The incidence of thrombocytopenia in adult patients receiving chemotherapy for solid tumors or hematologic malignancies

To estimate the risk of thrombocytopenia in various cancers and chemotherapy regimens.Structured patient-level data from the Flatiron Health Electronic Health Record database were used to identify adult patients who received chemotherapy for a solid tumor or hematologic malignancy from 2012 to 2017. Three-month cumulative incidence of thrombocytopenia was assessed based on platelet counts, overall and by grade of thrombocytopenia. Co-occurrence of anemia, neutropenia, and leukopenia was evaluated.Of 15,521 patients with solid tumors, 13% had thrombocytopenia within 3 months (platelet count < 100 × 109 /L); 4% had grade 3 (25 to < 50 × 109 /L), and 2% grade 4 (<25 × 109 /L) thrombocytopenia. Of 2537 patients with hematologic malignancies, 28% had any thrombocytopenia, 16% with grade 3, and 12% with grade 4. Among patients with thrombocytopenia, it occurred without another cytopenia in 18% of solid tumors and 7% of hematologic malignancies.In a large, US-representative sample of patients undergoing chemotherapy in clinical practice, thrombocytopenia incidence varied across tumor and regimen types. Despite recommendations to alter chemotherapy to avoid severe thrombocytopenia, 4% of patients with solid tumors and 16% with hematologic malignancies experienced grade 3 thrombocytopenia. Prediction and prevention of thrombocytopenia may help oncologists avoid dose modifications and their adverse effects on survival.