RATIONALE: Radiation therapy uses high-energy x-rays to damage tumor cells. Drugs used in chemotherapy use different ways to stop tumor cells from dividing so they stop growing or die. Combining chemotherapy with radiation therapy may kill more tumor cells and allow doctors to preserve the part of the body where the cancer started. It is not yet known whether radiation therapy with combination chemotherapy is more effective than radiation therapy alone in treating cancer of the oropharynx or hypopharynx that cannot be surgically removed.