Leukemia, or cancer of the blood, is characterized by the production of abnormal white blood cells in bone marrow, the soft interior region of most bones. There are several types of it, categorized according to the type of white blood cells most affected by cancer and the aggressiveness of the disease. Leukemia cells are able to multiply quickly and outlive normal blood cells.
Bone marrow is the home of blood stem cells that give rise to platelets (responsible for helping blood to clot), red blood cells (responsible for transporting oxygen to regions of the body), and white blood cells (responsible for fighting infection in body). Leukemia cells overwhelm and interfere with healthy blood cells, compromising blood cell function and transporting quickly through the bloodstream.
Most Common Types of Leukemia:
- Acute myelogenous leukemia (AML):
- overproduction of immature myeloid (granulocytes and monocytes) white blood cells
- Chronic myelogenous (CML): abnormal accumulation of myeloid white blood cells.
- Acute lymphocytic (ALL): overproduction of immature lymphocytes.
- Chronic lymphocytic (CLL): abnormal accumulation of lymphocytes.
Acute leukemia progresses much more quickly than the chronic disease. In acute it, genetic mutations in the blood-forming cells result in an excess of immature, useless blood cells in the bone marrow and blood, essentially crowding out the production of healthy marrow cells. As a result, the marrow cannot produce enough red blood cells, many types of white blood cells and blood-clotting platelets, leaving individuals anemic and susceptible to infection and bleeding. In chronic leukemia, more mature, working cells are made. While chronic leukemia cells are more functional than acute leukemia cells, over time, they will also overcrowd and interfere with the function of healthy cells.
In 2008, researchers estimate that approximately 44,270 cases of it will be diagnosed among adults and children in the United States.
- Leukemia is the most common form of cancer in children.
- CLL is the most commonly diagnosed leukemia in adults.
- ALL is the most common leukemia in children.
Researchers estimate that 3,040 of 4,220 new cases of ALL this year will be in children; 87 percent of children with ALL will survive at least five years after being diagnosed with cancer
Thanks to medical and technological advances, the survival rates of it patients have dramatically improved over the last several decades. Overall, children tend to respond better to it treatments; however, chemotherapy and radiation can have long-term effects on patients' health.
Symptoms usually develop fairly quickly in acute leukemias. Most cases of acute are diagnosed when the person visits his or her healthcare provider after becoming ill. Symptoms develop gradually in chronic leukemias and are generally not as severe as in acute leukemias. About 20% of people with chronic it do not have symptoms at the time their disease is diagnosed.
Some symptoms of leukemia are due to deficiencies of normal blood cells. Others are due to collections of it cells in tissues and organs. It cells can collect in many different parts of the body, such as the testicles, brain, lymph nodes, liver, spleen, digestive tract, kidneys, lungs, eyes, and skin — in effect, virtually every tissue site.
The following symptoms of leukemia are common to all types:
- Unexplained fevers.
- Frequent infections.
- Night sweats.
- Fatigue (feeling tired or washed out).
- Weight loss.
- Easy bleeding or bruising.
Collection of leukemia cells in certain parts of the body may cause the following symptoms:
- Balance problems.
- Blurred vision.
- Painful swellings in the neck, under the arms, or in the groin.
- Shortness of breath.
- Nausea or vomiting.
- Abdominal pain and/or swelling.
- Testicular pain and/or swelling.
- Pain in the bones or joints.
- Weakness or loss of muscle control.
It is important to emphasize that the symptoms of leukemia are nonspecific. This means that they are not unique to leukemia but are common to a number of diseases and conditions. Only a medical professional is able to distinguish leukemia from the other conditions that cause similar symptoms.
Causes and Risk factors:
The exact cause of leukemia is unknown.
As with other cancers, smoking is considered a risk factor for this, but many people who develop leukemia have never smoked, and many people who smoke never develop it.
Long-term exposure to chemicals such as benzene or formaldehyde, typically in the workplace, is considered a risk factor for leukemia, but this accounts for relatively few cases of the disease.
