There has been remarkable progress made in the diagnosis and treatment of multiple myeloma (MM). The median survival of the disease has doubled as a result of several new active drugs. These advances have necessitated a revision of the disease definition and staging of MM. Until recently, MM was defined by the presence of end-organ damage, specifically hypercalcemia, renal failure, anaemia, and bone lesions (CRAB features) that can be attributed to the clonal process. In 2014, the International Myeloma Working Group (IMWG) updated the diagnostic criteria for MM to add three specific biomarkers that can be used to diagnose the disease in patients who did not have CRAB features: clonal bone marrow plasma cells greater than or equal to 60%, serum free light chain (FLC) ratio greater than or equal to 100 provided involved FLC level is 100 mg/l or higher, or more than one focal lesion on MRI. In addition, the definition was revised to allow CT and PET-CT to diagnose MM bone disease.

With the introduction of immunomodulatory agents (IMiDs) and proteasome inhibitors (PIs), major improvements have been achieved in the treatment and outcome of MM. Different treatment combinations are now in use and newer therapies are being developed. However, nearly all MM patients ultimately relapse, even those who experience a complete response to initial therapy. Management of the relapsed disease remains a critical aspect of MM care and an important area of ongoing research. The aim of this review is to summarise the current methods of diagnosis and treatment of MM.