AbstractBackgroundChemotherapy‐induced thrombocytopenia (CIT) is a known hematologic complication of oncology treatment. This single‐institution study examines the degree with which CIT impacts specific pediatric solid tumor cohorts reflected by platelet transfusion burden and treatment modifications.ProcedureData regarding clinically relevant CIT were obtained via a retrospective chart review of pediatric solid tumor patients treated at Memorial Sloan Kettering Cancer Center from 2013 to 2020. Patients were stratified based on histologic diagnoses as well as chemotherapy regimen. CIT impact was assessed through platelet transfusion means, chemotherapy dose reductions, and treatment delays.ResultsA total of 150 patients were included with mean age 10.3 [0.2–21.0]. Patients receiving therapy for high‐risk neuroblastoma and localized Ewing sarcoma, both of which included high‐dose cyclophosphamide and doxorubicin, required the most platelet transfusions over the treatment course, with a mean of 13 and 9, respectively. Reduced relative dose intensity (RDI), due in part to CIT, was greatest for the patients receiving therapy for high‐risk and intermediate‐risk rhabdomyosarcoma. Fifty‐six percent of high‐risk patients experienced a reduced RDI during the final two cycles of treatment and 69% of intermediate‐risk patients experienced one during the final four cycles of treatment.ConclusionsThe impact of CIT varied by the administered chemotherapy regimens and dose intensity of chemotherapy agents. This study demonstrated that CIT causes both marked platelet transfusion burden as well as treatment reduction and delay within certain solid tumor cohorts. This can lend to future studies aimed at reducing the burden of CIT and targeting the most at‐risk populations.