaire, brief Pittsburgh Sleep Quality Index and Epworth Sleepiness Scale) and clinical markers. RESULTS: CARDs affected up to 60% of patients with advanced cancer. Increased circadian disruption was seen in patients with more advanced disease, particularly with metastatic organ involvement (p=0.038), poorer performance status (p=0.018), higher inflammatory status (p=0.018), anaemia (p=0.007) and iron deficiency (p=0.002). The study also highlights that patients with advanced cancer and a CARD diagnosis have a higher symptom burden, particularly fatigue (p=0.003) and drowsiness (p=0.005), higher symptom-related distress (p<0.001), a poorer Global Health tatus (p=0.005) and poorer functioning subscales (p<0.014). CONCLUSION: This is the first study to assess circadian rest-activity rhythms in accordance with new assessment and diagnostic guidelines. Further research is now required to validate the diagnostic criteria, standardise technical approaches to assessment and consider risk factors for the development of a CARD and additional clinical outcomes of interest.