Chemotherapy given together is a standard way to treat gastric (stomach) or gastroesophageal junction (also known as GEJ, the area where the esophagus opens into the stomach) cancer. One standard treatment includes a combination of docetaxel, cisplatin, and fluorouracil. However, the original combination of these three drugs can cause many side effects. This study is being done to find out if these three drugs can be given more safely and with fewer side effects and still maintain the same survival rate benefit as the standard way of giving this three drug combination.