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types of cancer

Leukemia

Overview

Leukemia (also spelled leukaemia), is a type of cancer of the blood that usually begins in the bone marrow. Leukemia occurs when there is an abnormal increase in under-developed blood cells called ‘blasts‘ or ‘leukemia cells’. This abnormality causes the blood cells to grow and divide chaotically. Normal blood cells die after a while and are replaced by new cells which are produced in the bone marrow. The abnormal blood cells do not die so easily. Instead they start accumulating and begin occupying the space intended for normal blood cells, which increases the chances of infection in the body. The different types of Leukemia are: CML: A Chronic Myeloid Leukemia (also known as granulocytic leukemia) is a cancer characterized with the abnormal growth of myeloid cells (cells from the bone marrow tissue). In CML, a genetic change in the immature version of the myeloid cells gives rise to the CML cell which can grow uncontrollably from the bone marrow to other parts of the body. Hairy cell Leukemia: This rare and slow growing cancer occurs when the bone marrow makes excessive number of B-cells (lymphocytes), which are a type of white blood cells responsible for fighting infections. The name ‘hairy cell’ is derived from the hairy appearance of the B-cell observed under a microscope. Acute Myeloblastic Leukaemia (AML): It is a type of cancer that affects the blood and bone marrow. AML is not a single disease, rather, it is a name given to a group of leukaemias that develop in the myeloid cell line in the bone marrow. Myeloid cells are red blood cells, platelets and all white blood cells excluding lymphocytes. AML results in an overproduction of immature white blood cells, called myeloblasts or leukaemic blasts. These cells crowd the bone marrow, and prevents it from making normal blood cells. They can also spill out into the bloodstream and circulate around the body. Due to their immaturity they are unable to function properly to prevent or fight infection. Inadequate numbers of red cells and platelets being made by the marrow can cause anaemia, easy bleeding, and/or bruising. Acute Lymphocytic Leukemia (ALL): It is a type of cancer that affects the blood and bone marrow and is characterised by an overproduction of immature white blood cells, called lymphoblasts or leukaemic blasts. Because the bone marrow is unable to make adequate numbers of red blood cells, normal white blood cells and platelets, people with ALL become susceptible to anaemia and recurrent infections. They also bruise and bleed easily and their healing process is slow. The blast cells can also spill out of the bone marrow into the bloodstream and accumulate in various organs including the lymph nodes (glands), spleen, liver and central nervous system (brain and spinal cord) T-Cell Acute Lymphoblastic Leukaemia (T-ALL): This specific type of Leukaemia is a variant of ALL (Acute Lymphocytic Leukemia). This cancer affects the white blood cell called T-lymphocytes as opposed to Lymphocytic Leukemia which affects the B lymphocytes. The T-Lymphocytes play an important function of helping the B-lymphocytes make the antibodies to fight infection. Leukemia is a treatable disease. Most treatments involve chemotherapy, medical radiation therapy, hormone treatments, or bone marrow transplant. The rate of cure depends on the type of Leukemia as well as the age of the patient. It can affect people at any age. About 90% of all Leukemia is diagnosed in adults. It is also the most common cancer type amongst children.

Symptoms

Like all blood cells, Leukemia cells travel through the body. The symptoms of Leukemia depend on the number of Leukemia cells and where these cells collect in the body. Patients suffering from acute leukemia may encounter symptoms such as headaches, vomiting, sickness, and loss of muscle control or seizure. Other common symptoms of leukemia include:

