Multiple myeloma is a relatively rare blood cancer, accounting for 1 percent of all cancer diagnoses.
What is multiple myeloma?
Multiple myeloma is a type of cancer that develops in plasma cells within the bone marrow. As cancerous plasma cells accumulate in the marrow, they crowd out healthy blood cells. This may cause symptoms such as infection, anemia, bruising and bleeding.
Myeloma cells also increase the activity of cells called osteoclasts (which break down bone) and decrease the activity of osteoblasts (which form new bone), causing the bones to dissolve at a faster rate than they’re formed. This may damage and weaken the bones, causing pain, lesions and other symptoms.
Symptoms of multiple myeloma
Initial multiple myeloma symptoms may be mild or even undetectable. A precursor stage is known as smoldering multiple myeloma (SMM). It may continue to worsen until the cancer is discovered. Though SMM is typically slow-growing, patients may need frequent testing to monitor its progression.
As abnormal plasma cells grow, divide and take over the bone marrow, the likelihood of developing symptoms increases. Not only do abnormal plasma cells crowd out healthy bone marrow cells, damaging the bone, but they also release antibodies, M protein and other proteins into the blood, thickening it.
Many people have symptoms of bone damage, bone loss and bone fracture. Multiple myeloma may also lead to kidney damage and injury and dysregulated blood levels of antibodies and proteins.
Multiple myeloma symptoms vary for each person. Some common signs include:
- Pain in the bones of the back or ribs
- Bones that fracture easily
- Fatigue and weakness
- Shortness of breath
- Dizziness
- Unexplained weight loss
- Frequent infections and fevers
- Frequent need to urinate and extreme thirst
The bone damage associated with multiple myeloma occurs mostly in the rib cage, spine and pelvis, increasing the risk of spinal cord compression, which causes pain, numbness or weakness in the limbs and requires immediate treatment. It may come on gradually or suddenly.
CRAB: Common signs of multiple myeloma
Patients may hear the term “CRAB” to describe the most common signs of multiple myeloma. This acronym stands for calcium levels (C), renal failure R), anemia (A) and bone pain (B), with details as follows.
Calcium levels in the blood are elevated: Myeloma may weaken and degrade bones, leading to calcium entering the bloodstream (a condition known as hypercalcemia). This condition may lead to symptoms including nausea, thirst, reduced appetite, confusion or constipation.
Renal failure: Renal failure describes lack of function in the kidneys. Because myeloma cells release high levels of proteins, kidney damage may result.
Anemia: If myeloma cells come into contact with healthy bone marrow (where blood cells develop), the body may not make enough red blood cells, leading to anemia. Anemia may cause fatigue, weakness, fast heartbeat, shortness of breath and other symptoms.
Bone pain: Because myeloma may damage the bones, pain may result, particularly in the spine and ribs.
Related conditions associated with multiple myeloma
As multiple myeloma progresses, other conditions develop. Three significant conditions are associated with multiple myeloma: amyloidosis, hypercalcemia and anemia.
A major co-occurring condition with multiple myeloma is amyloidosis, a buildup of proteins in the body that injures organs, stopping them from functioning normally. In addition to the primary symptoms of multiple myeloma, amyloidosis may cause:
- Purple spots on skin
- Swollen tongue or other issues with swelling
- Numb or tingly feeling in limbs, especially the feet and legs
- Painful joints
- Diarrhea, clay-colored stools or other digestive issues
Damage to the bones from multiple myeloma may allow too much calcium to be released into the blood. This causes hypercalcemia, a condition that may cause symptoms including:
- Nausea, vomiting or loss of appetite
- Constipation and other digestive issues
- Twitching of muscles or restless feeling
Hypercalcemia, amyloidosis and the excess of M protein and antibodies released by growing plasma cell tumors may damage organs, including the kidneys, nerves, heart, muscles and digestive tract. Multiple myeloma may lead to kidney failure and damaged peripheral nerves in the limbs. Symptoms of kidney failure include:
- High blood pressure
- Fluid retention
- Swelling of the legs, feet or ankles
- Headaches
- Itching
- Muscle cramps
- Stiffness or fluid in joints
Excess B-cells in the bone marrow may crowd out other blood stem cells that make red blood cells, causing anemia, or a low red blood cell count. Red blood cells transport oxygen from the lungs to all organs of the body. Anemia causes several symptoms, including:
- Easy bruising or bleeding
- Cognitive issues, such as trouble thinking or getting easily confused
- Feeling that limbs are weak or easily fatigued
Anyone experiencing these symptoms should see a doctor for an evaluation. If multiple myeloma is diagnosed, the care team will design a personalized treatment plan, taking into consideration the type and stage.
