Conventional and molecular cytogenetics in plasma cell neoplasms

Plasma cell neoplasms are clinically and pathologically heterogeneous disorders, due in part to the complexity of their underlying genetic abnormalities. These neoplasms have been studied since the early days of cancer cytogenetics, and as genetic techniques have advanced, so has understanding of the biology of myeloma and its precursor lesions, monoclonal gammopathy of uncertain significance (MGUS) and smoldering myeloma (SMM). Evaluation of patients with plasma cell neoplasms now involves multiple genetic tests, the most widely used of which are G-banding and fluorescence in situ hybridization (FISH). Newer technologies, such as oligonucleotide- and single nucleotide polymorphism (SNP)-based microarray testing and next-generation sequencing, are becoming more widely used and are giving genomic testing an even greater role in risk stratification. A primary goal of genetic testing in plasma cell neoplasms is to identify patients with both high-risk and standard-risk disease: the former, to ensure these patients receive sufficient therapy and/or stem cell transplantation, and the latter, to spare these individuals unnecessarily toxic therapy. Thus, identification of the genetic abnormalities of a patient's disease is critical to providing individualized targeted therapy.