The Use of Stereotactic Body Radiation Therapy in Gastrointestinal Malignancies in Locally Advanced and Metastatic Settings

Gastrointestinal (GI) malignancies are a major cause of cancer morbidity and mortality, with an estimated 275,720 cases and 135,800 deaths in 2009. Treatment of GI malignancies presents a challenge both in the localized and metastatic setting and in formulating new ways to improve local disease control and ultimately overall survival. Among conventional modalities of treatment, such as systemic chemotherapy, fractionated radiation therapy, surgical resection, and nonsurgical invasive means, a new technology has emerged: stereotactic body radiation therapy (SBRT). Its origins stem from the intracranial stereotactic radiosurgery developed in 1950s for the treatment of patients with intracranial malignancies. SBRT is a new and innovative way of delivering high-dose radiation to the extracranial tumor targets in one or few fractions with a high degree of precision. Although SBRT technology such as CyberKnife and Novalis are becoming increasingly popular and widely used, there are limited data that provide comparison with conventional therapy, and no randomized, prospective, multicenter studies that having been conducted in areas of GI malignancies. Current studies that provide data on SBRT use consist of small cohorts of patients, making any assessment of survival inadequate. This article is a technical review of SBRT and will focus on the origins and principles of SBRT, utilization of SBRT technology in local and metastatic settings in GI malignancies, and the examination of local control, median survival, and toxicities. It will review available data and will discuss future directions in the GI field.