LEUKEMIA
Leukemia
Leukemia (British English: leukaemia) (Greek leukos λευκός, “white”; aima αίμα, “blood”) is a cancer of the blood or bone marrow and is characterized by an abnormal proliferation (production by multiplication) of blood cells, usually white blood cells (leukocytes). Leukemia is a broad term covering a spectrum of diseases. In turn, it is part of the even broader group of diseases called hematological neoplasms.
Symptoms
Damage to the bone marrow, by way of displacing the normal bone marrow cells with higher numbers of immature white blood cells, results in a lack of blood platelets, which are important in the blood clotting process. This means people with leukemia may easily become bruised, bleed excessively, or develop pinprick bleeds (petechiae).
White blood cells, which are involved in fighting pathogens, may be suppressed or dysfunctional. This could cause the patient’s immune system to be unable to fight off a simple infection or to start attacking other body cells. Because leukemia prevents the immune system from working normally, some patients experience frequent infection, ranging from infected tonsils, sores in the mouth, or diarrhea to life-threatening pneumonia or opportunistic infections.
Finally, the red blood cell deficiency leads to anemia, which may cause dyspnea and pallor.
Some patients experience other symptoms. These symptoms might include feeling sick, such as having fevers, chills, night sweats and other flu-like symptoms, or feeling fatigued. Some patients experience nausea or a feeling of fullness due to an enlarged liver and spleen; this can result in unintentional weight loss. If the leukemic cells invade the central nervous system, then neurological symptoms (notably headaches) can occur.
All symptoms associated with leukemia can be attributed to other diseases. Consequently, leukemia is always diagnosed through medical tests.
The word leukemia, which means ‘white blood’, is derived from the disease’s namesake high white blood cell counts that most leukemia patients have before treatment. The high number of white blood cells are apparent when a blood sample is viewed under a microscope. Frequently, these extra white blood cells are immature or dysfunctional. The excessive number of cells can also interfere with the level of other cells, causing a harmful imbalance in the blood count.
Some leukemia patients do not have high white blood cell counts visible during a regular blood count. This less-common condition is called aleukemia. The bone marrow still contains cancerous white blood cells which disrupt the normal production of blood cells. However, the leukemic cells are staying in the marrow instead of entering the bloodstream, where they would be visible in a blood test. For an aleukemic patient, the white blood cell counts in the bloodstream can be normal or low. Aleukemia can occur in any of the four major types of leukemia, and is particularly common in hairy cell leukemia.
Causes and risk factors
There is no single known cause for all of the different types of leukemia. The different leukemias likely have different causes. Known causes include natural and artificial ionizing radiation, viruses such as Human T-lymphotropic virus, and some chemicals, notably benzene and alkylating chemotherapy agents for previous malignancies.Use of tobacco is associated with a small increase in the risk of developing acute myeloid leukemia in adults. A few cases of maternal-fetal transmission have been reported.
Leukemia, like other cancers, results from somatic mutations in the DNA which activate oncogenes or deactivate tumor suppressor genes, and disrupt the regulation of cell death, differentiation or division. These mutations may occur spontaneously or as a result of exposure to radiation or carcinogenic substances and are likely to be influenced by genetic factors. Cohort and case-control studies have linked exposure to petrochemicals, such as benzene, and hair dyes to the development of some forms of leukemia.
Viruses have also been linked to some forms of leukemia. For example, certain cases of ALL are associated with viral infections by either the human immunodeficiency virus or human T-lymphotropic virus (HTLV-1 and -2, causing adult T-cell leukemia/lymphoma). However, one report suggests exposure to certain germs may offer children limited protection against leukemia.
Some people have a genetic predisposition towards developing leukemia. This predisposition is demonstrated by family histories and twin studies.The affected people may have a single gene or multiple genes in common. In some cases, families tend to develop the same kind of leukemia as other members; in other families, affected people may develop different forms of leukemia or related blood cancers.
In addition to these genetic issues, people with chromosomal abnormalities or certain other genetic conditions have a greater risk of leukemia.For example, people with Down syndrome have a significantly increased risk of developing forms of acute leukemia, and Fanconi anemia is a risk factor for developing acute myeloid leukemia.
Whether non-ionizing radiation causes leukemia has been studied for several decades. The International Agency for Research on Cancer expert working group undertook a detailed review of all data on static and extremely low frequency electromagnetic energy, which occurs naturally and in association with the generation, transmission, and use of electrical power. They concluded that there is limited evidence that high levels of ELF magnetic (but not electric) fields might cause childhood leukemia. Exposure to significant ELF magnetic fields might result in twofold excess risk for leukemia for children exposed to these high levels of magnetic fields. However, the report also says that methodological weaknesses and biases in these studies have likely caused the risk to be overstated. No evidence for a relationship to leukemia or an other form of malignancy in adults has been demonstrated. Since exposure to such levels of ELFs is relatively uncommon, the World Health Organization concludes that ELF exposure, if later proven to be causative, would account for just 100 to 2400 cases worldwide each year, representing 0.2 to 4.95% of the total incidence for that year.
Until the cause or causes of leukemia are found, there is no way to prevent the disease. Even when the causes become known, they may not be readily controllable, such as naturally occurring background radiation, and therefore not especially helpful for prevention purposes.
WHAT IS LEUKAEMIA?
The body is made up of many types of cells. In normal course, cells grow, divide, and produce more cells to keep the body healthy. However, at times, this process may not function properly and cells may become abnormal, forming more cells, in an uncontrolled manner. Leukaemia is a cancer of ‘blood cells.’ It is commonly known as blood cancer. In this cancer the bone marrow starts producing abnormal blood cells, which grow at a very fast rate and outnumber the other blood cells like normal white blood cells, red blood cells (cells that carry oxygen to all parts of the body) and platelets (cells that help form blood clots that control bleeding). These abnormal blood cells are knows as leukaemia cells.
TYPES OF LEUKAEMIA
There are various types of leukaemias, which can be broadly divided into 2 types :
Acute Leukaemia : Here the symptoms become evident early and therapy will begin immediately after diagnosis.
Chronic Leukaemia : Here the symptoms are not evident early and the patient may not require immediate treatment. Treatment will start once the symptoms become evident and he will be kept under maintenance therapy.
WHAT ARE THE SYMPTOMS OF LEUKAEMIA ?
Since blood cells travel throughout the body, this means the leukaemia cells are also travelling through the body. Therefore, symptoms can erupt anywhere, depending on the body part where the leukaemia cells have accumulated.
Some of the common symptoms to look out for are :
- * Prolonged fever
* Night sweats
* Frequent infections
* Feeling weak or tired
* Headache
* Bleeding and getting bruised easily(bleeding gums, purplish patches in the skin, or tiny red spots under the skin)
* Bone or joint pain
* Swelling or discomfort in the abdomen(from an enlarged spleen)
* Swollen lymph nodes, especially in the neck or armpit
* Weight loss
HOW IS LEUKAEMIA DIAGNOSED ?
If the symptoms suggest leukaemia, your doctor will ask for a detailed medical history and will do a physical examination before conducting any of the following tests : Blood count : This is done to ascertain the increase in the number of white blood cells, which is the most evident sign. Blood chemistry : This test will reveal whether the liver and kidneys have been affected. Bone Marrow Examination : It is the most certain way of diagnosing leukaemia. After administering local anaesthesia, your doctor will use a needle to extract a sample of the bone marrow, which will be examined under a microscope to spot leukaemia cells.