Olanzapine Plus Triple Antiemetic Therapy for the Prevention of Platinum-Based Delayed-Phase Chemotherapy-Induced Nausea and Vomiting: A Meta-Analysis

<b>Background:</b> Chemotherapy-induced nausea and vomiting (CINV) is a common treatment-related side effect that has a detrimental effect on the quality of life of patients with cancer and may lead to dose reductions or discontinuation of chemotherapy. This meta-analysis aims to explore the efficacy and safety of olanzapine plus triple antiemetic therapy for prevention of delayed-phase platinum-based CINV. <b>Methods:</b> Electronic databases (five English databases: (I) PubMed, (II) ScienceDirect, (III) The Cochrane Library, (IV) Scopus, and (V) EMBASE, and two Chinese databases: China National Knowledge Infrastructure and Wanfang Database) were searched for trials that evaluated the effectiveness and safety of olanzapine plus triple antiemetic in preventing platinum-based CINV. Efficacy was no nausea, complete control, and complete response (CR) rates in the acute, delayed, and overall phases after chemotherapy. Data were analyzed using the random effects model and fixed effects model. <b>Results:</b> A total of 18 trials involving 3110 patients were identified, including 9 controlled trials and 9 single-arm trials. The meta-analysis of nine studies, which showed significant heterogeneity (<i>p</i> = 0.002, I² = 67%), demonstrated that the olanzapine (OLN) group had a significantly higher rate of delayed CR compared to the control group (OR: 2.33, 95% CI: 1.57-3.46, <i>p</i> < 0.00001). Compared with the Without OLN group, the With OLN group had a significant overall CR (OR: 2.18, 95% CI: 1.80-2.63, <i>p</i> < 0.00001, heterogeneity: <i>p</i> < 0.00001, I² = 69%), and a significant acute CR (OR: 2.28, 95% CI: 1.45-3.58, <i>p</i> < 0.00001, heterogeneity: <i>p</i> = 0.04, I² = 51%). The meta-analysis revealed that the With OLN group could significantly increase the risk of dry mouth compared to the Without OLN group (OR = 2.60, 95% CI: 1.73-3.91). In terms of insomnia, the odds ratio for the With OLN group was significantly lower than that for the Without OLN group (OR = 0.60; 95% CI 0.41-0.89). <b>Conclusions:</b> The results of this meta-analysis provide robust evidence that adding olanzapine to standard triple therapy significantly improves the prevention of platinum-based delayed-phase CINV, a setting where current antiemetic regimens often prove suboptimal. However, it also increases the risk of certain adverse events, especially dry mouth. Clinical decisions should be made based on a thorough assessment of the therapeutic benefits and safety risks.