Myeloma is a cancer of the plasma cells in the bone marrow, the spongy tissue inside of bones. Plasma cells are a part of the body's immune system and help the body fight infections. If a plasma cell mutates (changes abnormally), it can grow uncontrollably and eventually form a tumor called a plasmacytoma. Solitary plasmacytoma is a mass of myeloma cells that is in only one site in the bone or other organs. Myeloma is often called multiple myeloma because more than 90% of people have cancer in multiple places in the bone marrow at the time it is diagnosed. Myeloma often causes structural bone damage resulting in painful fractures (broken bones).
Bones are continually shaped and maintained by bone cells called osteoclasts and osteoblasts. Osteoclasts destroy old bone, and osteoblasts build new bone. People with myeloma have abnormally high levels of osteoclasts, which mean that bone is destroyed faster than it can be replaced, potentially causing fractures, bone pain, osteoporosis (thinning of the bones), and hypercalcemia (high levels of calcium in the blood).
Bisphosphonates are medications that help strengthen the bone. Two bisphosphonates are approved by the U.S. Food and Drug Administration (FDA) for treating bone loss from multiple myeloma: pamidronate (Aredia) and zoledronic acid (Zometa). These drugs are given intravenously (IV) through a vein. The side effects may include flu-like symptoms, anemia, and joint and muscle pain. Uncommon but serious side effects have been identified in some patients, including:
- Kidney problems
- Acute kidney failure (when the kidneys suddenly stop working)
- Osteonecrosis (bone loss/weakening) of the jaw. Symptoms include pain, swelling, and infection of the jaw; loose teeth; drainage; and exposed bone.