Multiple myeloma, a tumor that accounts for 10% of all blood cancers

Multiple myeloma: what it is

Multiple myeloma is a type of blood tumor characterized by a clonal proliferation of a subtype of bone marrow cell, called a plasma cell. It is classified as a type of evolved monoclonal gammopathy. Monoclonal gammopathies are a heterogeneous group of diverse diseases that have in common an abnormal production of immunoglobulins and/or the appearance of plasma cell tumors (plasmacytomas or multiple myeloma).

How does multiple myeloma occur in the blood?

Plasma cells produce immunoglobulins or antibodies, proteins that circulate in the blood with the mission of defending the organism. Each immunoglobulin consists of two heavy chains: Gamma (IgG), Alpha (IgA), Mu (IgM), Delta (IgD) or Epsilon (IgE); and two light chains: Kappa (K) or Lambda (L).

Monoclonal gammopathies include a group of diseases characterized by the clonal proliferation of plasma cells that produce a single type of light and/or heavy chain, which is called a monoclonal component.

In the case of multiple myeloma, the plasma cells produce large amounts of monoclonal immunoglobulin that can be detected in both blood and urine. This excess of immunoglobulins produces alterations in the physiological functioning of the blood, favoring infections, as the rest of the immunoglobulins are not adequately produced in the kidneys and bones (in whose bone marrow the rest of the hematological series are formed), altering hematopoiesis and normal production of red blood cells, platelets and the rest of the white blood cells.

Incidence of multiple myeloma in the population

Multiple myeloma is the most common plasma cell neoplasm. It tends to affect predominantly older people, from 55 years of age onwards. In Spain its incidence is 40 new cases per million inhabitants per year, a figure that represents 1% of all tumors and approximately 10% of hematological cancers.

Signs and symptoms produced by multiple myeloma

The main symptom of multiple myeloma is bone pain, which occurs in 75% of patients. Although it can occur anywhere, the most frequent areas are usually the spine, pelvis and ribs. Due to alteration of the rest of hematopoiesis, other symptoms that we can observe are related to the lack of production and/or functioning of the rest of the hematological series:
– Anemia (tiredness, weakness, dizziness, palpitations).
– Superficial hemorrhages (spontaneous hematomas, gingivorrhages, epistaxis).
– Tendency to infections

In addition, 80% of patients may present osteoporosis (when one or more areas of a bone are worn out or diminished) or spontaneous bone fractures at the time of diagnosis. The most frequently affected regions are the skull, spine, ribs, sternum, pelvis and long bones such as the femur. In addition, approximately 25% of affected patients present renal insufficiency at diagnosis.

How to diagnose multiple myeloma

The diagnosis of monoclonal gammopathy and/or multiple myeloma will be made by the hematologist when demonstrating in blood and/or urine the abnormally elevated presence of a monoclonal immunoglobulin, accompanied or not by an excess of plasma cells in bone marrow or, much more rarely, in peripheral blood (plasma cell leukemia). It is also important to carry out a thorough electrolyte study of the patient, especially serum calcium, as well as renal function, through the pertinent blood and urine tests.

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It is very important, when a suspected diagnosis is made, to perform what is called a bone series to evaluate, by means of radiographic images, those regions where the presence of fractures or other osteolytic lesions is more frequent, either because of prevalence or because of the patient’s symptomatology.

Finally, cytogenetic studies are necessary, which are of vital importance when it comes to establishing an adequate prognostic and treatment scheme.

Treatment and prognosis of multiple myeloma

Monoclonal gammopathy only requires observation for periods of time ranging from three to six months, with controls of hemogram, biochemistry with calcium and renal function and dosage of immunoglobulins in both blood and urine.

There is currently a consensus among the various specialists in hematology when starting treatment for multiple myeloma, so that it is only treated when any of the following signs or symptoms appear:
– Anemia
– Hypercalcemia
– Renal insufficiency
– Spontaneous osteolytic lesions/bone fractures

However, nowadays there are frequent clinical trials with novel cytostatic drugs in earlier stages of the disease, which will require careful indication by the specialist.

In general, for patients under 70 years of age, treatment will be based on cytostatic protocols containing Bortezomid or Lenalidomide, in preparation for autologous hematopoietic stem cell transplantation, which is the standard treatment in this age group of patients. The purpose of this treatment is to slow the progression of the disease and to control the symptoms, since, to date, there is no curative treatment for myeloma.

The only potentially curative treatment would be allogeneic transplantation of hematopoietic progenitors. Unfortunately, the advanced age of the patients when the disease is diagnosed, together with the high toxicity of the cytostatics used, reduce the possibility of applying this therapy. Currently, reduced-intensity allogeneic hematopoietic stem cell transplantation, also known as double autologous bone marrow transplantation or “tandem transplantation”, is being considered, which offers some hope of survival in this group of patients, decreasing toxicity but increasing the chances of disease relapse.

Likewise, radiotherapy is a very effective therapeutic option for localized forms of the disease or plasmacytomas.

Finally, the use of bisphosphonates, which inhibit the lytic action of osteoclasts, offers a complementary possibility by facilitating bone recalcification.

All of the above already shows that the prognosis of these patients will depend, fundamentally, on age, the degree of the disease at diagnosis, the general physical condition of the patient and the presence of certain types of genetic alterations which indicate an increased aggressiveness of the disease.

Without treatment the half-life of patients used to be approximately 6 months. However, thanks to the new therapeutic options available, the median survival has increased from 3 to 5 years, a survival increased by the option of autologous hematopoietic stem cell transplantation.

However, even so, relapse can occur even two years after transplantation. This can reach 50% of cases and successive treatments offer increasingly shorter periods of remission and control of the pathology.

The introduction of cytostatic molecules of the Bortezomid or Lenalidomide family has reported longer periods of remission of the disease, but they do not offer a definitive curative option to date.

The only existing curative option, as previously mentioned, would be allogeneic hematopoietic stem cell transplantation.