Myeloproliferative Neoplasms – Leukemia & Lymphoma

Blood is very important for the life of the body. All cells circulating in the blood originate from the bone marrow, in which various cell lines originate from hematopoietic stem cells: hematopoietic cells are constantly dividing and maturing. Hematopoietic cells can also develop tumors (tumors of the hematopoietic tissue): – leukemia and lymphoma. How can one detect these tumors in order to achieve the best results of treatment? The purpose of this article is to introduce the most important problems associated with blood diseases.

What is leukemia?

Leukemia is a malignant tumor of white blood cells, it can be called blood cancer. It is characterized by an uncontrolled increase in the number of cells of a certain type since disturbances in the DNA carrying hereditary information of cells cause disturbances in the normal mechanisms of control of the stem cell. Basically, there are 4 forms of leukemia, which have many subtypes: 1. Acute myeloid leukemia (AML) 2. Chronic myeloid leukemia (CML) 3. Acute lymphoblastic leukemia (ALL) 4. Chronic lymphocytic leukemia (CLL)

Leukemia accounts for about 3% of all malignant tumors. Of all other forms of cancer, ALL is the most common in children. In adolescence, AML and CML are diagnosed more often than ALL and CLL. CLL is very rare in people under the age of 40. The incidence of AML and ALL increases significantly in people over 60 years of age, and the risk of developing CLL also increases with age.

Is leukemia a hereditary disease?

Most leukemia patients do not have a family member with the same disease. Although isolated cases are described when 2 or more family members fall ill with leukemia. The genetic or molecular basis of leukemia is not currently known, although a certain genetic predisposition can be suggested. Some people with genetic disorders (eg, Down’s syndrome, Bloom’s syndrome) are more likely to develop leukemia.

Is leukemia contagious?

NO. The only exception is the rare HTLV-1 virus, which can cause a leukemia-like disease that attacks T-lymphocytes. This disease is diagnosed in certain regions of the Caribbean and Japan. The disease is transmitted sexually and with body fluids. Can animal leukemia be transmitted to humans? There are many viruses that cause cancer in animals, including leukemia. These viruses have never been found in people with leukemia. There is no evidence of transmission of leukemia from animals to humans.

What are the risk factors for leukemia?

Leukemia occurs when damage is located in the cell nucleus carrying hereditary information DNA (deoxyribonucleic acid – carries the information necessary for cell growth, division and work), which can affect genes. Thus, DNA damaging factors can induce the development of leukemia. This includes a number of chemical compounds (benzene and other solvents), ionizing radiation, as well as drugs used in the treatment of other tumors (chemotherapeutic drugs). For example, in this way, SECONDARY LEUKEMIA often occurs after chemotherapy for breast cancer, Hodgkin’s lymphoma, and multiple myeloma. Smokers are twice as likely to develop leukemia than non-smokers. Can power lines cause leukemia? Many studies have been conducted, but no evidence has been found that living near power lines can contribute to the development of leukemia. In fact, in the case of most patients with leukemia, no clear cause of the disease can be found.

What are the signs of leukemia?

Leukemia can manifest itself in different ways. Some patients have no symptoms at all, and the disease is discovered by chance during a blood test. For example, an abnormally large or even small number of leukocytes is found. The number of platelets may be reduced, changes characteristic of anemia (decrease in the number of red blood cells) may be observed. Many people have symptoms for which they go to the doctor, but they can be very mild and non-specific. For example, FATIGUE is a very common symptom of anemia. INFECTIONS that do not respond to antibiotics and last for a long time can also indicate leukemia. BLEEDING from the gums and nose can be caused by a low platelet count. In addition, small red dots and blue spots can be found on the body, especially on the legs and arms. Some patients experience a feeling of heaviness in the abdomen after eating: this may be caused by an enlarged spleen (especially characteristic of CML). In children, ALL can be expressed in swollen lymph nodes, pain in the joints. With leukemia, there may be a slight increase in temperature, pain in the bones and joints, night sweats. If you have worsening fatigue, bleeding, frequent infections, be sure to consult a doctor. Keep in mind that most people who experience fatigue and carry infections do not have leukemia. But we must not forget that leukemia is a serious disease, early suspicion of this disease and its diagnosis is very important.

