Docetaxel With or Without Vandetanib in Treating Patients With Metastatic Stomach Cancer or Gastroesophageal Junction Cancer

RATIONALE: Drugs used in chemotherapy, such as docetaxel, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Vandetanib may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth and by blocking blood flow to the tumor. It is not yet known whether docetaxel is more effective when given together with or without vandetanib. PURPOSE: This randomized phase II trial is studying docetaxel to see how well it works compared with docetaxel given together with vandetanib in treating patients with metastatic stomach cancer or gastroesophageal junction cancer.