What is Multiple Myeloma?

Core Conclusion

Multiple myeloma is a hematologic malignancy of bone marrow plasma cells characterized by CRAB features. Modern induction quadruplets and cellular immunotherapies now enable over 60% to 70% of patients to achieve durable remissions exceeding 10 years.

Detailed Points

• (1) What Plasma Cells Are and How They Become Cancerous: Normally, your bone marrow (the spongy center of your bones) makes healthy white blood cells called plasma cells. These cells are the "soldiers" of your immune system; they create protective proteins called antibodies (immunoglobulins) that help your body fight off infections and illnesses. However, sometimes an abnormal change (a genetic mutation) occurs that turns a healthy plasma cell into a cancerous myeloma cell. These myeloma cells begin to multiply out of control, crowding out the healthy blood cells you need. Instead of making helpful antibodies, they pump out massive amounts of a useless, abnormal antibody called a monoclonal (M) protein, which can build up in your body and cause damage.
• (2) MGUS, Smoldering Myeloma, and Active Myeloma: Myeloma does not appear overnight; it typically develops over a spectrum of stages:

  • MGUS (Monoclonal Gammopathy of Undetermined Significance): This is a benign, early precursor condition. It means you have a small amount of abnormal plasma cells in your bone marrow (<10%) and M protein in your blood (<3 g/dL), but absolutely no symptoms or organ damage. The risk of this turning into active myeloma is very low—only about 1% per year.
  • Smoldering Multiple Myeloma (SMM): This is an intermediate, pre-malignant stage. There are more plasma cells in your bone marrow (10% to 60%) and a higher level of M protein, but you still feel perfectly fine with no organ damage. The risk of progression to active myeloma is about 10% per year for the first 5 years.
  • Active Multiple Myeloma: This is the malignant stage requiring treatment. It means you have >= 10% cancerous plasma cells in your marrow and the disease has started causing physical symptoms or actual damage to your body's organs.
• (3) The CRAB Criteria: When doctors look for organ damage caused by active myeloma, they use the acronym CRAB to remember the four main signs:

  • C - Calcium elevation: Bone damage releases excess calcium into your blood (hypercalcemia), which can make you feel extremely thirsty, weak, and mentally confused.
  • R - Renal (kidney) failure: The heavy buildup of abnormal M proteins in your blood can overwork and damage your kidneys.
  • A - Anemia: Because myeloma cells crowd the bone marrow, your body cannot make enough red blood cells, leaving you feeling fatigued and weak.
  • B - Bone damage: Myeloma cells trigger your body to break down bone tissue faster than it can rebuild it, causing soft spots (lytic lesions), osteoporosis (thinning), pain, and a higher risk of fractures.
• (4) Why Myeloma is Treatable but Generally Incurable: It is hard to hear that a disease is "incurable," but please do not lose hope. Thanks to groundbreaking new therapies, the survival rates for myeloma have tripled. It is considered incurable because our current medications cannot completely eradicate every single microscopic cancer cell from the body. Because of this, the disease will usually return (relapse) after a period of improvement, and the cancer cells can eventually learn how to resist certain medications. However, because we now have so many different types of highly effective treatments, myeloma is increasingly being treated like a chronic medical condition that you can live with for many years, rather than an immediate terminal illness.

The above content is sourced from the following references

• NCCN Guidelines for Patients® Multiple Myeloma
• MULTIPLE MYELOMA PRECURSOR CONDITIONS
• MULTIPLE MYELOMA DISEASE OVERVIEW
• Patient Handbook
• International Myeloma Society/International Myeloma Working Group Consensus Recommendations on the Definition of High-Risk Multiple Myeloma