What is the Benefit of Maintenance Therapy with Lenalidomide or Bortezomib after Autologous Stem Cell Transplantation in Multiple Myeloma and What is the Risk of Developing a Secondary Primary Malignancy?

An otherwise healthy 60-year-old male was diagnosed with stage II multiple myeloma by the International Staging System characterized by anemia, diffuse lytic bone lesions, IgG kappa paraproteinemia, 45% bone marrow plasmacytosis and the t(4;14) by FISH and conventional cytogenetics. The patient had a very good partial remission with initial induction therapy consisting of four 3-week cycles of bortezomib 1.3 mg/m2 IV on days 1, 4, 8, and 11 plus dexamethasone 40 mg days 1-4 (all cycles), followed by a cyclophosphamide and G-CSF mobilized melphalan 200 mg/m2 autologous stem cell transplantation (ASCT) and experienced minimal side effects. He is doing well 60 days post-ASCT and is in a near complete remission. His oncologist recommends maintenance therapy with lenalidomide or bortezomib, but the patient is concerned about the increased risk of developing a secondary malignancy (SM), and because he has had such an encouraging response to induction therapy, he wonders if he could remain off therapy.