DISEASE CHARACTERISTICS: Newly diagnosed multiple myeloma (diagnosis within 12 months of study) and scheduled to undergo autologous peripheral blood stem cell transplantation Prior diagnosis of monoclonal gammopathy of undetermined significance (MGUS) or smoldering myeloma (SMM) allowed if the criteria for diagnosis of multiple myeloma was met within 12 months of study Serum or urinary M-protein confirmation of diagnosis (IgA, IgD, IgG, IgE, or light chain proteins) At least 10% plasma cells in bone marrow Must have received induction therapy without disease progression or relapse after initial response Prior induction therapy must have been completed no more than 6 months before stem cell collection and no more than 9 months before transplantation Must have undergone stem cell mobilization with cyclophosphamide IV and filgrastim (G-CSF) The following diagnoses are excluded: Non-secretory multiple myeloma IgM myeloma Solitary bone or extramedullary plasmacytoma Symptomatic MGUS or SMM Symptomatic indolent multiple myeloma