Chemotherapy With or Without Radiation or Surgery in Treating Participants With Oligometastatic Esophageal or Gastric Cancer

This phase II trial studies how well chemotherapy with or without radiation or surgery works in treating participants with esophageal or gastric cancer that has spread to less than 3 places in the body (oligometastatic). Drugs used in chemotherapy, such as fluorouracil and capecitabine, work in different ways to stop the growth of tumor cells, either by killing the cells, by stopping them from dividing, or by stopping them from spreading. Radiation therapy uses high energy x-rays to kill tumor cells and shrink tumors. Surgery, such as complete surgical resection, may stop the spread of tumor cells by surgically removing organs or tumors. Giving chemotherapy with radiation or surgery may work better than chemotherapy alone in treating participants with oligometastatic esophageal or gastric cancer.