Laparoscopic Hyperthermic Intraperitoneal Chemoperfusion (HIPEC) for Metastatic Gastric Cancer

HIPEC Treatment: If you are found to be eligible to take part in this study, on the day of HIPEC treatment, you will receive heated mitomycin-C and cisplatin as a liquid that is injected through 3 to 4 small incisions in your abdomen for about 1 hour. This will be done as a surgical procedure, and you will be under general anesthesia. The chemotherapy will then be flushed out of your abdomen and collected, and the treatment area inside your abdomen will be washed. Also during the HIPEC procedure, fluid will be collected and checked for cancer cells. As is standard of care, any lesions that are found during treatment may also be biopsied at this time, if the study doctor thinks it is necessary. You may receive up to 5 HIPEC treatments on this study. You will also receive sodium thiosulfate by vein over about 20 minutes to protect the kidneys. You will remain in the hospital for 3-7 days after treatment. While you are in the hospital after surgery: * Blood (about 2-3 tablespoons) may be drawn for routine tests, if the study doctor thinks it is necessary. Study Visits: One (1) time between Weeks 2-6: * You will have a physical exam. * Blood (about 2-3 tablespoons) will be drawn for routine tests. Gastrectomy Surgery: If your doctor thinks it is needed, you will have a standard of care surgery. You will receive a separate consent form which explains the surgery and its risks. On or before 8 weeks after your surgery: * You will have a physical exam. * Blood (about 2-3 tablespoons) will be drawn for routine tests. Follow-Up Visits: You will have routine clinic visits every 6 months from the date of your last surgery. You will be asked about any other cancer treatments you may be receiving. If you stopped the study early, the study doctor may ask you to return to the office for extra CT scans, PET scan, or MRIs during the follow-up period. You will have a CT scan, PET scan, or MRI of your chest, abdomen, and pelvis every 6 months for 5 years after surgery to check the status of the disease. Length of Study Participation: You will be on study for about 5 years after your last surgery. You will be taken off study early if the disease gets worse, if intolerable side effects occur, or if you are unable to follow study directions. Your participation on the study will be over after the follow-up visits. This is an investigational study. The chemotherapy and surgery are standard treatment for stomach and gastroesophageal cancer. It is investigational to give the chemotherapy by HIPEC. Up to 30 participants will take part in this study. All will be enrolled at MD Anderson.