AbstractBackgroundPatients with cancer are managed across the whole healthcare spectrum. This complex system of interdependencies has high potential for errors to occur. This is a focus area for pharmacists, who possess the skillset to optimise cancer care across the health care system, identifying errors and other medication‐related problems (MRP).AimThe aim of this study was to identify and describe the impact of the pharmacist’s contribution in reducing cancer therapy‐related errors.MethodsA search of English‐language publications in Embase, Medline and CINAHL was conducted. Databases were searched from 1 January 2010 until 29 September 2020 to identify all quantitative studies of a descriptive, observational or experimental design. Articles describing pharmacist‐led interventions in adults receiving one or more cancer therapies including oral chemotherapy, intravenous chemotherapy or immunotherapy compared to no intervention, usual care or a service delivered by another healthcare professional were included. Researchers screened articles to identify eligible studies, and then data were extracted using a standardised data collection sheet. Quality assessment was undertaken using the modified Cochrane and the Newcastle Ottawa risk of bias tools. Data were reported as number or percentage.ResultsOf 2292 papers identified, nine studies were eligible for inclusion in this review. Pharmacist interventions consistently showed an increased identification of medication errors and medication‐related problems. Pharmacist contributions in many of the included studies comprised medication reviews and monitoring, laboratory monitoring, adverse drug reaction and drug–drug interaction management, adherence monitoring and medication counselling. All studies showed pharmacist intervention in cancer care resulted in fewer errors compared to control arms. Error minimisation was described for parenteral and oral cancer therapies and also for supportive medications such as antiemetics.ConclusionPharmacists reduce errors and potential patient harm in practice settings where cancer patients are treated. Pharmacists are an integral component of cancer care teams.