Inclusion Criteria:

3.1.1 Histologically confirmed adenocarcinoma of the pancreas.

3.1.2 Unresectable disease as determined by a pancreatic cancer surgeon and assessment at
a GI oncology tumor board (JHU, SU, or MSKCC).

3.1.3 Up to 3 weeks of gemcitabine chemotherapy is allowed prior to SBRT.

3.1.4 Pancreatic tumors must be less than 7.5 cm in greatest axial dimension (or <1000 cc
in volume) at the time of treatment planning.

3.1.5 No prior upper abdominal or liver radiation therapy.

3.1.6 No chemotherapy within 2 weeks of radiotherapy, or chemotherapy within parameters
set by Investigator for each institution.

3.1.7 Age >=18 years.

3.1.8 No infections requiring systemic antibiotic treatment.

3.1.9 Karnofsky >= 70% (see Appendix III).

3.1.10 Patients must have acceptable organ and marrow function as defined below (within 1
month prior to radiotherapy):

- leukocytes: >=3,000/uL

- absolute neutrophil count: >=1,500uL

- platelets: >=100,000/uL

- total bilirubin: within 1.5X normal institutional limits

- 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 m^2 for patients with creatinine levels above
institutional normal

3.1.11 The effects of radiation on the developing human fetus at recommended therapeutic
doses can result in death of the fetus. If a woman is of child-bearing potential, a
negative urine or serum pregnancy test must be demonstrated prior to treatment. Women of
childbearing potential and men must agree to use adequate contraception (hormonal or
barrier method of birth control; abstinence) for the duration of study participation and
for up to 4 weeks following the study. Should a woman become pregnant or suspect she is
pregnant while participating in this study, she should inform her treating physician
immediately.

3.1.12 Ability to understand and the willingness to sign a written informed consent
document.

3.1.13 Life expectancy > 6 months

Exclusion Criteria:

3.2.1 Patients who have had prior radiotherapy to the upper abdomen.

3.2.2 Patients receiving more than 1 cycle of gemcitabine chemotherapy or other therapy
prior to SBRT.

3.2.3 Children are excluded because pancreatic tumors rarely occur in this age group.
Furthermore, treatment requires a great deal of patient cooperation including the ability
to lie still for several hours in an isolated room.

3.2.4 No laboratory personnel will be included.

3.2.5 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.

3.2.6 Any concurrent malignancy other than non-melanoma skin cancer, non-invasive bladder
cancer, or carcinoma in situ of the cervix. Patients with a previous malignancy without
evidence of disease for > 5 years will be allowed to enter the trial.

3.2.7 Pregnant and breastfeeding women are excluded. Women of child-bearing potential who
are unwilling or unable to use an acceptable method of birth control to avoid pregnancy
for the entire study period and for up to 4 weeks after the study are excluded. This
applies to any woman who has experienced menarche and who has not undergone successful
surgical sterilization or is not postmenopausal (defined as amenorrhea for at least 12
consecutive months, or women on hormone replacement therapy with serum FSH levels greater
than 35 mIU/mL. A negative urine or serum pregnancy test must be obtained within 72 hours
prior to the start of study medication in all women of childbearing potential. Male
subjects must also agree to use effective contraception for the same period as above.