Disease overview: Multiple myeloma is malignant plasma-cell disorder that accounts for 10% of all hematologic malignancies. Diagnosis: The diagnosis requires (1) 10% or more clonal plasma cells on bone marrow examination or a biopsy-proven plasmacytoma plus (2) evidence of end-organ damage felt to be related to the underlying plasma cell disorder. Risk stratification: Patients with 17p deletion, t(4;14), t(14;16), t(14;20), and karyotypic deletion 13 or hypodiploidy are considered to have high-risk myeloma. All others are considered to have standard-risk disease. Risk-adapted therapy: Standard-risk patients are treated with nonalkylator-based therapy such as lenalidomide plus low-dose dexamethasone (Rd) followed by autologous stem-cell transplantation (ASCT). If patients are tolerating the induction regimen treatment well, an alternative strategy is to continue initial therapy after stem-cell collection, reserving ASCT for first relapse. High-risk patients are treated with a bortezomib-based induction followed by ASCT and then bortezomib-based maintenance. Patients not eligible for ASCT can be treated with Rd for standard risk disease or a bortezomib-based regimen if high-risk features are present. To reduce toxicity, when using bortezomib, the once-weekly dose is preferred; similarly, when using dexamethasone, the low-dose approach (40 mg once a week) is preferred, unless there is a need for rapid disease control.
Disease OverviewMultiple myeloma accounts for 1% of all cancers and 10% of all hematologic malignancies [1,2]. Each year, over 20,000 new cases are diagnosed in the United States [3]. Contrary to the popular belief, the annual age-adjusted incidence in the United States has remained stable for decades at approximately four per 100,000 [4]. Multiple myeloma is slightly more common in men than in women and is twice as common in African-Americans compared to Caucasians [5]. The median age of patients at the time of diagnosis is about 65 years [6].Unlike other malignancies that metastasize to bone, the osteolytic bone lesions in myeloma exhibit no new bone formation. Bone disease is the main cause of morbidity and can be detected on routine skeletal radiographs, magnetic resonance imaging (MRI), or fluorodeoxyglucose positron emission tomography/computed tomographic scans (PET-CT) [7]. True extramedullary lesions and extramedullary expansion of bone lesions can also occur. Other major clinical manifestations are anemia, hypercalcemia, renal failure, and an increased risk of infections.It is now known clear that almost all patients with myeloma evolve from an asymptomatic premalignant stage termed monoclonal gammopathy of undetermined significance (MGUS) [8,9]. MGUS is present in over 3% of the population above the age of 50 and progresses to myeloma or related malignancy a rate of 1% per year [10,11]. In some patients, an intermediate asymptomatic but more advanced premalignant stage referred to as smoldering multiple myeloma (SMM) can be recognized clinically [12,13]. SMM progressed to myeloma at a rate...