Prolonged exposure to radiation is a risk factor, although this accounts for relatively few cases of this. Doses of radiation used for diagnostic imaging such as x-rays and CT scans are nowhere near as prolonged or high as the doses needed to cause leukemia.
Other risk factors for leukemia include the following:
Previous chemotherapy: Chemotherapy, particularly certain of the alkylating agents and topoisomerase inhibitors, used to treat certain types of cancers, are linked to the development of leukemia later. It is likely that radiation treatment adds to the risk of leukemia associated with certain chemotherapy drugs.
Human T-cell leukemia virus 1 (HTLV-1): Infection with this virus is linked to human T-cell leukemia.
Myelodysplastic syndromes: In this unusual group of blood disorders, the net outcome is invariably an acute myelocytic process.
Down syndrome and other genetic diseases: Some diseases caused by abnormal chromosomes may increase the risk for leukemia.
Family history: Having a first-degree relative (parent, brother, sister, or child) who has chronic lymphocytic it increases one's risk of having the disease by as much as 4 times that of someone who does not have an affected relative.
To identify leukemia, a patient will need to undergo blood and bone marrow cell tests that provide information about total blood counts and any genetic abnormalities reflected in blood and bone marrow. These genetic abnormalities can include chromosomal translocation (the exchange of DNA between different chromosomes) or the possession of extra chromosomes. Imaging tests are used to identify the damage caused by leukemia and to identify if cancer has spread to other regions of the body (metastasized).
Based upon the number, type, and characteristics of abnormal cells found in blood and bone marrow tests, leukemia will be diagnosed. The type of leukemia will influence the treatment a patient will receive.
Exams and Tests: Because the symptoms of leukemia are nonspecific and the causes are not clearly defined, one's health care provider will carry out extensive interviews and any appropriate tests in order to identify the underlying cause.
The health care provider will ask many questions about symptoms, current medical situations, medications, medical and surgical history, family history, work history, and habits and lifestyle.
The physical examination includes a thorough evaluation of all symptoms, not merely lymph nodes and/or possible enlargements of the liver and spleen.
Blood tests: Blood is drawn from a vein in order to check the blood cell counts. In most cases of leukemia, the white blood cell count is very high (although it is not uncommon for the white cell count to be normal in many of the childhood acute lymphocytic leukemias) and the platelet and red cell counts are low. This makes the healthcare provider consider leukemia as the diagnosis. Other tests are performed to check liver and kidney functions and the possible presence of leukemic cells in the spinal fluid.
Biopsy: Because other conditions may give rise to atypical white cell counts, the only way to confirm the diagnosis of leukemia is via an aspirate and biopsy of the bone marrow.
A biopsy means to take a small sample of the relevant tissue to check for abnormal cells. In leukemia, a biopsy of the bone marrow must be taken and examined.
This procedure is usually performed in the medical office, usually by a specialist trained in the treatment of blood disorders, that is, a hematologist or a hematologist-oncologist. The procedure is brief (less than a few minutes) and preceded by a local injection for relief of pain.
Samples of both liquid (aspirate) and solid bone marrow (biopsy) are taken, usually from a hip bone. The bone marrow is examined under a microscope, where the presence of leukemic cells confirms the suspected diagnosis.
Genetic studies: The chromosomes of the abnormal cells are examined to look for irregularities. This helps in classifying the various types of leukemia.
Lumbar puncture (spinal tap): Because the collection of leukemia cells in the central nervous system can affect mental processes, it is extremely important to know whether the fluid surrounding the brain and spinal cord (cerebrospinal fluid) are affected.
This procedure is referred to as a lumbar puncture or spinal tap and is usually carried out by the blood specialist in the office. After the procedure, the person needs to lie flat for 1-2 hours.
