CyberKnife radiosurgery for pancreatic Cancer

Pancreatic cancer remains one of the most lethal cancer diagnoses. The high mortality rate is primarily related to its advanced stage at diagnosis and the high rate of distant metastases. The treatment results of resected and locally advanced pancreatic cancer via conventional chemoradiotherapy have been disappointing, with a high rate of local disease progression and metastases. Past investigation has suggested improved outcomes with radiotherapy dose escalation. Extracranial stereotactic radiosurgery using CyberKnife® (Accuray Incorporated, Sunnyvale, CA) technology is a novel approach to the administration of radiation in a single outpatient treatment, while minimizing the irradiation of surrounding normal structures. Phase I/II studies have shown it to be safe and effective in providing local tumor control and palliation of local symptoms. Furthermore, the decreased treatment time with radiosurgery minimizes the delay in initiation of systemic therapy. The role of pre-operative radiosurgery in combination with gemcitabine chemotherapy has many theoretical advantages over conventional neo-adjuvant or post-operative fractionated radiotherapy in combination with sensitizing chemotherapy. The movement of the pancreas due to respiration poses a challenge in the planning of stereotactic radiosurgery. In this chapter, the use of Image Guided Radiotherapy techniques (IGRT), such as the Synchrony® (Accuray Incorporated, Sunnyvale, CA) Respiratory Motion Tracking system and respiratory gated 4D PET-CT scanning for defining the tumor volume is reviewed.