 RATIONALE: Drugs used in chemotherapy, such as melphalan, work in different ways to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. Radiolabeled monoclonal antibodies can find cancer cells and carry cancer-killing substances to them without harming normal cells. A stem cell transplant using stem cells from the patient may be able to replace blood-forming cells that were destroyed by the chemotherapy and radiolabeled monoclonal antibody. 