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Multiple myeloma
Multiple myeloma
Multiple myeloma is a cancer of the bone marrow. Normally, the bone marrow fills the inside of most bones and produces different types of blood cells. In Belgium, approximately 750 new cases of multiple myeloma are recorded each year, making it the second most common cancer of the bone marrow. This disease mainly affects people over the age of 60 and rarely occurs before the age of 40. It is neither contagious nor hereditary.
What is it?
Multiple myeloma is characterised by the uncontrolled multiplication of abnormal plasma cells (known as monoclonal plasma cells). Plasma cells belong to a family of white blood cells that produce antibodies (immunoglobulins) to help fight infections. Monoclonal plasma cells undergo changes that make their growth and behaviour abnormal, and they produce only one specific type of antibody, known as a monoclonal protein. This biological abnormality is detected by a test called serum protein electrophoresis, which analyses the proteins present in the blood. Electrophoresis is also performed on urine, as part of the monoclonal immunoglobulin may be detected there. To confirm the diagnosis with certainty, a bone marrow aspiration and/or biopsy is required. An analysis of the chromosomes of the myeloma plasma cells (called FISH) is performed to determine the severity of the disease. When the monoclonal protein is present but there is no excess of abnormal plasma cells, this is not called multiple myeloma but rather monoclonal gammopathy of undetermined significance (MGUS). This precancerous condition means that the cells are not yet cancerous, but that their risk of becoming cancerous is higher. Although the risk is very low (approximately 1% per year), MGUS may progress to multiple myeloma.
Symptoms
The clinical manifestations are varied and are classically grouped under the acronym “CRAB”:
- Calcium: excessively high calcium levels caused by bone decalcification in certain areas of the skeleton
- Renal impairment: multiple myeloma can weaken and damage the kidneys through several mechanisms (deposits of abnormal proteins in the kidneys, dehydration, toxicity from certain medicines, etc.)
- Anaemia, which may cause fatigue due to a lack of red blood cells
- “Bone”: malignant plasma cells promote the destruction of bone tissue, creating areas of weakness in the bone that may cause fractures. Pain is often the first symptom of the disease, occurring in the back, ribs, neck or pelvis. Sometimes, it appears suddenly as a result of a vertebral compression fracture or a fracture.
Blood tests, urine analyses and skeletal imaging are performed to detect these complications. Myeloma may also manifest itself through infections, particularly bacterial infections, due to weakened immune defences.
In approximately 20% of cases, the disease causes no symptoms and no physical symptoms are felt. An abnormal blood test result leads to investigations to determine whether the disease is present (this is referred to as asymptomatic multiple myeloma).
Treatment
Monitoring in the absence of symptoms:
Patients who do not present any detectable abnormalities are simply monitored medically, without starting treatment immediately. Treatment will begin when symptoms appear. Indeed, according to the results of various medical studies, there is no benefit to treatment when there is no organ involvement.
Treatment in the event of symptoms:
At present, treatments for myeloma cannot eradicate the disease permanently, so it cannot be described as cured. The aim of treatment is to control the disease (achieve remission), relieve symptoms and improve quality of life. There are many effective medicines for myeloma, and discoveries in recent years have led to considerable progress. Treatment protocols generally combine three medicines, including chemotherapy and/or targeted therapies, together with corticosteroids (Medrol, prednisone or dexamethasone). Autologous stem cell transplantation is reserved for patients under 65–70 years of age.
Radiotherapy may sometimes be offered in the event of bone lesions. During treatment, monitoring of the disease is based mainly on clinical examinations and monitoring of the monoclonal protein.