Combined treatment with cytoprotective agents and radiotherapy

Radiotherapy is associated with several toxicities affecting healthy tissues. One of the strategies aimed at decreasing radiation toxicity is the use of radioprotective agents, such as amifostine and palifermin, or factors stimulating hemopoetic stem cells (colony stimulating factors, CSFs): granulocyte-CSF, granulocyte macrophage-CSF and recombinant erythropoetins. The potential beneficial effect of these substances demonstrated in preclinical in vitro and in vivo studies led to numerous clinical trials. This review addresses the current experience on the use of cytoprotective agents in combination with radiotherapy, with particular focus on the safety of these approaches. Despite a relatively large body of literature data, the role of cytoprotective agents combined with radiotherapy remains controversial. Overall, their use in this application is still limited due to modest radioprotective effect for normal tissues, potential risk of tumor protection and increased treatment toxicity. The use of erythropoetins in combination with radiotherapy should generally be discouraged, whereas the safe and effective application of other agents warrants further investigations.