Insomnia in breast cancer: a prospective observational study

STUDY OBJECTIVES: Insomnia in cancer patients is prevalent, persistent and confers risk for physical and psychological disorder. We must better understand how insomnia develops in cancer patients and explore the main contributors to its chronicity so that insomnia management protocols can be integrated more effectively within cancer care. This study monitors the etiology of insomnia in breast cancer patients and identifies risk factors for its persistence. METHODS: 173 females with newly diagnosed, non-metastatic breast cancer were tracked from diagnosis for 12-months. Participants completed monthly sleep assessments using the Insomnia Severity Index (ISI) and 3-monthly health-related quality-of-life assessments using the European Organisation for Research and Treatment of Cancer - Breast (EORTC QLQ-C30-BR23) scale. Clinical data on disease status and treatment regimens were also assessed. RESULTS: Prior to diagnosis, 25% of participants reported sleep disturbance, including 8% with insomnia syndrome (IS). Prevalence increased at cancer diagnosis to 46% (18% IS) and remained stable thereafter at around 50% (21% IS). We also explored sleep status transitions. The most common pattern was to remain a good sleeper (34%-49%) or to persist with insomnia (23%-46%). 77% of good sleepers developed insomnia during the 12-month period and 54% went into insomnia remission. Chemotherapy (odds ratio=0·08, 95% ci 0·02-0·29, p<·001) and pre-diagnosis ISI scores (odds ratio=1·13/unit increase in pre-diagnosis sleep score, 95% ci 1·05-1·21, p=·001) were identified as the main risk factors for persistent insomnia. CONCLUSIONS: These data advance our understanding of insomnia etiology in cancer patients and help identify those who should be prioritised for insomnia management protocols.