Chemotherapy-Induced & Radiotherapy-Induced Thrombocytopenia

Chemotherapy-induced thrombocytopenia (CIT) is one of the common hematologic toxicity of treatment of cancers and so is radiation induced thrombocytopenia (RIT). The incidence varies from 16% in solid cancers to 68% in hematological malignancies. However, it depends on various host related, disease related and treatment related factors. Amongst them the variables which determine the extent of CIT are; age, associated co-morbidities, type of cancer and its extent, myelosuppressive drugs inclusion in the chemotherapy along with number of prior chemotherapy cycles, and bone marrow involvement. The severity of thrombocytopenia is related to the type and dose of chemotherapy. This is observed with increased incidence with certain regimens containing gemcitabine, platinum, or temozolomide or newer immunotherapeutic agents’ application. Platelet PF4 levels are inversely related to nadir of platelet counts and its level increases after radiotherapy. At the same time thrombocytopenia is considered as one of the risk factor causing bleeding. During the post chemotherapy period, it is important to exclude the other causes of thrombocytopenia like use of other causative drugs, infection and its severity, thrombotic microangiopathy, coagulopathy and immune thrombocytopenia. Once the other conditions are excluded, then the recommended approach is to reduce chemotherapy dose intensity or switch to other agents if possible. However, decreasing the dose intensity will compromise the response rates. Various recombinant thrombopoietin and thrombopoietin receptor agonist improve platelet counts and reduce the requirement for platelet transfusions. Addition of these novel agents helps to administer the proper dose of chemotherapy in a defined protocol.