Evaluation of the Efficacy of 2.5 mg Olanzapine to Prevent Anthracycline and Cyclophosphamide Combination Therapy-induced Nausea and Vomiting

This study aims to compare the antiemetic efficacy of a four-drug combination with that of a standard three-drug combination in Japanese breast cancer patients, who received their first cycle of anthracycline and cyclophosphamide combination therapy and were treated with granisetron, dexamethasone, and aprepitant with or without 2.5 mg olanzapine. This retrospective observational study was performed at Hamanomachi Hospital using the electronic medical records of 71 patients who were divided into two groups, ie, the four- and three-drug groups comprising 31 and 40 patients, respectively. The complete response (CR: no emesis and no use of rescue medications) rate in the delayed phase (24 – 120 h after the start of chemotherapy) was 77.4％ and 47.5％ in the four- and three-drug groups (P = 0.014), respectively. A multivariable logistic regression analysis showed that the four-drug group was significantly associated with an increased odds of CR achievement in the delayed phase (odds ratio: 5.61, 95％ confidence interval: 1.63 – 19.3). Additionally, daytime somnolence had 41.2％ incidence in 72 h after chemotherapy administration, but 32.4％ of patients continued. These findings suggest that the antiemetic efficacy of the four-drug combination is superior to that of the standard three-drug combination.