A diagnosis of myeloma is made based on the presence of an increased number of plasma cells in the bone marrow and, in most cases, the presence of excess protein (M protein) in the blood or urine. At that point, patients are generally classified into categories based on their clinical and laboratory evaluation. Patients are also staged according to the severity of their disease based on a number of criteria.

Patients may be classified into one of three myeloma categories (MGUS, Asymptomatic, and Symptomatic) to help to determine treatment options. Patients in some categories do not have to receive treatment immediately, but may receive bisphosphonates if osteoporosis is present, or other supportive care for symptoms and complications. In these cases, postponing therapy may help avoid unnecessary side effects and the risk of complications associated with chemotherapy and may also delay development of resistance to chemotherapy. Knowing your classification is very important in deciding when it is appropriate to begin treatment. Participation in a clinical trial is also an option for many patients.

Patients with asymptomatic multiple myeloma have a monoclonal protein and slightly increased numbers of plasma cells in the bone marrow. They may have mild anemia and/or a few bone lesions, but do not exhibit the renal failure and frequent infections that characterize active multiple myeloma. In these patients the myeloma is static and may not progress for months or years. Asymptomatic multiple myeloma includes both Smoldering Multiple Myeloma (SMM) and Indolent Multiple Myeloma (IMM).

Patients who present with symptoms typically have a monoclonal protein and increased numbers of plasma cells in the bone marrow. They also have anemia, kidney failure, increased levels of calcium in the blood (hypercalcemia), or bone lesions. Patients with symptomatic myeloma require immediate treatment.

Proper staging of myeloma helps in determining prognosis and developing a treatment plan. The Durie-Salmon system has been the most widely used myeloma staging system since 1975 (see table). In this system, the clinical stage of disease (stage I, II, or III) is based on several measurements, including levels of M protein, the number of bone lesions, hemoglobin values, and serum calcium levels. In the Durie-Salmon system stages are further divided according to renal function as determined by serum creatinine levels (classified as A or B).

There is somewhat of an overlap between the various myeloma categories and stages. For example, both patients with smoldering myeloma and patients with Stage I disease do not require immediate treatment, and patients with Stage II and III disease have active, symptomatic myeloma. Increasingly, physicians are relying less on the Durie-Salmon staging system and more on biologically relevant markers as prognostic indicators when making treatment choices.

A new International Staging System (ISS) for myeloma has recently been proposed. This system appears to better discriminate between staging groups and can be widely used since it is based on easily measured serum levels of beta 2-microglobulin (ß2-M) and albumin.

The following table summarizes the staging criteria.