Phase II Study to Evaluate Modified Folfirinox and Stereotactic Body Radiation Therapy in Non-metastatic Unresectable Pancreatic Adenocarcinoma

Inclusion Criteria: * Histologically confirmed pancreatic adenocarcinoma * Borderline resectable pancreatic adenocarcinoma or locally advanced pancreatic adenocarcinoma * No evidence of extrapancreatic disease on diagnostic imaging * No evidence of invasion into the duodenum or stomach, as determined by EGD/EUS * No prior treatment (chemotherapy, biological therapy, or radiotherapy) for pancreatic cancer * No prior treatment with oxaliplatin, irinotecan, fluorouracil, or capecitabine * ECOG Performance Status of 0-1 * No other malignancy within past five years (exceptions include basal cell carcinoma of the skin, cervical carcinoma in situ, and non-metastatic prostate cancer) * No evidence of second malignancy at the time of study entry * No interstitial pneumonia or extensive and symptomatic interstitial fibrosis of the lung * No \> grade 2 sensory peripheral neuropathy * No uncontrolled seizure disorder, active neurological disease, or known CNS disease * No significant cardiac disease, including the following: unstable angina, New York Heart Association class II-IV congestive heart failure, myocardial infarction within six months prior to study enrollment * Not pregnant and not nursing * No other medical condition or reason that, in the opinion of the investigator, would preclude study participation * Laboratory parameters as follows: * Absolute neutrophil count ≥1,500/uL, * Platelet count ≥75,000/uL, * Hemoglobin ≥9 g,/dL, * Creatinine \<1.5 X ULN or estimated GFR \>30 ml/min, * Bilirubin \<1.5 X ULN, * AST and ALT \<3 X ULN, * Negative pregnancy test in women of childbearing potential * Able to be treated with SBRT only at the Smilow New Haven campus * Able to have fiducials placed in the pancreas Exclusion Criteria: * Failing to meet any of the Inclusion Criteria