What is lymphoma?

Lymphoma is a tumor of the lymphatic system. The tumor cell originates from a lymphocyte, which began to multiply uncontrollably. Typically, tumor cells cover the lymph nodes, which are enlarged. Abnormal cells can also be found in the bone marrow, blood, spleen, as well as in other organs (in the intestines, lungs, brain, skin). There are two main types of lymphomas: Hodgkin’s lymphoma and non-Hodgkin’s lymphoma. Since 1970, the incidence of lymphomas has doubled. Hodgkin’s lymphoma Got its name from the English pathologist Thomas Hodgkin, who first described this disease in 1832. This is a tumor of the lymphatic system, which most often occurs at age 20 or after 50.

Non-Hodgkin’s lymphoma

The name refers to the many different lymphatic tumors, in which the tumor cells have a different appearance and thus mean a different prognosis of the disease. Non-Hodgkin’s lymphomas are the fifth most common among all tumors. From 1975 to 2004, the incidence rate increased to 84%, the average increase in the incidence rate annually is 2.8%.

What is the role of the immune system in lymphomas?

The cells of the immune system are designed to recognize foreign proteins, but they also play an important role in protecting the body from abnormal cells. Lymphomas occur when cells of the immune system (lymphocytes) change into abnormal ones. Compared to normal cells, such a diseased cell has a greater ability to survive. To recognize a diseased cell, cells of the immune system must identify cell surface proteins as foreign. In the case of lymphomas and many other tumors, the surface proteins of cells are similar to “self”, so the body’s immune response to tumors is weak. In some cases, lymphomas occur when lymphocytes overreact to certain types of infections. It is believed that one of the mechanisms for the development of tumors is that the immune system does not recognize abnormal cells even before a tumor arises from it.

What are the signs of lymphoma?

The main symptom of lymphoma is enlarged lymph nodes – this symptom is called LYMPHADENOPATHY. Lymph nodes may be enlarged in the neck, armpits, or groin. Enlarged lymph nodes are usually painless, but if enlarged quickly, they can become painful. Along with superficial lymph nodes, the tumor may also involve the stomach or digestive tract, causing abdominal pain and/or a feeling of heaviness. If the lymph nodes are enlarged in the chest, you may experience coughing, difficulty breathing, or chest pain. If the tumor involves the bone marrow, anemia and resulting weakness or fatigue may develop. As a result of a decrease in the number of platelets, bleeding gums, bleeding from the nose, and a rash on the skin in the form of red dots may occur. Decreased white blood cell count contributes to susceptibility to infections. Rarely, lymphoma can also involve the brain, causing severe headache, double vision, and weakness in the arms and legs. If the canal of the spinal cord is affected, back pain, weakness of the legs, numbness, disorders of the intestines and bladder may appear.

Usually, these symptoms indicate compression of the spinal cord by lymphoma. Other symptoms that may appear regardless of the location of the lymphoma are FEVER, NIGHT SEATS, WEIGHT LOSS. These are the so-called B-symptoms. Many patients have no symptoms at all. Enlarged lymph nodes may be found incidentally, such as in the shower or bed. An increase in lymph nodes can be detected by a doctor when examining a patient. None of these symptoms are a sign of lymphoma alone. Enlarged painful lymph nodes in most cases are caused by infections. If the lymph nodes are enlarged for a long time or are constantly enlarged (especially if they are painless), you should contact your family doctor.

What causes lymphoma?

In general, the causes of lymphoma are unknown. It’s easier to list what DOES NOT CAUSE LYMPHOMA. No association was found between smoking or alcohol consumption. The risk of developing lymphoma does not increase with different diets or lifestyles. Also, excess weight does not have a causal relationship with the development of lymphoma. Lymphoma is not transmitted from one person to another. Medical scientists tried to find the causes of lymphoma, but in most cases these connections turned out to be very weak. Prolonged contact with chemicals (insecticides and pesticides) contributes to the development of lymphoma.

