Cyberknife Radiosurgery Boost for Hilar Cholangiocarcinoma (Klatskin Tumor)

Inclusion Criteria: * Age eighteen years or older * Histological defined unresectable cholangiocarcinoma of hilar region of the liver * Patients should have evaluable disease on one or more imaging modalities (CT scan, MRI, and/or PET) since this will be necessary for radiation treatment planning. However, because the borders of these tumors are sometimes difficult to define precisely, measurable disease is not required (see Section 9.1 for definitions of evaluable and measurable disease). * The maximum tumor dimension should be less than 6 cm. * Patients with pathologically enlarged perihepatic regional lymph nodes are allowed. * Prior surgical resection is allowed if there is gross disease remaining * Adjuvant chemotherapy is allowed at least 1 month after completion of radiation therapy if any grade 3 or higher toxicity has resolved * Percutaneous biliary drains and biliary stents are allowed * Performance status of ECOG 0-1 (see Appendix I) * Life expectancy greater than 6 months * Subject must have normal organ and marrow functions as defined below * leukocytes \>3,000/mcL * absolute neutrophil count \>1,500/mcL * platelets \>100,000/mcL * total bilirubin \<2.5 X institutional upper limit of normal * AST(SGOT)/ALT(SGPT) \<2.5 X institutional upper limit of normal * creatinine within normal institutional limits OR * creatinine clearance \>60 mL/min/1.73 m2 for patients with creatinine levels above institutional normal. * PT/PTT within normal institutional limits * Gold marker seeds (1 to 3) are required to be placed in or around the primary tumor by an interventional radiologist * Ability to give written informed consent and willingness to comply with the requirements of the protocol * Women of child-bearing potential must agree to use an effective method of birth control during treatment and for six months after receiving their last dose of treatment Exclusion Criteria: * Patients who have had prior chemotherapy * Patients who have had external beam radiation to the region of liver hilar previously. * Patients receiving any other investigational agents * Patients with known metastases * History of allergic reactions attributed to compounds of similar chemical or biologic composition to capecitabine. * 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. * Patients who are not candidates for gold marker seeds placement due to position of the tumor or co-existing medical condition. * Pregnant or lactating women and women of child-bearing potential who are not using an effective method of birth control * Any condition that compromises compliance with the objectives and procedures of this protocol, as judged by the principal investigator