The Relationship Between Changes in Physical Activity and Physical and Mental Health in Female Breast Cancer Survivors Undergoing Long-Term Activity Restrictions in Japan.

: Exercise is recommended for survivors of breast cancer to alleviate adverse reactions and reduce the psychological burden. In recent years, however, environmental factors (e.g., pandemics and climate change) have made it difficult to exercise outdoors. Therefore, this study focused on the COVID-19 pandemic in Japan and evaluated the relationship between changes in physical activity (PA) and mental and physical health in breast cancer survivors. : A questionnaire survey was conducted among 345 outpatient female breast cancer survivors aged between 29 and 69 years. The questionnaire was based on the International Physical Activity Questionnaire, the Patient Health Questionnaire-9, the European Organization for Research and Treatment of Cancer Core Quality of Life Questionnaire, and the Fear of COVID-19 Scale and included patient characteristics, changes in PA during pandemic restrictions, and needs for exercise support. The analysis categorized PA changes into two groups according to activity levels. The relationship between changes in PA and physical and mental health was evaluated using logistic regression analysis. : Patients with decreased PA accounted for 65.5% of the study population. Regardless of their activity level, these patients were aware of an increased susceptibility to COVID-19, showed a fear of the disease and a tendency for depression, and reported low life satisfaction and declined physical function. Of the patients who stopped exercising, 82.9% reported a decline in PA. Compared with those who had never exercised, those who stopped exercising saw their risk of depression increase by 15.6%. There was a high demand for personalized exercise support from healthcare professionals. : Regardless of their activity level, decreasing PA during the pandemic decreased mental health and physical function in breast cancer survivors. There was a higher risk of depression among patients who stopped exercising. Because it is possible that similar situations may occur in the future, interventions by healthcare professionals must be considered in order to continue exercise.