The risk of developing lymphoma is increased by abnormalities in the functioning of the immune system. The most striking example is the acquired human immunodeficiency syndrome (AIDS), which is caused by the human immunodeficiency virus (HIV). The virus infects lymphocytes, thus disrupting the immune system. Some of these patients subsequently develop lymphoma. After kidney, liver, heart, and lung transplants, people receive drugs that slow down the immune system for a long time to prevent transplant rejection. This inhibition of the immune system contributes to the development of lymphoma. The development of lymphoma may be related to the EPSTEINBARR virus, which causes infectious mononucleosis (also called kissing disease, since this disease occurs in young people and the virus is known to be transmitted through saliva). It has been found that the virus can cause abnormal growth of B-lymphocytes. Occasionally, EpsteinBarr virus is found in leukemia patients in lymphoma cells, indicating the possibility that the virus plays an important role in causing lymphoma. There may be another explanation: immunodeficiency, which contributes to the development of lymphoma, also contributes to infection with the Epstein-Barr virus without the virus itself being able to play a role in the development of lymphoma. It has recently been found that the hepatitis C virus can also contribute to the development of lymphoma. This is worrying since the number of people infected with this virus has increased significantly in 20 years.

How is leukemia treated?

Leukemia is a systemic disease, so the treatment used must permeate throughout the body. There is no place for surgery here. Also, the possibilities of irradiation are limited. Leukemia is mostly treated with “chemotherapy”. This is the so-called treatment with cytotoxic drugs (cell poisons), which destroy leukemia cells. There are various medications available to treat different forms of leukemia. Drugs are taken either by mouth (eg, imatinib, hydroxyurea) or through blood vessels (eg, cytosine arabinoside, fludarabine, doxorubicin), and some forms of leukemia require injection of drugs into the spinal canal. An important achievement in recent years, of course, is the introduction of imatinib (Glivec) for the treatment of chronic myeloid leukemia. Of note is the treatment with tretinoin (ATRA), which is similar in structure to vitamin A. The drug is used to treat one acute myeloid leukemia, in which case ATRA can direct tumor cells to maturation. In the case of various forms of leukemia, various combinations of drugs are also used.

How is lymphoma treated?

Lymphomas are inherently different, so their treatment is different. First of all, it should be clarified whether the goal of treatment is to recover from the disease or control it. Even if some lymphoma cannot be completely cured, there are ways to keep the disease under control for many years. Recently, many new drugs and treatments have appeared. In the treatment of lymphomas, CHEMOTHERAPY, RADIATION and BIOLOGICAL TREATMENT are used.

Chemotherapy

The goal of chemotherapy is to kill lymphoma cells; various preparations are used for this. The newest and still the most effective treatment for this disease is the treatment with monoclonal antibodies. Mostly combinations of different drugs are used. For many years drugs such as chlorambucil and cyclophosphamide, doxorubicin have been used. New opportunities have opened up with the use of the drug fludarabine. Vincristine and vinblastine, etoposide, ifosfamide, carboplatin and others are also used in combinations.

Radiation

Radiation energy is used to destroy tumor cells during irradiation. Tumor cells grow faster than normal cells and are therefore more sensitive to radiation. Radiation is used in the treatment of lymphomas mainly in combination with chemotherapy.

What is immune therapy?

In the treatment of a disease, they use molecules acting through immune mechanisms, or the patient’s immune system itself. Monoclonal antibodies are proteins, which are also called immunoglobulins, they are produced by cells of one population or clone. Antibodies can fight tumor cells. For example, the CD20 protein (antigen) is found in most of the tumor cells of a patient with lymphoma. Rituximab (Mabthera) is one of the first widely used immunotherapy drugs in the world. When rituximab is injected into the bloodstream, it finds the CD20 molecule located on tumor lymphocytes and attacks it, thus killing the cell. Alemtuzumab (MabCampath) has a similar mechanism of action, which attacks the CD52 molecule located on the surface of lymphocytes. Ibritumomab tiuxetan (Zevalin) also attacks CD20, although it carries a radioactive molecule, itrium, to do so. In this case, the radiation mainly attacks the lymphoma cells, affecting normal cells less. In the case of Hodgkin’s lymphoma, disease-free survival 5 years after diagnosis is 86%, in children – 95.2%. In the case of non-Hodgkin’s lymphoma, disease-free survival 5 years after diagnosis is 63.8%, in – children 83.5%.

Conclusion

Each person is the master of his body. Take care of yourself: if you notice changes in how you feel or how you look, see your doctor.