Impact of Adjuvant Hormone Therapy on Sleep, Physical Activity, and Quality of Life in Premenopausal Breast Cancer: 12-Month Observational Study

Purpose: This study aimed to investigate the differences in sleep disturbance changes between patients receiving two hormone therapies ("tamoxifen plus ovarian function suppression group [T+OFS group]" versus "tamoxifen group [T group]") and the chronological changes in sleep disturbances in each group.Methods: Premenopausal women with unilateral breast cancer who underwent surgery and were scheduled to receive hormone therapy (HT) with tamoxifen alone or with tamoxifen plus gonadotropin-releasing hormone (GnRH) agonist for ovarian function suppression were included. The enrolled patients wore an actigraphy watch for two weeks and completed questionnaires (insomnia, sleep quality, physical activity [PA], and quality of life [QOL]) at five time points: immediately before HT and 2, 5, 8, and 11 months after HT.Results: Among the 39 enrolled patients (21 and 18 patients in the T+OFS group and T group, respectively), 25 (17 and 8 patients in the T+OFS group and T group, respectively) were finally analyzed. There were no differences between the two groups in time-dependent changes in insomnia, sleep quality, total sleep time, rapid eye movement sleep rate, QOL, and PA; however, the severity of hot flashes was significantly higher in the T+OFS group than in the T group. Although the interaction between group and time was not significant, insomnia and sleep quality significantly worsened at 2-5 months of HT when changes over time were analyzed within the T+OFS group. In both the groups, PA and QOL were maintained without significant changes.Conclusion: Unlike tamoxifen alone, tamoxifen plus GnRH agonist initially worsened insomnia and sleep quality, but gradually improved with long-term follow-up. Patients who initially experience insomnia during tamoxifen plus GnRH agonist administration can be reassured based on the results of this study, and active supportive care may be used during this period.Trial Registration: ClinicalTrials.gov Identifier: NCT04116827