Neuropathic pain after breast cancer treatment and its impact on sleep quality one year after cancer diagnosis

Objectives: Data regarding the impact of breast cancer treatment-related neuropathic pain (NP) on sleep quality are scarce. Therefore, we aimed to assess the impact of breast cancer treatment-related NP on patients' sleep quality, during the first year after cancer diagnosis. Materials and methods: A total of 501 breast cancer patients were followed prospectively. Incident NP was identified through systematic evaluations after treatments and one year after enrolment. NP severity was quantified using the Brief Pain Inventory severity subscale and sleep quality was evaluated through the Pittsburgh Sleep Quality Index (PSQI), at baseline and after one year. Adjusted regression coefficients (β) and 95% confidence intervals (95%CI) were used to quantify the relation between NP and the variation in the PSQI z-scores. Results: The occurrence of NP was associated with a deterioration in sleep quality during the first year of follow-up, more pronounced among those with good sleep quality (PSQI≤5) than those with poor sleep quality at baseline (PSQI>5) (β = 0.44, 95%CI: 0.11 to 0.77 versus β = 0.33, 95%CI: 0.08 to 0.59). These differences were accentuated when only the cases of NP with greater severity were considered (β = 0.86, 95%CI: 0.37 to 1.35 versus β = 0.31, 95%CI: −0.08 to 0.64). Within the PSQI components, daytime dysfunction and sleep duration were the most impaired by NP. Conclusion: Our findings highlight the importance of the promotion of sleep hygiene among breast cancer patients diagnosed with NP, especially among those with good sleep quality before treatments.This study was funded by FEDER through the Operational Programme Competitiveness and Internationalization (POCI-01-0145-FEDER-016867) and national funding from the Foundation for Science and Technology – FCT (Portuguese Ministry of Science, Technology and Higher Education) (PTDC/DTP-EPI/7283/2014) under the Unidade de Investigação em Epidemiologia - Instituto de Saúde Pública da Universidade do Porto (EPIUnit) (POCI-01-0145-FEDER-006862; Ref.UID/DTP/04750/2013); the PhD Grant SFRH/BD/92630/2013 (Filipa Fontes) co-funded by the FCT and the POPH/FSE Program. 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