RATIONALE: Drugs used in chemotherapy, such as topotecan and 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. Internal radiation uses radioactive material placed directly into or near a tumor to kill tumor cells. Topotecan and cisplatin may make tumor cells more sensitive to radiation therapy. Giving topotecan and cisplatin together with radiation therapy may kill more tumor cells.