Multiple Myeloma

Overview

Multiple myeloma is a blood cancer that develops when healthy plasma cells in the bone marrow mutate and multiply uncontrollably. Myeloma cells overcrowd the bone marrow and suppress the growth of healthy cells that produce blood. This unusual cell growth can affect the body’s ability to fight infection and can result in anemia, bone damage and excessive bleeding from cuts. Although few patients with myeloma are currently cured, many treatments are available to manage the disease. Advances made in the development of treatments have made it possible for people with multiple myeloma to live healthy and active lives.

Understanding Bone Marrow and Cells

To fully understand multiple myeloma, it’s important to first gain a general knowledge of bone marrow and blood cells.

  • Antibodies are proteins created from plasma cells as a reaction to foreign substances, such as bacteria, in the body.
  • Bone marrow is the soft, spongy center of some bones that contains immature blood stem cells, more mature blood-forming cells, fat cells and tissues that support cell growth. The immature blood stem cells, known as hematopoietic stem cells, develop into several types of blood cells, including white blood cells, red blood cells and platelets (see Figure 1).
  • Lymphocytes are the primary cells in lymphoid tissue, which is a major part of the immune system. These cells develop from lymphoblasts (immature cells found in bone marrow) into mature, infection-fighting cells. Subtypes of these cells include B-lymphocytes and T-lymphocytes.
  • Plasma cells develop from B-lymphocytes and produce antibodies to help fight germs and viruses, and stop infection and disease. Plasma cells are primarily found in the bone marrow.

                                                      Figure 1.

 

The immune system is a network of cells, organs and tissues that work together to defend your body against germs and infection. Plasma cells play an important part in this system. When plasma cells identify a threat to the body, they create different types of antibodies. For example, if you catch a cold, plasma cells create antibodies that target the specific germs that caused your cold. Likewise, if you have seasonal allergies to pollen, the allergic reaction that you experience is the result of your plasma cells creating a new set of antibodies to attack the pollen.

Abnormal, cancerous plasma cells are called myeloma cells, and, like normal plasma cells, myeloma cells make antibodies. There are many types of plasma cells that create different antibodies, but myeloma cells are all the same and produce too much of the same antibody. These antibodies are called monoclonal antibody proteins, or M proteins. M proteins accumulate in the blood and urine and can lead to damage of the kidneys or other organs.

                  Figure 2.

 

In people with multiple myeloma, the myeloma cells multiply uncontrollably (see Figure 2 above). Over time, the myeloma cells accumulate in bone marrow, solid parts of bone and, occasionally, in other organs. This accumulation of myeloma cells usually occurs in multiple areas of the bones in the body, giving the disease its name, “multiple myeloma.” When the cells collect in bone marrow, they slow down the growth of healthy white blood cells, red blood cells and platelets (see Figure 3, below). These cells collect in solid bone, causing holes called lytic lesions. The majority of people with multiple myeloma have these lesions when their disease is diagnosed.

                  Figure 3.

Contributing Factors

Although the exact cause of multiple myeloma is unknown, scientists continue to learn more about the development of the disease. Research suggests that your risk for multiple myeloma can increase because of some factors, including a family history of multiple myeloma, exposure to certain chemicals and radiation, and obesity. Scientists have discovered patterns between certain risk factors and the development of multiple myeloma, but there is no solid evidence that these risk factors cause the disease.

Age, gender and race also play a role. Multiple myeloma is far more common in adults older than 60 than in adults younger than 40, is more common in men than in women, and develops more often in African-American individuals than in Caucasian individuals.

Studies have also found that most people with multiple myeloma have identifiable genetic mutations in their plasma cells. For example, in about half of people with the disease, part of one chromosome in the myeloma cells has switched with part of another chromosome. Another common finding is that certain parts of one chromosome – chromosome 13 – are missing from myeloma cells. Research is ongoing to determine the precise role these changes in DNA play in the cause of multiple myeloma.

The only two known precursors to multiple myeloma are monoclonal gammopathy of undetermined significance (MGUS) and smoldering myeloma. MGUS is a condition that occurs when abnormal plasma cells produce many copies of an identical antibody. These plasma cells do not usually form a mass or tumor, and MGUS will not usually affect a person’s health. Most cases of multiple myeloma are preceded by MGUS, but it is unknown whether MGUS is always present before diagnosis. At this time, no treatments exist for MGUS, and no preventive treatments can keep MGUS from progressing to myeloma. People with MGUS should not be treated until multiple myeloma is present. Smoldering myeloma, also called asymptomatic multiple myeloma, is an early stage of myeloma. Preventive treatments to delay smoldering myeloma from progressing to multiple myeloma are being studied in clinical trials.

Common Signs

Multiple myeloma does not typically present any symptoms in its early stages, and it is often discovered by a doctor unintentionally, for example, in the results of a blood or urine test done during an annual check-up. Some people may have symptoms that are vague or that may seem related to other conditions. If this is the case, doctors may simply monitor the condition until specific signs appear. This type of monitoring is commonly called watchful waiting. Signs of the disease vary among people and depend on the number of myeloma cells in the body and in the area they collect. The most common signs relate to bone and calcium problems, low blood counts and kidney damage (see Staging).

Multiple myeloma cells tend to interfere with bone growth, causing the bones to break down quickly without replenishing themselves. This causes bone weakness and can contribute to an increased amount of calcium in the blood, known as hypercalcemia. The overproduction of abnormal plasma cells also crowds out healthy blood-forming cells and may cause anemia (shortage of red blood cells), leukopenia (shortage of normal white blood cells) and thrombocytopenia (low platelets). These can all result in side effects such as fatigue, increased bleeding and bruising, and an inability to properly fight infections.

The crowding of normal cells may also interrupt the normal production of antibodies, which are created by normal plasma cells in response to harmful infections. However, multiple myeloma cells create M proteins, which continue to reproduce and accumulate (see Figure 4). This buildup not only affects the body’s ability to fight infections but can also lead to kidney damage and, possibly, kidney failure.

                   Figure 4.

Additional Resources

 

Next
   

 



Register Now! Sign Up For Our Free E-Newletter!

Read Inspiring Cancer Survivor Stories

Order Your Guides Here