Leukemia is cancer of the bone marrow found in the flat bones. It is the most common in children, and can be acute or chronic or chronic. Its diagnosis is very important in order to administer treatment as soon as possible. Research continues in search of a cure.
Leukemia: what it is and types
Leukemia comes from the Greek word leukos (white) and haima (blood). It is defined as a cancer of the bone marrow found inside the flat bones. In this cancer, malignant cells called blasts increase in what are known as acute leukemias or cells in a certain state of maturation but aberrant, in what are called chronic leukemias, which can originate from any of the precursors of blood cellularity (red blood cells, white blood cells and their cytological varieties: granulocytes, monocytes, lymphocytes and platelets). Consequently, it causes a decrease in production and maturation of the rest of the hematological series. Cancer cells can spread from the bone marrow to the bloodstream, lymph nodes, spinal cord and central nervous system, as well as other parts of the body.
Prevalence of Leukemia
We can say that leukemia is the most frequent type of cancer in childhood, with an incidence of 3 to 5 cases per 100,000 children/year, especially in its acute variety. In adults the incidence is variable and ranges between 1-3 cases/100,000 inhabitants and year with a prevalence that depends on the type between 1.5-7% of the total number of tumors.
On the other hand, although there is no single known cause for the different types of leukemia that exist, those factors that are known and that are not intrinsic to each patient represent relatively few cases; thus, each distinct leukemia may have a variety of different causes.
Causes and Origins of Leukemia
Leukemia, like most tumors, is the result of a mutation of one or more genes that produce activation of substances called oncogenes or deactivation of those genes that produce tumor suppression, thereby altering the cell’s cycle of regulation of death or apoptosis, differentiation or multiplication. These mutations can occur either spontaneously or as a result of exposure to radiation or carcinogenic chemicals, in addition to the probable influence of certain genetic predisposition.
Among the most common factors that have been associated with the production of certain types of leukemia are:
- Infection by a certain type of virus
- Ionizing radiation
- Chemical substances such as alkylating agents
- Benzene
- Certain types of chemotherapy drugs
- Tobacco
- Certain petrochemicals
- Hair dyes, among others
Cases have also been described of transmission between mother and fetus, in addition to certain chromosomal abnormalities, such as Down syndrome or Fanconi’s anemia.
A controversial fact is exposure to non-ionizing energy. According to expert commissions, they have concluded that exposure to low-frequency non-electrical electromagnetic fields could double the incidence of childhood leukemia. Although there are a priori contradictory data, the conclusion is that the real annual incidence ranges from 0.20 to 5%.
Symptoms of Leukemia
In the case of chronic leukemias, the clinical manifestations are more insidious and can often go unnoticed with a slow evolution, while in acute leukemic processes the symptoms are more florid, with a rapid course.
In summary, as any cell line of the hematological extirpation can be affected, the symptomatology is very varied. Some characteristic symptoms may be:
- Decay, lack of strength, dizziness, nausea, vomiting, poor appetite, significant weight loss.
- Fever without apparent cause, which may last several weeks.
- Pain and increased bone, joint and/or limb tenderness
- Frequent bleeding for no apparent reason
- Pallor of skin and mucous membranes
- Enlargement of the lymph nodes
Diagnosis of Leukemia
As in any hematological process, the diagnostic approach must be systematized and structured, starting with a good anamnesis, inquiring about family or personal history, followed by a structured physical examination in search of indirect signs that may lead us to suspect the etiological process: peripheral lymphadenopathy, visceromegaly, bleeding spots, pallor, cachexia, etc.
According to the aforementioned, the hematology specialist will perform the relevant analytical and morphological laboratory studies that may include genetic or immunohistochemical tests or cytology to label the leukemic picture.
It will be necessary, if the preliminary results suggest it, to resort to the study of the blood or bone marrow factory to see if there are signs of disease in it.
Finally, imaging tests may be useful to assess the extent of the disease.
Treatment and prognosis of leukemia
The treatment and prognosis will depend mainly on the type of leukemia being treated and may range from simple observation to the application of systematized protocols of chemotherapy and radiotherapy, or even transplantation of hematopoietic progenitors in the case of acute leukemias.
The prognosis will depend, fundamentally, of:
- The type of etiological entity
- The response to initial treatments
- The presence or not of certain types of oncogenes or chromosomal mutations.
- age
- The presence or not of comorbidities
Can leukemia be cured?
Today we are still far from finding a cure for this disease, and the cure rate is low, below 15%. For most of these clinical entities, the only curative option with a morbidity and mortality rate of up to 35-45% of cases is allogeneic transplantation of hematopoietic progenitors. Although this therapy has evolved a lot since its inception back in the 1960s, less aggressive procedures called microtransplants are currently available, with an acceptable response rate, although increasing the possibility of relapse.
A couple of years ago, the first therapy was successfully tested in the USA in a patient with acute leukemia by means of gene therapy through a vector (attenuated measles virus), which succeeded in curing the disease. However, studies are still needed for the development and evaluation of the benefit of this type of treatment.