ContextFatigue is one of the most uncomfortable physical symptoms seen in patients with advanced cancer. Previous studies have reported on the efficacy of corticosteroids from Western countries. ObjectivesTo assess the effectiveness of 4mg betamethasone improving fatigue among Japanese patients with advanced cancer. MethodsA randomized, double-blind, placebo-controlled trial enrolled eligible patients with advanced cancer expected to survive 1–2 months, with an Eastern Cooperative Oncology Group Performance Status of 2–3, and experiencing fatigue according to the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Core-15-palliative criteria. Participants received twice-daily oral administration of 2 mg betamethasone (4 mg/d) or placebo for seven days, with fatigue assessed using EORTC QLQ-C15-PAL subscale and numerical rating scale (NRS) score (at baseline and day seven). The trial was registered under the University Hospital Medical Information Network (UMIN)000011913. ResultsAmong the 267 screened patients, 81 were eligible, of which 70 were evaluable (betamethasone, 33; placebo, 37). The mean difference in the EORTC-QLQ-C15-PAL fatigue subscale was −8.2 (95% CIs: −22.3, 0.0; P = 0.178) and in a NRS for fatigue was −1.2 (95% CIs: −2.5, −0.01; P = 0.048), respectively. Emotional function, appetite loss, and global-health were slightly better in the betamethasone group than in the placebo group. ConclusionThe impact of betamethasone 4 mg/d on alleviating fatigue in patients with advanced cancer in the last weeks of life did not reach statistical significance in the EORTC-QLQ-C15-PAL as the primary endpoint, however, it was significant in the NRS, the secondary endpoint.