Study of Stereotactic Body Radiation Therapy in Patients With Intact Pancreatic Cancer

Inclusion Criteria:

* Patients must have histologically confirmed, unresected cancer of the pancreas or ampulla. The cancer may include any invasive histology (e.g. adenocarcinoma, neuroendocrine carcinoma).
* Patients must have measurable radiographic disease.Patients with previous complete resection are only eligible if there is measurable radiographic disease which is clearly felt to represent locally recurrent disease.
* Patients may receive any number of cycles of chemotherapy prior to treatment with SBRT, but not within 2 weeks of the first fraction of RT.
* Age \> or = 18 years.
* Eastern Cooperative Oncology Group (ECOG) performance status \< or = 2 (Karnofsky \> or = 60%)
* Life expectancy of greater than 3 months.
* Patients must have normal organ and marrow function.
* Ability to understand and the willingness to sign a written informed consent document.

Exclusion Criteria:

* Concurrent investigational therapy delivered over the period of treatment or observation (28 days post-RT) for dose limiting toxicity.
* Prior radiation therapy to the abdominal area which would overlap with the proposed area of treatment.
* Pregnancy.
* Primary disease \> 7.5 cm in largest diameter as measured by CT or MRI.
* Gross extension of tumor into the lumen of the duodenum.
* Uncontrolled intercurrent illness including, but not limited to ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements.
* Use of bevacizumab or vascular endothelial growth factor inhibitor chemotherapy within 3 months before RT or 6 months after RT.