Leukemia represents itself a group of malignant diseases of blood cells. At leukemia, a whole group of tumors is characterized by the uncontrolled proliferation and varying degrees of differentiation of hematopoietic cells. As a rule, the cause of leukemia is the chromosomal aberration, i.e. changes in the structure of chromosomes as a result of various processes of their restructuring: translocations, deletions, inversions, and fragmentation. However, the symptoms of leukemia may depend on its type: chronic or acute, lymphocytic or myeloid. In this research, we aim at covering the causes and risk factors, course and symptoms of leukemia, changes it makes in the work of organ systems, as well as possible methods of its treatment.
Organ systems and their functions
On a whole, the hematopoietic system is the system of organs responsible for the constancy of blood composition. As the formed elements are continuously decomposing in the body (e.g., thrombocytes disintegrate in about a week), the main function of hematopoietic organs is a constant replenishment of the cellular elements of blood, i.e. blood formation. The main components of the hematopoietic system are the bone marrow, lymph nodes and spleen (Mughal et al., 2009).
Normally, the bone marrow of a healthy person is forming: erythrocytes (their main function is to transport oxygen and other substances to the body tissues), various forms of leukocytes (protecting the body from foreign agents and participating in the fight against infectious diseases) and thrombocytes (involved in blood clotting process) (Mughal et al., 2009).
In their turn, lymph nodes are involved in the process of hematopoiesis through producing lymphocytes and plasma cells. The spleen consists of red and white pulp. Red pulp is filled with hemocytes (mainly, with red blood cells), and white pulp is formed from the lymphoid tissue producing lymphocytes. In addition to hematopoietic function, the spleen performs the capture of damaged red blood cells from the flow of blood, as well as microorganisms and other foreign elements which get into the blood, and produces antibodies (Mughal et al., 2009; So, 2009).
Emergence and development of leukemia
Leukemia primarily occurs in bone marrow. The cause of leukemia is the mutations in one of the bone marrow cells: instead of developing into the normal mature white blood cell, it becomes a cancer cell. Abnormal white blood cell loses its ability to perform its functions and divides uncontrollably. As a result, the number of cancer cells increases and they begin to displace the healthy blood cells. This process results naturally in patients with leukemia developing different versions of cytopenia – anemia, thrombocytopenia, lymphocytopenia, granulocytopenia, which leads to increased angiostaxis, extravasation, immune suppression with the accession of infectious complications. Getting into the lymph nodes and other organs, leukemic cells cause lesions in them (Dingli et al., 2010; Mughal et al., 2009).
Symptoms of leukemia
Symptoms of leukemia vary greatly and depend on the form of the disease. In general, bone marrow damage caused by the replacement of normal bone marrow cells with a large number of immature and deformed white blood cells leads to the lack of platelets needed for blood clotting process, as well as to the lack of healthy white blood cells. As a result, patients with leukemia have bruising, bleeding, and petechiae. They also might develop tumors in various organs and susceptibility to infection. Lack of red blood cells causes anemia, which can lead to shortness of breath (Dingli et al., 2010; Mughal et al., 2009).
Metastasis in leukemia is accompanied by the appearance of leukemic infiltrates in various organs – the liver, spleen, lymph nodes; they usually increase, and may cause pain. Changes may develop in organs caused by obturation of the vessels with the tumor cells – infarctions, ulcer-necrotic complications (So, 2009).
The signs of leukemia also include headache, fever, pain in bones and joints, fatigue, frequent infections, poor appetite and weight loss (Dingli et al., 2010; Mughal et al., 2009).
Treatment of leukemia
Chemotherapy makes the basis of leukemia treatment. The treatment is protocolary today, that is why each type of pathology and its individual features are important for the choice of treatment protocol. In acute leukemia the treatment is based on chemotherapy. Its efficiency is higher in acute lymphatic leukemia, and reaches 95%. In acute myeloid leukemia the efficacy of chemotherapy is more than 80%, but is often accompanied by complications, and 5-year remission is observed in only 40% of patients, while relapse in acute lymphoblastic leukemia is a rarer phenomenon (Faderl & Kantarjian, 2010).
In the treatment of chronic myelogenous leukemia the effectiveness of chemotherapy does not reach 20-40%. The best results so far are shown by allogeneic bone marrow transplantation. Alpha interferon therapy also provides satisfactory results. Recently, great hopes have been placed on drugs that block tyrosine kinase activity of the protein Bcr-Abl, for example, the drug STI-571. It is believed that such drugs can be used to support monotherapy, i.e. for the prevention of blast crisis. Occasionally, the use of radiation therapy in the treatment of leukemia can be justified (Faderl & Kantarjian, 2010; So, 2009).
Prevention methods and risk factors
Most often, leukemia occurs in children and elderly people; however scientists do not know exactly what the causes of leukemia are. Still, some factors that may increase the risk of leukemia are determined (Mughal et al., 2009):
- Effects of large doses of radiation,
- Effects of certain cancer-causing chemicals (e.g., benzene, formaldehyde),
- Application of chemotherapy for cancer treatment of other types,
- Presence of Down syndrome or other genetic disorders,
- Family history of leukemia,
At the same time, it should be noted that many people who have been influenced by these risk factors are not suffering from leukemia, as well as the majority of patients with leukemia have never faced these risk factors in their lives. Therefore, scientists also do not know how to prevent leukemia. Still, it is recommended to avoid such risk factors as smoking, the effect of toxic substances and radiation. In some cases, it may help to prevent this serious disease (Mughal et al., 2009).
Thus, leukemia is a clonal cancerous neoplastic disease, caused by the mutations of bone marrow cells and interrupting the normal functioning of the hematopoietic system and normal course of the hematopoiesis process.
The common symptoms of leukemia include: unmotivated fever and night sweats, headaches, sarcothlasis or easy emergence of bleeding, pain in bones or joints, swelling or pain in the abdomen from an enlarged spleen or liver, enlarged lymph nodes, frequent infections, fatigue and weakness, weight loss.
In general, the treatment of leukemia should be conducted in a specialized department, with the possibility of applying the most modern and effective treatment of chemotherapy, radiotherapy, stem cell transplantion, which can ensure a greater probability of complete remission and full recovery after a full range of therapeutic measures.
Dingli, D., Traulsen, A., & Pacheco, J.M. (2010). Evolutionary Dynamics of Chronic Myeloid Leukemia. Genes & Cancer, 1(4), pp. 309-315.
Faderl, S., & Kantarjian, H. (2010). Leukemias: Principles and Practice of Therapy. Wiley-Blackwell.
Mughal, T.I, Goldman, J.M., & Mughal, S.T. (2009). Understanding Leukemias, Lymphomas and Myelomas. 2nd edn. Informa Healthcare.
So, C.W.E. (2009). Leukemia: Methods and Protocols. Humana Press.