The impact of breast cancer treatments on sleep quality 1 year after cancer diagnosis

Purpose: The increasing number of women living longer with potential side effects of breast cancer treatment highlights the need of a comprehensive assessment of its burden. Therefore, we aimed to quantify the relation between different breast cancer treatments and sleep quality 1 year after diagnosis. Methods: A cohort of 502 newly diagnosed breast cancer patients was prospectively followed. Sleep quality was evaluated with the Pittsburgh Sleep Quality Index (PSQI), at baseline and at the 1-year follow-up. Odds ratios (OR) were computed to quantify the association between patient characteristics and poor sleep quality (PSQI score >5) at baseline, and relative risks (RR) were computed for the association between treatments and the occurrence of poor sleep quality at 1 year. Results A total of 60.2% of the patients had poor sleep quality before breast cancer treatments, especially those with anxiety [OR = 2.86, 95% confidence interval (95%CI) 1.92 to 4.27] or depression (OR = 5.25, 95%CI 2.01 to 13.67). Radiotherapy increased the risk of poor sleep quality at 1 year (RR = 3.71, 95%CI 1.15 to 11.96, for a cumulative dose >50 Gy) and there was a tendency for a higher risk in those submitted to chemotherapy, although not statistically significant. Conclusions Our study shows that sleep disturbances are frequent before cancer treatment and confirms their co-occurrence with other medical conditions, such as anxiety and depression. Different breast cancer treatments increase the risk of impaired sleep quality, therefore contributing to the global disability associated with cancer treatments.FF and ARC have received co-funded by the BFundação para a Ciência e a Tecnologia^ and the POPH/FSE Program (grant numbers SFRH/BD/92630/2013 and SFRH/BD/102181/2014, respectively). Data management activities were supported by the Chair on Pain Medicine of the Faculty of Medicine, University of Porto and by the Grünenthal Foundation – Portugal