Stereotactic body radiation therapy

Stereotactic body radiation therapy constitutes an emerging therapeutic paradigm. These treatments are unique relative to the large body of experience with conventional fractionated radiotherapy. On the basis of the treatment principles of intracranial stereotactic radiation combined with enhancements associated with immobilization and imaging, the role of extracranial treatment continues to evolve. However, most clinical reports on extracranial treatments suffer from short or incomplete follow-up, making final assessments of benefit and toxicity, particularly late toxicity, problematic. These techniques are centered on a very basic understanding of the use of ionizing radiation for the treatment of cancer. Nonetheless, they do require a unique and special understanding of radiobiologic and physics principles. It is hoped that using high-dose, single-fraction treatment or a few fractions of treatment, the therapeutic ratio is improved, thus potentially changing the way some cancers are treated. Ideally, all patients receiving such treatments would be enrolled in formal protocols. As data accrue and understanding of these techniques improve, it will be possible to better define the indications for stereotactic body radiation therapy. At that time, appropriate applications can be submitted for permanent billing codes that will describe a process of care that embraces this technology without vendor favoritism. This review summarizes the state of stereotactic body radiation in 2005.