What is it?
Multiple myeloma, often known simply as myeloma, is a type of cancer that affects immune cells called plasma cells. Cancer is caused by a mutation in the genetic material of the cell. While most mutations are harmless, some can, for example, make the cell unresponsive to any messages the rest of the body tries to send to it. This is what happens in cancer: cells start dividing uncontrollably, and eventually there’s enough of them to harm the rest of the body by stealing nutrients and taking space.
In the US, myeloma affects 6.1 per 100 000 people yearly, the average age of onset is 70, and the median survival is 4 years (although some might live for as long as 10 years after the onset of symptoms.)
Typical signs and symptoms of myeloma include heightened calcium levels, bone pain, anemia, and kidney failure.
What causes it?
The cause of myeloma is not known. Almost all cases are preceded with the presence of a myeloma-associated protein in the blood, but it it not understood why this condition sometimes develops to cancer. Obesity is also associated with a heightened risk of myeloma.
What happens during it?
The bone marrow inside the bones is where blood cells are generated. In myeloma, the genetic material of plasma cells has mutated. Plasma cells are white blood cells produced in the bone marrow, and one of their jobs is to produce specific molecules called antibodies that attach to invaders like bacteria and “mark” them for destruction. After mutating they start reproducing uncontrollably, and only produce one, useless antibody. These faulty cells spread throughout the body in the bloodstream, and accumulate inside the bone marrow disturbing its functions.
The myeloma cells start replacing healthy bone cells. This causes bone pain and heightened calcium levels as the bones are being dissolved. The kidney failure typical to myeloma comes about when the useless antibodies the plasma cells have started to produce accumulate inside various organs, including the kidneys. The amount of plasma cells inside the bone marrow inhibits red blood cell formation, which leads to anemia.
How can it be treated?
While myeloma remains incurable, a lot can be done to ease the symptoms. The main focus of treatment is to minimize the amount of mutated plasma cells in the body.
Initial treatment consists often of first killing off as many myeloma cells as possible using chemotherapy, and then transplanting healthy stem cells to the bone marrow. These stem cells are cells in the bone marrow that have not yet differentiated, i.e. have the potential to become any type of blood cell. First, stem cells are taken from the patient. Then, using chemotherapy (drugs that kill quickly dividing cells – this includes cancer cells, but also cells in the hair, for example), the myeloma cells are destroyed. The stem cells are then put back inside the patient and left to grow up to be healthy blood cells.
Unfortunately, the nature of myeloma means that a relapse always follows treatment. When this happens, the same method as before can be used or another one tried. As the disease advances, the focus shifts towards palliative care and making the patient as comfortable as possible.
Sources: https://en.wikipedia.org/wiki/Multiple_myeloma#Pathophysiology, https://en.wikipedia.org/wiki/Hematopoietic_stem_cell_transplantation, https://en.wikipedia.org/wiki/Monoclonal_gammopathy_of_undetermined_significance, https://en.wikipedia.org/wiki/Plasma_cell, http://www.medicalnewstoday.com/articles/161727.php#what_happens_in_multiple_myeloma, http://emedicine.medscape.com/article/204369-overview#a3