[A Case of General Fatigue Caused by Enzalutamide that was Evaluated Using the Cancer Fatigue Scale and Overcome by Switching to Nighttime Treatment].

An 81-year-old man with castration-resistant prostate cancer experienced general fatigue while receiving enzalutamide treatment. In some patients we encountered the enzalutamide treatment had to be interrupted or the dose decreased because of this adverse effect. We evaluated the patient's general fatigue using the Cancer Fatigue Scale (CFS) score and clarified the quantitative information about his general fatigue. In order to maintain the optimal dose, we advised the patient to take enzalutamide at night. This alleviated the adverse effect, and he could maintain the optimal dose of this medicine. We compared the CFS score before and after switching to nighttime treatment and found improvement. This is the first report of a CFS-based evaluation of the improvement in general fatigue caused by enzalutamide by switching to nighttime treatment.