Colony-Stimulating Factors During Radiotherapy and Chemoradiotherapy: Are Historical Concerns Still Justified?

Abstract

The use of colony-stimulating factors (CSFs) during radiotherapy (RT), particularly concurrent chemoradiotherapy (CRT), has historically been approached with caution because of toxicity concerns reported in earlier studies. However, much of the evidence underlying this caution predates contemporary radiation techniques and does not consistently distinguish granulocyte colony-stimulating factor (G-CSF) from granulocyte-macrophage colony-stimulating factor (GM-CSF). This brief review examines contemporary evidence regarding the safety and potential clinical utility of CSFs administered during RT and CRT. Available data suggest that G-CSF and pegylated G-CSF may reduce severe neutropenia and treatment interruptions in selected clinical settings, including craniospinal irradiation, pelvic CRT, and head and neck cancer, without consistently increasing clinically significant radiation-related toxicity. However, thoracic CRT, particularly when substantial mediastinal marrow is irradiated, remains a setting in which hematologic toxicity, including thrombocytopenia and transfusion requirements, warrants particular attention. Overall, current evidence does not support a uniform prohibition of CSF administration during RT or CRT, but neither does it establish routine prophylactic use for all patients. Decisions should be individualized according to treatment regimen, irradiated marrow volume, prior and concurrent chemotherapy, baseline hematologic risk, treatment intent, and the clinical consequences of treatment interruption. Further prospective comparative studies employing contemporary RT techniques are needed to firmly establish safety across diverse clinical settings.