Despite the frequent advances in the field of cancer research and medicine, we don’t fully understand how cancer develops and what we know is still restricted to the genetics of many cancers regarding the gene disturbed that led to the uncontrolled proliferation of such cells. In multiple myeloma, there is no exception. The cancer that was first described in 1848 remains a serious problem which we still don’t know everything about.
What is multiple myeloma?
Multiple myeloma is a cancer of the bone marrow which resulted from several genetic defects that lead to increased division of a certain “line” of cells called plasma cells in the bone marrow. As is the case with many cancers, there is a premalignant stage, which means that such cancer doesn’t develop out of the blue but was preceded by a detectable stage in which it was not fully developed. This stage is called MGUS or Monoclonal Gammopathy of Undetermined Significance. The term looks intimidating, but its explanation is quite simple: monoclonal means that those cells resulted from a single “clone” or a mother cell. This is, in fact, the case with most blood cancers where they develop due to a single cell losing control of its proliferating machinery leading to uncontrolled division. The term gammopathy refers to the problem arising from plasma cells. Plasma cells are white blood cells of the B lymphocyte type after their activation. They are responsible for the production of antibodies which are proteins that are also termed “gamma globulins”.
During the stage of MGUS, mutations accumulate which is another key stage in the development of cancer, we need multiple mutations and alterations in DNA to develop the full blown uncontrolled disease because we have inherent defense mechanisms which protect us against such conditions. They include repair genes which repair any defects in DNA during cellular division or in response to external factors as well as “suicide” mechanisms that force the cells to kill and eat themselves from within in case of a fatal error in their genetic material.
After the MGUS stage comes the smoldering myeloma stage which is intermediate between MGUS and multiple myeloma. The differentiation between MGUS, smoldering myeloma and multiple myeloma stages is based on certain criteria including the level of a certain protein called the M protein secreted by the abnormal plasma cells of multiple myeloma.
Cells of multiple myeloma are subject to numerous factors that affect their growth and the disease’s severity. This usually has to do with what we call a “tumor microenvironment” which includes the multitude of chemical substances secreted from cancer cells that further affect their growth and the pattern of their division. This microenvironment is usually independent of the body’s control and therefore the growth of cancer is uncontrollable.