Multiple myeloma is a cancer of plasma cells, which are located within the bone marrow. Plasma cells are a part of the immune system, which fights infections. In multiple myeloma, abnormal plasma cells (myelomas) interfere with the growth of other blood cells, including red blood cells, white blood cells, and platelets. These abnormal plasma cells make it harder for the body to fight infections. In addition, as the plasma cells grow, they crowd out normal cells, leading to complications such as anemia and hemostatic abnormalities.
Multiple myeloma is not common, but it is serious. About 13,700 Americans learn each year that they have multiple myeloma. The disease accounts for about 1% of all cancers among Caucasians and 2% of those among African-Americans. Worldwide, about four people in every 100,000 develop the disease. The incidence seems to be increasing; however, this increase could be due to the fact that new techniques allow doctors to diagnose the disease more readily. Multiple myeloma is a disease of older people. Most people diagnosed with multiple myeloma are at least 60 years old.
The survival rate for multiple myeloma depends on the stage of disease at the time of diagnosis. The earlier the disease is caught, the better the prognosis. Patients receiving conventional chemotherapy typically survive from months to years, with an average survival rate of 2.5 to 3 years. Patients who receive bone marrow transplants have a better chance of prolonged survival.
Patients with myeloma often die of infections. Myeloma tumors weaken the body’s defenses against infection. As a result, respiratory and urinary tract infections are more frequent in patients with the disease. Patients with myeloma are 15 times more likely to get an infection than people in normal health.
Because there is usually no cure for multiple myeloma, treatment aims to control symptoms and complications, relieve pain, and stabilize bodily functions.
While doctors do not know what causes multiple myeloma, genetic abnormalities and exposure to environmental toxins may play a role. In some patients with myeloma, genetic abnormalities may contribute to tumor growth. Relatives of people with myeloma are at increased risk, as are people who work around insecticides and other chemicals.
Patients often have no symptoms for years, until the disease has progressed to an advanced stage.
- Stage I disease. This is the least serious type of multiple myeloma, during which patients have little or no bone damage, and have normal calcium levels in the blood. They are less likely to experience severe pain or kidney problems.
- Stage II disease. Patients with stage II disease have intermediate disease; that is, their symptoms are more pronounced than those in stage I but less severe than those in stage III.
- Stage III disease. In this most serious type of disease, large amounts of calcium and abnormal proteins are present in the blood, several areas of bone have been destroyed, and the hemoglobin level is low. Patients with stage III disease are likely to have severe bone pain and malfunctioning kidneys, as well as a greater chance of getting an infection.
Myeloma has symptoms similar to those of several other conditions Table 01. Symptoms can develop when multiple myeloma causes problems at the tumor sites and throughout the body. Patients often report back pain, fatigue, and lightheadedness when standing up. Because myeloma damages bones, pain is common at the tumor site. The disease can also cause impaired kidney function and decreased production of other necessary blood cells.
Most patients have initial symptoms of pain in the back and rib bones. Long-standing unexplained back or rib pain that does not respond to rest or anti-inflammatory drugs may indicate the need for additional testing.
Bones that are weakened by multiple myeloma are more easily broken, even without a serious fall or injury.
Patients may also have symptoms related to renal failure, anemia, increased calcium levels, or infection. Thirst and nausea can result from high calcium levels. Platelet abnormalities can cause patients to bleed easily. In addition, as M proteins interfere with normal clotting and tumor cells affect platelet production, little red spots may develop on the skin. M proteins can also cause painful nerve damage.
Table 1. Symptoms of Multiple Myeloma
Bone pain (usually involving the back and ribs) Recurrent bacterial infections Weakness, fatigue, lethargy Fever Bleeding Nausea Thirst Carpal tunnel syndrome Peripheral neuropathy
Patients with myeloma often develop anemia, a condition characterized by a reduction in the number of red blood cells.
Anemia occurs when tumor cells replace normal bone marrow tissue, and when kidney failure leads to a disappearance of or reduction in erythropoietin. About 80% of patients with multiple myeloma are already anemic when they learn that they have cancer.
Several factors can predispose a person to multiple myeloma. Multiple myeloma usually occurs in people over the age of 40. African-Americans are at greater risk than Caucasians, and men are at greater risk than women. Heredity may also play a role; having a sibling or parent with the disease may increase risk. People exposed to insecticides, herbicides, and other chemicals are thought to be at increased risk for multiple myeloma, but results of studies have been inconsistent. Farmers, leather workers, woodworkers, and petroleum industry workers may have a greater risk for the disease. Long-term exposure to radiation, such as in a nuclear power plant, may increase a person’s risk. Patients with immune abnormalities of the plasma cells (called monoclonal gammopathy of undetermined significance, or MGUS) or single tumors in the bone marrow and other tissues (solitary plasmacytomas) may eventually develop multiple myeloma (multiple myeloma will develop in about 20% of patients with MGUS). Herpes virus-8 (HHV8), which is associated with HIV-related Kaposi’s sarcoma, has been found in patients with multiple myeloma, but doctors do not yet know whether this finding is significant.
Multiple myeloma can be diagnosed by measuring an abnormal antibody called a monoclonal protein, which is often referred to as M or Bence-Jones protein, M component, or paraprotein. M protein is an abnormal protein produced in patients with multiple myeloma. M protein builds up in the blood and is eventually excreted into the urine. Patients are often diagnosed because the protein levels in their blood are too high, and this prompts more tests. If your doctor notices high blood protein levels along with high blood calcium levels, anemia and higher than normal levels of blood calcium, he or she should order more tests to diagnose multiple myeloma. These additional tests look for certain types of protein in the blood and in the urine.
The doctor will conduct a thorough physical and neurological examination to establish the cause of the symptoms and rule out other disorders. The doctor will feel along the back, ribs, long bones, and skull for any signs of masses, tenderness, soft spots, or depressions. The physician will also look for signs of bleeding or loss of sensation.
Laboratory tests, including standard blood tests and a urinalysis, will likely be ordered.
If the doctor suspects a plasma cell disease, serum protein electrophoresis will be done to check for M proteins. Your doctor will also order test for beta2 microglobulin levels, and serum viscosity, two tests that can be abnormal in someone with multiple myeloma. Serum protein electrophoresis is a blood test that can help detect abnormal plasma cells, and can help differentiate between multiple myeloma and other diseases with similar signs and symptoms.
If the standard tests are not conclusive, a doctor may order x-rays, magnetic resonance imaging (MRI), or a bone marrow aspiration and biopsy to rule out a plasma cell disorder. Bone lesions or bone weakening, often identifiable on x-rays, occur in 80% of patients with multiple myeloma. An MRI scan often helps to identify a tumor, the extent of damage to vertebrae, and the risk of spinal cord compression (which can cause pain or loss of limb function). During a bone marrow aspiration, the doctor uses a needle to remove a small amount of marrow, which is then biopsied to help pinpoint the diagnosis.
Doctors diagnose multiple myeloma based on results of the physical examination, the patient’s symptoms, and the results of diagnostic tests.
Doctors use a staging system to assess how far the disease has progressed. There are three stages of multiple myeloma. Because treatment is most effective in the early stages of the disease, it is important that the doctor determine the stage before a treatment is chosen. The Durie-Salmon system is the most common system used to evaluate patients with myeloma. This system examines:
- the amount of M protein in the blood or urine;
- the extent of bone damage (using x-rays); and
- the amount of hemoglobin, beta2-microglobulin (a protein produced by myeloma cells), and calcium in the blood.
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