Oxaliplatin-Based Chemotherapy and Chemoradiotherapy or Chemoradiotherapy in Esophageal or Gastroesophageal Carcinoma

The goal of this clinical research study is to learn if a combination of the investigational drug oxaliplatin with 5-Fluorouracil (5-FU) (given at the same time as radiation therapy) is as effective as a combination of these two drugs given before and during radiation therapy in the treatment of esophageal or gastroesophageal cancers. The safety of these combinations of therapy will also be compared. Objectives: Primary objective: Compare the Pathologic Complete Response rate and % of patients with \<50% residual cancer in the resected surgical specimen between Arms A and B. Secondary objectives: 1. Compare 1-year and 3-year survival rates, median survival time, R0 resection rates, safety, and local plus systemic relapse rates between Arms A and B 2. Perform exploratory correlative studies on blood, adjacent normal and cancer tissue to assess predictive markers of response and outcome. 3. Evaluate the joint effects, including possible interactive effects, of proton-versus-photon therapy and treatment arm on overall survival, R0 resection rates, safety, and local plus systemic relapse rates.