Myeloma and Related Conditions

Multiple myeloma (MM) is a malignancy of clonal plasma cells with a wide spectrum of plasma cell disorders. The classification of plasma cell neoplasm requires integration of clinical, laboratory, and pathologic features. It is important to correctly identify patients with symptomatic myeloma in order to initiate appropriate treatment before any further end-organ damage. The myeloma defining events described in the diagnostic criteria include CRAB features (hyperCalcemia, Renal insufficiency, Anemia, Bone lesions) and biomarkers of malignancy (SLiM features [Sixty percent clonal bone marrow plasma cells, serum-free Light-chain ratio; Magnetic resonance focal]). In addition to staging, the International Staging System, along with fluorescence in situ hybridization/cytogenetics, can also be used for risk stratification. Risk stratification allows long-term planning as well as prognostication. Gene expression profile studies in MM have revealed not only important aspects of tumor biology but may also have a role in the clinical setting for prognostication. Clinical implementation of this tool, however, is still currently limited as there are still many unanswered questions. Although initial treatment is not affected by risk category, our understanding of MM pathobiology has translated to development of novel therapeutic agents that can be used in appropriate stages throughout the disease course. Assessment of minimal residual disease (MRD) is also an important aspect of management—it serves as an indicator of treatment efficacy, and MRD negativity is associated with a longer progression-free and overall survival. As a result of these advances, the median survival of MM patients has increased from 3 years to more than 7 to 8 years and, in a number of individuals, it has become a chronic disease with a curative outcome.