  • Poor Blood clotting: As immature white blood cells crowd out blood platelets (crucial for blood clotting), the patient may bruise or bleed easily and heal slowly. This symptom indicates that the patient is in the early stages of leukemia.
  • Affected immune system: The patient’s white blood cells, which are crucial for fighting off infection, may be suppressed or having difficulty in carrying out their function. The patient may experience frequent infections and in some cases his/her immune system may turn against the very healthy cells that they protect.
  • Anaemia: As the shortage of good red blood cells grows, the patient may suffer from Anaemia resulting in difficult or laboured respiration (dyspnea) and pallor (paleness in the skin caused by illness).
  • Other symptoms:
  • Nausea
  • Fever
  • Night sweats and tiredness
  • Sudden loss of weight
  • Headaches
  • Frequent infections
  • Fatigue
  • Easy bleeding and bruising
  • Swelling or discomfort in the abdomen (arising from a swollen spleen or liver)
  • Pain in the bones or joints
  • Stages of Leukemia
  • Stage 0: In the initial stages, there are too many lymphocytes in the body. The symptoms are rarely visible. Stage I: The lymph nodes start getting swollen due to too many lymphocytes being made. Stage II: The swelling spreads to the spleen and liver, again due to excessive presence of lymphocytes. Stage III: In this stage, the patient may experience anaemia since the lymphocytes are crowding out the red cells in the blood. Stage IV: In the final stage, very few platelets remain in the blood and the lymph nodes, spleen and liver continue to remain swollen.

    Causes

    There are various causes to the different types of leukemia. Some of the common causes associated with leukemia are:

  • Artificial Ionising Radiation – which can damage living tissue and cause cancer
  • Viruses – HTLV-1 (human T-lymphotropic virus) which are known to cause t-cell leukemia
  • Benzene and Petrochemicals – which contain carcinogenic chemical (cancer causing agents)
  • Diagnosis

    If a patient suffers from symptoms that are associated with Leukemia, one of the following tests will be recommended: Physical exam: The doctor will check if the skin is pale (due to anemia) and signs of swollen lymph nodes. Blood tests: The lab does a complete blood count to check the number of white blood cells, red blood cells and platelets. Leukemia causes a very high count of white blood cells. It may also cause low levels of platelets and haemoglobin, which is found inside red blood cells. Biopsy: The doctor removes tissue to look for cancer cells. A biopsy is the only sure way to know whether Leukemia cells are in the bone marrow. Before the sample is taken, local anaesthesia is used to numb the area. This helps reduce the pain. The doctor removes some bone marrow from the hipbone or another large bone. A pathologist uses a microscope to check the tissue for Leukemia cells. It involves two steps:

  • Bone marrow aspiration: It procedure that involves taking a sample of the liquid part of the soft tissue inside the bones
  • Bone marrow biopsy: The doctor uses a very thick, hollow needle to remove a piece of the bone marrow tissue.
  • Other tests may include:
  • Cytogenetics: The lab looks at the chromosomes of cells from samples of blood, bone marrow or lymph nodes. If abnormal chromosomes are found, the test can show the type of leukemia the patient is suffering from. For example, people with CML have an abnormal chromosome called the Philadelphia chromosome.
  • Spinal tap: The doctor may remove some of the cerebrospinal fluid (the fluid that fills the spaces in and around the brain and spinal cord). The doctor uses a long, thin needle to remove fluid from the lower spine. The procedure takes about 30 minutes and is performed with local anaesthesia. One must lie flat for several hours afterwards to avoid getting a headache. The lab checks the fluid for Leukemia cells or other signs of problems.
  • Chest x-ray: An X-ray can show swollen lymph nodes or other signs of disease in the chest.
  • Treatment

    Treatments for Leukemia include: Chemotherapy Chemotherapy is the treatment of disease with chemo-drugs, designed to kill cancerous cells. This is the main treatment for most types of Leukemia. Chemotherapy is often the primary treatment for children. In case the child suffers from high risk leukemia, then stem cell transplant is prescribed as well. The various side effects of chemotherapy include fatigue, hair loss, infection, nausea & vomiting. Radiation treatments Radiation therapy uses high-dose X-rays to destroy cancer cells and shrink swollen lymph nodes or an enlarged spleen. It may also be used before a stem cell transplant. Stem cell transplant Stem cells can rebuild the supply of normal blood cells and boost the immune system. Before the transplant, radiation or chemotherapy may be given to destroy cells in the bone marrow and make room for new stem cells. The procedure then involves infusing fresh stem cell back into the blood.

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