Multiple myeloma is a form of cancer that affects bone marrow, the spongy soft tissue that lies within the hollow centre of some bones.
The bone marrow contains stem cells that produce three types of blood cell: the red blood cells that transport oxygen around the body; the white blood cells involved in fighting infection; and platelets which are essential for blood clotting and healing processes.
These myeloma cells produce large amounts of an abnormal antibody (immunoglobulin) called paraprotein or M protein that is not effective at fighting infection and also interferes with the production of normal immunoglobulins.One form of differentiated B lymphocytes called the plasma cell is responsible for secreting large proportions of antibodies against invading bodies. In multiple myeloma, however, the plasma cells produced are abnormal and these are refereed to as myeloma cells.
The underlying cause of this disease process is still not clear among experts, although progress has been made in understanding the DNA changes that can cause plasma cells to become cancerous.
Some sections of our DNA (genes) are responsible for controlling the growth, division and death of cells. If these genes become altered or mutated, disordered cell regulation may lead to an abnormal, uncontrolled proliferation of cells which can cause cancer.
Myeloma cells have been found to have parts of chromosome 13 missing. These missing parts are called deletions and they appear to be linked to a myeloma that is more aggressive and resistant to treatment.
In around 50% of people with myeloma, the chromosomal change appears to be a translocation mutation, where one part of the chromosome in myeloma cells has become switched with part of another chromosome.