One reason for the delay is that this cancer is rare, so physicians who’ve never seen it before may not recognize the symptoms. Multiple myeloma accounts for only 1.8 percent of all new cancer cases per year. According to the most recent estimates from the National Cancer Institute, a mere 6 or 7 people in 100,000 develop the disease annually. (1) Physicians may also fail to diagnose multiple myeloma because in its early stages the disease can be asymptomatic, a condition known as smoldering multiple myeloma. About one in five multiple myeloma patients find out they have this cancer before symptoms appear — when they go to the doctor’s office for a routine medical exam and lab tests reveal telltale changes in blood or urine. (2) Even when symptoms do appear they can be vague — weakness, fatigue — and resemble those of other health conditions or simply the signs of aging; most people diagnosed with multiple myeloma are over 65 (3). RELATED: Cancer News Digest: Latest Developments in Cancer Research and Treatment for June
Criteria for a Multiple Myeloma Diagnosis
A physician can make a multiple myeloma diagnosis based on a physical exam, a patient’s symptoms, and findings from lab work, biopsies, and imaging studies. The American Cancer Society summarizes the criteria for a multiple myeloma diagnosis with this checklist:
A tumor made up of plasma cells or at least 10 percent of these cells in the bone marrow and at least one of the following:High blood calcium levelPoor kidney functionLow red blood cell counts (anemia)Holes in the bonesIncrease in one type of light chain in the blood (a type of protein made by cancer cells)60 percent or more plasma cells in the bone marrow
Blood counts A test called the complete blood count (CBC) measures levels of red cells, white cells, and platelets in a blood sample. Myeloma cells can crowd out other cells in bone marrow, causing levels to drop.Blood chemistry tests These tests focus on creatinine (high levels indicate kidney problems common with multiple myeloma); the blood protein albumin (low levels of albumin but high levels of total blood protein are a red flag); and calcium (high levels may signify cancer). Doctors may also run additional tests to measure the enzyme lactate dehydrogenase (LDH) because elevated levels reveal that the disease has already reached an advanced stage. (4,5)Urine tests Myeloma cells produce something called a monoclonal protein — an abnormal type. This goes by a number of names, including M protein. The kidneys filter some of it out of the blood and pass it out of the body in urine.Quantitative immunoglobulins This test measures the levels of different kinds of antibodies in the blood. Multiple myeloma can raise or lower levels of certain antibodies. This is the umbrella term for a variety of tests that can detect monoclonal antibodies in a blood or urine sample.Serum-free light chains Antibodies are made up of “light” (short) and “heavy” (long) protein chains. This test looks for changes in light-chain levels, which can signify multiple myeloma.Beta-2 microglobulin This is another protein produced by myeloma cells; high levels suggest the cancer is at an advanced stage.
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Biopsies Focus on Bone and Marrow Samples
To make a multiple myeloma diagnosis, doctors study bone-marrow and bone samples in the lab and look for cancerous plasma cells. Getting those samples requires doing a biopsy or aspiration. Conducted either in a doctor’s office or a hospital with the patient under local anesthesia, the procedure involves inserting a needle and syringe into the pelvic bone to withdraw liquid bone marrow. The doctor also inserts a needle to take out a small bit of bone and marrow for analysis. Another type of diagnostic procedure called a needle biopsy uses a needle and a syringe to remove tissue from a tumor or a lymph node that shows signs of disease.
Imaging Tests Look for Cancer Damage and Hidden Tumors
Physicians use a variety of imaging tests to find evidence of multiple myeloma, track its progression, and assess the success of treatments.
X-rays Multiple myeloma can erode bone, creating holes or skeletal thinning (osteoporosis). X-rays can reveal this damage.CT scan Computed tomography (CT) imaging compiles a series of cross-sectional X-rays to create a detailed view of organs and bones, showing any damage.MRI (magnetic resonance imaging) scan These scans, which use radio waves and strong magnets, produce detailed images of soft tissues. MRIs can identify tumors that X-rays can’t and also produce images of bones and bone marrow that may reveal changes caused by multiple myeloma.PET (positron emission tomography) scan PET scans can also find tumors that X-rays have missed. This imaging method involves injecting patients with a form of radioactive sugar that cancer cells absorb in high amounts. (4)
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When the Diagnosis Isn’t Multiple Myeloma — Yet
Physicians sometimes diagnose a condition called monoclonal gammopathy of unknown significance, or MGUS, after blood samples taken during a routine medical checkup reveal unusually high levels of protein. For people with MGUS, abnormal plasma cells make up less than 10 percent of the cells in bone marrow. MGUS occurs in about 3 percent of people age 50 and older. (6) The condition is asymptomatic and doesn’t require treatment but puts doctors on alert, because over time MGUS can develop into multiple myeloma or another plasma cell or lymph disorder. A long-term study at the Mayo Clinic in Rochester, Minnesota, published in the New England Journal of Medicine in January 2018, followed more than 1,300 patients with MGUS over a median period of 34 years. The researchers found that MGUS progressed in 11 percent of patients — a rate that was almost seven times higher than in the general population. (6)
