Multiple Myeloma and Related Disorders
Summary of Key Points
Multiple Myeloma
• Multiple myeloma accounts for approximately 10% of hematologic malignancies.
• An estimated 22,000 new cases occurred in the United States in 2012.
• Almost all cases are thought to evolve from an asymptomatic premalignant stage termed monoclonal gammopathy of undetermined significance (MGUS).
Diagnosis
• The most common presenting symptoms are fatigue and bone pain.
• Osteolytic bone lesions are the hallmark of the disease.
• Hypercalcemia is found in one fourth of patients; the serum creatinine level is elevated in almost one half of patients.
• Diagnosis requires 10% or more clonal plasma cells in the bone marrow and/or a biopsy-proven plasmacytoma, monoclonal (M) protein in the serum and/or urine (except in patients with true nonsecretory myeloma), and evidence of end organ damage (hypercalcemia, renal insufficiency, anemia, or bone lesions) attributable to the underlying plasma cell disorder. Patients with 60% or more clonal plasma cells in the bone marrow are considered to have multiple myeloma even in the absence of end organ damage.
• M proteins can be detected by serum protein electrophoresis (SPEP) and immunofixation in 93% of patients; addition of urine protein electrophoresis (UPEP) and urine immunofixation or the serum free light chain (FLC) assay will increase sensitivity to 97% or higher.
Prognosis
• The International Staging System (ISS) divides patients into three distinct stages and prognostic groups based on the β2-microglobulin and albumin levels in the serum.
• High-risk myeloma is defined as the presence of any one or more of the following: deletion 17p, immunoglobulin heavy-chain (IgH) translocations t(14;16) or t(14;20), plasma cell leukemia, increased lactate dehydrogenase level, and high-risk signature on gene expression profiling studies. The translocation t(4;14) is considered intermediate risk, and all others indicate standard risk.
Treatment
• Newly diagnosed patients are categorized as having standard-, intermediate-, and high-risk myeloma based on specific prognostic factors.
• Initial therapy for patients with standard-risk disease is with regimens such as lenalidomide–low-dose dexamethasone (Rd) or bortezomib-cyclophosphamide-dexamethasone (VCD). A bortezomib-containing regimen is preferred as initial therapy for patients with intermediate- and high-risk myeloma.
• After 4 months of initial therapy, patients eligible for transplantation can pursue early or delayed autologous stem cell transplantation (ASCT). If early ASCT is used, a second ASCT is considered in patients who do not achieve a very good partial response or better with the first ASCT. If transplant is delayed, patients will continue on the induction chemotherapy drugs at lower doses until plateau or progression occurs.
• Options for relapsed disease include thalidomide, lenalidomide, bortezomib, alkylating agents, anthracyclines, and corticosteroids alone or in combination.
Monoclonal Gammopathy of Undetermined Significance (MGUS)
• MGUS is an asymptomatic, premalignant, clonal plasma cell proliferative disorder defined by the presence of a serum M protein level less than 3 g/dL, bone marrow plasma cells less than 10%, and absence of anemia, hypercalcemia, lytic bone lesions, or renal failure that can be attributed to the plasma cell proliferative disorder.
• MGUS is found in approximately 3% of the general population 50 years of age and older.
