In vitro data suggest synergy between oxaliplatin and 5-FU. The combination of oxaliplatin with 5-fluorouracil produced objective response rates ranging from 27-34% in two studies of patients with prior chemotherapy. Capecitabine was designed as an orally administered, tumor selective fluoropyrimidine, preferentially converted to 5-FU at the tumor site by the higher levels of pyrimidine nucleoside phosphorylase (PyNPase) in tumor tissues compared to normal tissues. The end result is higher concentrations of 5-fluorouracil in tumor relative to surrounding normal tissue. This trial will investigate the activity of this novel capecitabine/oxaliplatin (CAPOX) combination in patients with advanced disease. In addition, an exploratory analysis will correlate response with thymidine synthase and thymidine phosphorylase expression in primary tumor samples.