Multiple myeloma is a cancer caused by abnormal growth of a type of cell located in the bone marrow, the plasma cells. These cells, which are derived from B lymphocytes, produce immunoglobulins, the proteins necessary to defend the body against infection. Uncontrolled growth of these cells causes infection, anaemia and other complications.
This disease affects 4 out of every 100,000 individuals per year. The average age of patients when the disease appears is around 65.
The main characteristics of myeloma are: changes in normal bone marrow functions, which result in anaemia and/or low leukocyte or platelet counts; destruction and invasion of the bone that surrounds the bone marrow cavity; production of monoclonal protein (M-protein) by the myeloma cells and its release into the peripheral blood stream and/or urine, and reduction of the normal immune function, which results in low immunoglobulin levels and increased vulnerability to infection.
Risk factors
Although the causes are unknown, myeloma has been associated with exposure to radiation, chemical products, herbicides, or insecticides and to genetic or infectious factors. It is most frequent in people over the age of 50 and among black races.
Prevention
There are no guidelines for the prevention of multiple myeloma, as its causes are unknown.
Symptoms
There are many symptoms that may appear years before diagnosis and which can easily be confused with other tumours.
The symptoms in the initial stages of myeloma include: persistent bone pain, often severe, together with fatigue. Approximately 70% of patients with myeloma suffer pain of varying intensity, which often affects the lumbar region of the spine or the hips. Severe pain that appears suddenly can be a sign of fracture or the crushing of a spinal component.
As the disease progresses, symptoms may include: fatigue, bone fractures, infections, nausea and vomiting, constipation, difficulty in urinating, abnormal bleeding, headaches, etc.
Diagnosis
Diagnosis is based on:
Biopsy of the bone marrow showing an abnormal presence (over 10%) of plasma cells in the bone marrow.
X-ray: lesions, erosions or fractures are found in 80% of patients.
Chromosome abnormalities related to the response or prognosis.
Study of tumour markers, such as beta 2-Microglobulin. Low levels of albumin, hypoalbuminaemia, together with high beta 2-Microglobulin point to a more negative prognosis.
Other blood and urine analyses are also useful to evaluate conditions associated with myeloma: anaemia, low levels of other cells in the blood, high levels of calcium (blood and urine) and signs of kidney damage and bone destruction.
Treatment
There is no consensus on the best way to treat myeloma. The first and most important decision is to determine whether or not any treatment is required. Patients suffering from asymptomatic myeloma should be closely monitored, but without applying any treatment. There are currently no therapies that stimulate the regulation of the immune system when myeloma is in the early stages or that prevent activation of the disease. However, possible treatments are currently being researched, such as anti-idiotype vaccinations. Treatment with bisphosphonates can be used once there is bone infection, even when it is in the very early stages. Erythropoietine is considered a treatment for cases in which there is only anaemia.
Treatment is not usually curative, except in the case of one solitary bone tumour or extramedullary plasmacytoma. In these cases external radiotherapy may be potentially curative. In other cases, there are a number of options, each of which should be evaluated. The general goal of treatment is to deal with the specific problems in order to achieve overall control of the disease.
The treatment options are:
Chemotherapy: there are a number of treatments, the most well known and traditional of which is a combination of melphalan and prednisone. Between 50%-60%% of patients respond to this treatment. There are other combinations with the addition of more aggressive drugs such as adriamycin or cyclophosphamide.
New drugs: thalidomide or its derivatives, lenalidomide or bortezomib.
Other treatments such as high-dose chemotherapy with autologous transplantation require individual evaluation. High doses, when they are effective, can prolong life, but they rarely cure.
On many occasions treatment of the complications is the most important aspect with regard to the survival of patients and their quality of life. To this end, hypercalcaemia is treated with bisphosphonates and intravenous liquids, when necessary, and kidney failure is corrected, even employing renal dialysis.