Chemotherapy and Radiation Therapy (RT) With or Without Vandetanib in Treating Patients With High-Risk Stage III or Stage IV Head and Neck Cancer

RATIONALE: Drugs used in chemotherapy, such as cisplatin, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Radiation therapy uses high-energy x-rays to kill tumor cells. Vandetanib may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth. It is not yet known whether giving chemotherapy together with radiation therapy is more effective with or without vandetanib in treating patients with head and neck cancer. PURPOSE: This randomized phase II trial is studying giving chemotherapy together with radiation therapy to see how well it works compared with giving chemotherapy and radiation therapy together with vandetanib in treating patients with high-risk stage III or stage IV head and neck cancer.