Chemotherapy, Stereotactic Body Radiation Therapy & Nelfinavir Mesylate in Locally Advanced Pancreatic Cancer

Inclusion Criteria: * Pathologically confirmed adenocarcinoma of the pancreas; patients have resectable borderline resectable disease, or unresectable disease with no evidence of distant metastases or peritoneal disease; the maximum dimension of the tumor must be =\< 10 cm * Karnofsky performance status of 60% or better * Patients who received chemotherapy \> 5 years ago for malignancies other than pancreatic cancer are eligible, provided that chemotherapy was completed \> 5 years ago and that there is no evidence of the second malignancy at the time of study entry * Patients who received radiation therapy \> 5 years ago for malignancies other than pancreatic cancer and whose radiation therapy field is not overlapping with the 20% isodose line of current radiation field are eligible, provided that radiation therapy was completed \> 5 years ago and that there is no evidence of the second malignancy at the time of study entry * All malignant disease must be able to be encompassed within a single irradiation field * All patients must have radiographically assessable disease * Absolute neutrophil count (ANC) greater than or equal to 1500/uL * Platelet count greater than or equal to 100,000/uL * Serum creatinine less than or equal to 2.0 mg/dL * Total bilirubin less than or equal to 2.0 mg/dL in the absence of biliary obstruction; if the patient has biliary obstruction, biliary decompression will be required; either endoscopic placement of biliary stent (7 French or greater) or p…