Multiple Myeloma is an uncontrolled growth of malignant plasma cells in the bone marrow. Bone marrow is the spongy, red tissue in the interior of bones that contains stem cells from which blood cells evolve. Normal plasma cells are also present in the bone marrow. Plasma cells are white blood cells that make antibodies. Another word for the malignant plasma cells is myeloma cells. The myeloma cells can be in several (different) places in the bone marrow, hence the name multiple myeloma.Multiple myeloma used to be called Kahler’s disease. Otto Kahler (1849 – 1893) was the Austrian internist who first described the disease. In the Netherlands the term Kahler is still used.
How often does multiple myeloma occur?
According to the World Cancer Research Fund International, an estimated 114,000 people around the world are diagnosed with multiple myeloma annually, and the disease represents 0.8% of all cancers globally. In men, the disease is slightly more common and the average age is 70 years. One third of the patients is older than 75 years. A very small portion of the patients are younger than 45 years.
What is multiple myeloma
There are different types of white blood cells. These all play a role in the immune defense system. One type of white blood cell is called lymphocyte and certain lymphocytes can develop into plasma cells in the lymph nodes. A plasma cell settles in the bone marrow after maturation. Plasma cells can also occur outside the bone marrow; for example in the intestines, the respiratory tract and the lymph nodes. Plasma cells make antibodies and antibodies protect the body against infection with viruses and bacteria. Antibodies are proteins and each plasma cell can only produce one type of antibody.
Uncontrolled growth & M-protein
In the plasma cell’s DNA, errors can occur during cell division. These changes in the genetic material are usually restored. Sometimes there is no recovery and cells can become malignant, starting to divide uncontrollably. Normally the number of plasma cells is less than 5% of the total number of cells in the bone marrow. In multiple myeloma, the number of plasma cells is often more than 5% up till even 90%. Malignant plasma cells can spread through the blood. Multiple myeloma is therefore usually found in several places in the bone marrow.
All the malignant plasma cells are derived from the same original and are therefore clones. Since plasma cells produce one type of antibody, you get a large amount of one type of antibody in multiple myeloma. This is called a monoclonal antibody or M-protein. The M-protein can be measured in blood and sometimes urine.