Multiple Myeloma: bone or B cell cancer?

Human bone marrow.

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MM or multiple myeloma is actually a cancer of the mature B cell in the body but as it is targeted to the bone marrow and produces fractures and small pockets of hollowed out bone, many people tend to think of it as a bone cancer.  MM is incurable currently and many treatments are available now to help prolong the life for those with this cancer.

MM has a frequency of about 1 to 4 in 100, 000 in whites but it is as high as almost 10 per 100,000 in African Americans and is the tenth largest cancer killer among that group of individuals.  Usually, the cancer strikes those who are older at 65-70 years of age, but it can occur in younger patients as well.  Unfortunately, there are no easy to detect early signs or symptoms of the disease and by the time bone pain shows up the disease is already at an advanced stage.

The cancer affects cells known as plasma cells or B cells that produce antibodies in large numbers.  They reside in the bone marrow and when they become cancerous they divide quickly, produce lots of a single kind of antibody (that causes lots of problems for the kidney and can also suppress the immune system over time).  However, it can also result in bone pain by the following process.  The cancerous cells stay in the bone marrow where they divide rapidly and stick to the walls of the bone in the marrow area.  They produce all sorts of proteins that make them grow even faster and avoid immune detection and avoid death.  They start to produce products that break down the bone in the localized area and prevent the normal cells in the area from building the bone back up.  So, the results of this is that the cells burrow and make small holes along various bones in the body.  X-ray can pick up these small pockets of hollowed out bone.  A result is that the bones can become fractured easily and patients can get a type of osteoporosis. This of course results in pain over time, but again when the patient visits the doctor the cancer has already reached an advanced stage.  One other symptom in many patients is that they may become anemic (low blood counts) and that is due to the large number of cancerous B cells in the bone marrow that acts to suppress the stem cells from sending the precursors of blood cells into the body.

Anyhow, when the patient goes to the doctor he or she must treat the many symptoms of the disease in addition to the cancer itself.  The cancer itself is a blood cancer and can not be simply removed by surgery.  Thus a number of drugs are used to treat the disease and will not be mentioned here specifically.  In general, MM is treated with chemotherapy (drugs that try to kill the cancer cell itself or all rapidly dividing cells).  There are also drugs given to help boost the production of normal bone marrow cells and those that help to heal the bone.

As this is an incurable cancer overall and some people live with the disease after treatment longer than others, lots of research is being done to try to see if scientists can identify those who will respond well to treatment and those who will not.  For example, using genetic screening on a large-scale we now know that some patients with certain genetic mutations (or sometimes the lack of certain mutations) will have a worse prognosis that others who do not carry that mutation.  Research is also being undertaken for the search for new drugs and the search for potential immunotherapy that might one day help.

So, to make a long story short….MM is a devastating disease that affects both the bones and the cells of the immune system.  However, it is a disease of the B cell primarily and is usually detected late in older patients.  There is no cure but people can live up to seven years after detection of the disease if treatment goes well.

Thank you for reading this…and do let me know if you have any questions or comments about MM or other cancers.  Also, feel free to go to Cancer made Simple for other information.

Dr. C

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Cancer Stem cells

Stem cell diagram illustrates a human fetus st...

Image via Wikipedia

So, someone asked me the other day to explain cancer stem cells to him and I realized this is something I have never written about.  It happens to be a relatively new concept but an important one so I will quickly talk about what they are,

All cells in the body came from originally a very small set of cells at one time.  All of our blood cells for example came from one set of cells called the blood stem cells at one point (the technical name is hematopoietic stem cell).  We call the different kind of stem cells that give rise to different kinds of general cell types as lineage derived stem cells.   Fat tissue, cells that line the intestine, nerve cells, etc. all come from different stem cells at the beginning.

So, one property of stem cells that is that they can give rise to a whole series of like cells (e.g nervous tissue cells or fat tissue cells).  In order for this to happen the original stem cells must be able to do this without dying and without itself changing.  This is NOT a property of most cells….most cells die after some rounds of division and they change as they mature.  Stem cells do not share this property and can in fact multiply for ever potentially.

So, most cancer cells develop from very specific tissues like the cells of the eye, or cells from the nervous tissue and so on and so forth.  In some cases and in some cancers, scientists have found that cancers develop from the stem cells themselves….either very early stem cells (very rare) or mare differentiated stem cells (more common).

Either way, there is a big difference between a cancer from a non stem cell to that of a cancer from a stem cells.  Or, if a single cancer has both stem cells and non stem cells this also poses a unique problem.  To make a long story short, cancer stem cells are very difficult to treat.  They are usually very resistant to treatment and don’t respond well to things like chemotherapy, etc.  Also, when you kill off cancer cells and the cancer seems to go away, if the cancer remains in the cancer stem cells, then they can divide and create more cancer cells.  So, even if you think you have gotten rid of the cancer, it is still there but in small amounts as a stem cell.  We do not know how frequent this is but it has been seen in breast cancer and in a few other cancers.  It is still a bit controversial so we do not know anything yet about true clinical experience with these.

Thanks and let me know if you want more information on this as I only just scratched the surface.

Dr. C please visit Cancer Made Simple!@