Multiple myeloma

Multiple myeloma (MM), also known as plasma cell myeloma and simply myeloma, is a cancer of plasma cells, a type of white blood cell that normally produces antibodies. Often, no symptoms are noticed initially. As it progresses, bone pain, anemia, renal insufficiency, and infections may occur. Complications may include hypercalcemia and amyloidosis.

The cause of multiple myeloma is unknown. Risk factors include obesity, radiation exposure, family history, age and certain chemicals. There is an increased risk of multiple myeloma in certain occupations, due to occupational exposure to aromatic hydrocarbon solvents. Multiple myeloma is the result of a multi-step malignant transformation, and almost universally originates from the pre-malignant stage monoclonal gammopathy of undetermined significance (MGUS). As MGUS evolves into MM, another pre-stage of the disease is reached, known as smoldering myeloma (SMM).

In MM, the abnormal plasma cells produce abnormal antibodies, which can cause kidney problems and overly thick blood. The plasma cells can also form a mass in the bone marrow or soft tissue. When one tumor is present, it is called a plasmacytoma; more than one is called multiple myeloma. Multiple myeloma is diagnosed based on blood or urine tests finding abnormal antibody proteins (often using electrophoretic techniques revealing the presence of a monoclonal spike in the results, termed an m-spike), bone marrow biopsy finding cancerous plasma cells, and medical imaging finding bone lesions. Another common finding is high blood calcium levels.

Multiple myeloma is considered treatable, but generally incurable. Remissions may be brought about with steroids, chemotherapy, targeted therapy, and stem cell transplant. Bisphosphonates and radiation therapy are sometimes used to reduce pain from bone lesions. New approaches utilizing CAR-T cell therapy have been included in the treatment regimens.

Globally, about 175,000 people were diagnosed with the disease in 2020, while about 117,000 people died from the disease that year. In the U.S., forecasts suggest about 36,000 people will be diagnosed with the disease in 2026, and about 10,850 people will die from the disease that year. In 2020, an estimated 170,405 people were living with myeloma in the U.S. Based on data from people diagnosed with the disease in the United States between 2016 and 2022, about 64% lived five years or more post-diagnosis.

The disease usually occurs around the age of 60. It is uncommon before the age of 40. The word myeloma is from Greek myelo- 'marrow' and -oma 'tumor'.