In the past twenty years, significant advancements in cancer treatment have been achieved. New surgical techniques such as robotic surgery [1], three-dimensional magnification, and intraoperative imaging have resulted in less invasive and more effective surgical procedures for the resection of both primary tumors and metastatic disease. Promising novel cytotoxic agents, including cancer-specific molecular targeting agents [2], have been discovered and continue to be investigated. Moreover, radiation therapy has undergone rapid advancement in its targeting capabilities with the introduction of technologies such as 3D-conformal radiotherapy, intensity-modulated radiotherapy, image-guided radiotherapy, and stereotactic body radiosurgery.

Metastatic disease presents a challenging therapeutic situation. Often, patients have widespread systemic disease without abundant treatment options. However, radiotherapy, first applied in cancer treatment more than one hundred years ago, has played an important role in patients with metastatic disease. Its primary use has been to efficiently provide palliation of symptoms such as pain, obstruction, bleeding, and intracranial pressure. Small doses of radiation have been given to provide effective relief of symptoms in patients who often have a high burden of disease and to minimize the impact on normal tissues. Recent improvements in both cytotoxic agents and targeting methods in radiotherapy have extended the survival time in patients with metastatic disease. Typical palliative doses of radiation such as 30 Gy in ten fractions, although effective at relieving symptoms, have been unable to biologically control disease on a long-term basis.