Stereotactic body radiation therapy: a comprehensive review.

Stereotactic body radiation therapy (SBRT) is a novel technique that takes advantage of the technologic advancements in image guidance and radiation dose delivery to direct ablative doses to tumors with acceptable toxicity that was not previously achievable with conventional techniques. SBRT requires a high degree of confidence in tumor location provided by high quality diagnostic and near real-time imaging studies for accurate treatment delivery and precise assessment of physiologic tumor motion. In addition, stringent dosimetric parameters must be applied, paying close attention to the spatial arrangement of functional subunits in the adjacent normal tissues, to optimize clinical outcomes. Phase I/II trials for tumors of the lung, liver, spine, pancreas, kidney, and prostate provide evidence that the potent doses delivered with SBRT may provide results that rival surgery while avoiding the typical morbidities associated with that invasive approach. Further clinical study in the form of multi-institutional Phase II trials is currently underway, and ultimately collaborative efforts on a national level to support Phase III trials will be necessary, to firmly establish SBRT as a comparable noninvasive alternative to surgery.