The accidental or hostile exposure of individuals to ionizing irradiation is of great public and military concern. Radiation sickness (acute radiation syndrome, or ARS) occurs when the body is exposed to a high dose of penetrating radiation within a short period of time. Systemic infection is one of the serious consequences of ARS. There is a direct relation between the magnitude of radiation exposure and the risk of developing infection. The risk of systemic infection is higher whenever there is a combined injury such as burn or trauma. Ionizing radiation enhances infection by allowing translocation of oral and gastrointestinal flora, and reducing the threshold of sepsis due to endogenous and exogenous microorganisms. The potential for concomitant accidental or terrorism-related exposure to bio-terrorism agents such as anthrax and radiation also exists.

This site is made of a home page that presents new developments and updates on the management of acute radiation syndrome including concomitant exposure to radiation and anthrax. Separate pages are dedicated to the treatment modalities.

Neutropenia: Cytokine Therapy with G-CSF or GM-CSF

Although not FDA approved for the management of radiation-induced marrow aplasia, hematopoietic growth factors, e.g., granulocyte colony stimulating factor (G-CSF) and granulocyte macrophage colony stimulating factor (GM-CSF), have been used in the aftermath of a number of radiation accidents to include Chernobyl and Goiania in an effort to lessen the severity and duration of neutropenia, and thereby lessen the risk of infection. 

The experience with these few clinical cases along with even more convincing data in controlled studies in canines and non-human primates suggest survivability can be significantly enhanced when early cytokine therapy is instituted, with maximal benefit shown if given within the first 24 to 72 hours ( National Council on Radiation Protection and Measurements. Management of Terrorist Events Involving Radioactive Material, NCRP Report No. 138,  Bethesda, MD:  National Council on Radiation Protection and Measurements:  2001; Aapro et al. EORTC guidelines for the use of granulocyte-colony stimulating factor to reduce the incidence of chemotherapy-induced febrile neutropenia in adult patients with lymphomas and solid tumours. Eur J Cancer. 2006 ;42: 2433). 

In the absence of significant complicating injuries, the recommended exposure threshold for cytokine therapy is 3 Gy, with some recommendations for intervention in the more susceptible pediatric patient at 2 Gy ( Hall EJ. Acute effects of total-body irradiation in Radiobiology for the Radiologist. Philadelphia:  Lippincott Williams and Wilkins; 2000). 

Practical limitations such as the number of victims outstripping cytokine availability will need to be considered when determining at what level of exposure to intervene. Although the long-acting form of G-CSF (pegfilgastrim) has been recently approved as a one dose therapy for the management of chemotherapy-induced neutropenia, it is not currently approved for non-adolescent children. The other two FDA approved cytokines, G-CSF and GM-CSF, are administered daily until an absolute neutrophil count of greater than 1000 is reached. Dosages for children are 5 mcg per kg per day and 250 mg per m2 per day for G-CSF and GM-CSF respectively.