RATIONALE: Radioisotope therapy, such as iodine I 131 metaiodobenzylguanidine (MIBG), releases radiation that kills tumor cells. Drugs used in chemotherapy, such as topotecan, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Topotecan may also make tumor cells more sensitive to iodine I 131 MIBG. A peripheral stem cell transplant may be able to replace blood-forming cells that were destroyed by iodine I 131 MIBG and topotecan. This may allow more iodine I 131 MIBG and topotecan to be given so that more tumor cells are killed.