Seasonal fluctuations in psychological distress amongst women diagnosed with early breast cancer receiving radiotherapy

OBJECTIVE: Seasonal effects on patients diagnosed with depression/anxiety-related psychological disorders have varying impacts on symptom severity. Seasonal changes in psychological distress may be due to decreased daylight exposure during the fall/winter seasons. Patients receiving radiation therapy (RT) for early-stage invasive breast cancer (EIBC) are at high risk for developing depressive symptoms. Of interest is whether seasonal factors influence the psychological symptoms of patients being treated for EIBC. METHODS: Patients treated with RT for EIBC between January 2011 and June 2017 were identified. Patients who completed at least one Edmonton Symptom Assessment Scale (ESAS-r) pre-RT and post-RT were included in our analysis. Patients receiving RT during the autumn and winter (November-March) were compared with patients receiving RT during the spring and summer (April-August). Psychological distress was evaluated based on patient-reported depression, anxiety, and overall wellbeing on the ESAS-r. Data on systemic treatment and radiation were extracted from existing databases. RESULTS: Eight-four patients treated with RT in spring/summer and 102 patients treated with RT in autumn/winter were included. Patients receiving RT during spring/summer had better wellness score prior to RT, compared with those receiving RT during winter/autumn (P = .03). However, patients receiving RT in the spring/summer had worse symptom trajectories across three domains of depression, anxiety, and wellbeing (P = .03, P = .008, and P < .0001, respectively). CONCLUSIONS: Seasonality influenced the symptoms reported by patients with EIBC receiving RT. Future studies are needed to understand when during treatment patients are at highest risk for psychological distress and how seasonality may influence high-risk periods.