The primary objective of this study is to determine the progression free survival in patients with metastatic pancreatic cancer and in patients with locally advanced unresectable non-metastatic pancreatic cancer treated with a dose-attenuated modification of folinic acid, fluorouracil, irinotecan, and oxaliplatin (FOLFIRINOX). Secondary endpoints include: determine objective response rate according to RECIST; determine overall survival; evaluate toxicity; determine rate of resection in locally advanced unresectable stratum; correlate time to progression, objective response, and overall survival with early changes in glucose metabolism using [18F]-fluorodeoxyglucose (FDG)-positron emission tomography (PET) scanning.