The goal of this clinical trial is to improve and personalize pancreatic cancer care to deliver the most effective therapy while avoiding unnecessary exposure to potential side effects. Excision repair cross-complementation group 1 (ERCC1) protein and mRNA expression predicts response to oxaliplatin - patients whose cancers make small amounts of ERCC1 are much more likely to respond to cisplatin than those whose tumors produce large amounts. The hypothesis is that the combination of gemcitabine and oxaliplatin is a uniquely effective regimen for patients with metastatic pancreatic cancer whose tumors have a low expression of ERCC1.