RATIONALE: Monoclonal antibodies, such as rituximab, can block cancer cell growth in different ways. Some block the ability of cancer cells to grow and spread. Others find cancer cells and help kill them or carry cancer cell-killing substances to them. Drugs used in chemotherapy, such as ifosfamide, carboplatin, and etoposide, work in different ways to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. Se-methyl-seleno-l-cysteine may help reduce the side effects of chemotherapy.