Purpose
This systematic review updates the MASCC/ESMO recommendations for high-emetic-risk chemotherapy (HEC) published in 2016–2017. HEC still includes cisplatin, carmustine, dacarbazine, mechlorethamine, streptozocin, and cyclophosphamide in doses of > 1500 mg/m2 and the combination of cyclophosphamide and an anthracycline (AC) in women with breast cancer.

Methods
A systematic review report following the PRISMA guidelines of the literature from January 1, 2015, until February 1, 2023, was performed. PubMed (Ovid), Scopus (Google), and the Cochrane Database of Systematic Reviews were searched. The literature search was limited to randomized controlled trials, systematic reviews, and meta-analyses.

Results
Forty-six new references were determined to be relevant. The main topics identified were (1) steroid-sparing regimens, (2) olanzapine-containing regimens, and (3) other issues such as comparisons of antiemetics of the same drug class, intravenous NK1 receptor antagonists, and potentially new antiemetics. Five updated recommendations are presented.

Conclusion
There is no need to prescribe steroids (dexamethasone) beyond day 1 after AC HEC, whereas a 4-day regimen is recommended in non-AC HEC. Olanzapine is now recommended as a fixed part of a four-drug prophylactic antiemetic regimen in both non-AC and AC HEC. No major differences between 5-HT3 receptor antagonists or between NK1 receptor antagonists were identified. No new antiemetic agents qualified for inclusion in the updated recommendations.