A small amount of the fluid is removed from the area around the spinal cord by inserting a hollow needle in the back at around the waist level. The needle is inserted in between the bones in the spine following a small injection into the skin over the injection site in order to minimize discomfort. The fluid is examined for the presence of leukemia cells.
Lymph node excision: If the lymph nodes are enlarged, a node may require a biopsy if the bone marrow is difficult to interpret for some obscure reason. This is exceedingly uncommon.
Chest x-ray: A chest x-ray film is frequently taken to look for signs of infection or lymph node involvement by leukemia.
Staging: Staging is the way cancers are classified. Staging indicates the size or extent of cancer, the degree to which other parts of the body are affected, and other important details. In general, leukemias are classified rather than staged in order to determine the most appropriate therapy.
All leukemias are classified according to their genotypes, or their unique chromosomal arrangements, which also enables the physicians to determine risk factors.
In addition, chronic myelogenous leukemia is classified by phase. The 3 phases are chronic phase, accelerated phase, and blast phase (or "blast crisis") and are defined by the number of blasts (leukemia cells) in the blood and bone marrow.
Chronic lymphocytic leukemia is classified by 2 different staging systems, both based on the parts of the body affected by leukemia.
Surgery: Because leukemia rapidly spreads throughout the body and does not form tumors, surgery has a limited role in treating it. However, the spleen may be removed if it is enlarged.
Chemotherapy: Chemotherapy, the use of drugs to destroy cancer cells, is the major treatment of it. Anti-cancer drugs can be taken by vein, muscle, cerebrospinal fluid (CSF) or mouth.
Although chemotherapy techniques wipe out cancer cells, many normal, rapidly dividing healthy cells are also killed by these treatments. The death of healthy cells causes undesirable side effects for cancer patients such as hair loss, mouth sores, nausea, reduce resistance to infection, bruising and more. To lessen the harmful side effects caused by chemotherapy, researchers are working to develop ways to tailor anti-cancer drugs that specifically target cancer cells and interfere with the chemical processes that promote cancer growth.
The goal of chemotherapy is to destroy leukemia cells and help to return blood counts to normal. There are a variety of anticancer drugs used either alone or in combination to treat it.
Radiation: Radiation therapy fights cancer by damaging cancer cells with a powerful blast of energy. While researchers direct radiation at cancer cells, they cannot be fully isolated and radiation often kills normal, healthy cells of the body.
Radiation therapy is most commonly used to target high percentages of leukemia cells gathered in specific regions of the body, such as the brain or cerebrospinal fluid. Some leukemia patients receive whole-body radiation to help destroy leukemia cells, but this is only in preparation for bone marrow or blood stem cell transplant.
Bone Marrow or Blood Stem Cell Transplant: Many leukemia patients suffer from the side effects of losing healthy cells in addition to leukemia cells from chemotherapy and radiation. To help a patient to withstand high doses of chemotherapy and radiation, healthy stem cells and bone marrow can be transplanted to a leukemia patient. A stem cell and/or bone marrow treatment will help the patient to generate new, healthy blood cells.
Bone marrow and stem cell transplants are still very new and expensive.
As researchers continue to better understand the molecular events leading to it, they continue to work towards specific drugs that will halt the disease's progression. The development of new drugs and combinations of drugs that target particular proteins found in leukemia cells continues to be a major area of research and discovery.
Researchers also continue to work to improve other leukemia treatments. In June 2007, scientists reported a drug already proven safe in humans may be able to help increase the number of blood-producing stem cells, which may help to improve the effectiveness of stem cell transplants.
Because more children are surviving childhood it than ever before, new research focuses on the long-term effects of cancer therapy on adult survivors of childhood leukemia. Studies have shown that adult survivors of childhood ALL are at a higher risk for obesity, developing cardiovascular disease, osteoporosis and more. In order to protect adult survivors of childhood leukemia from the disease in the future, special medical attention needs to be focused on how children are treated and followed. Promoting healthy lifestyles in adult survivors could help minimize complications
Other Therapy: While alternative therapies, such as supplements, herbs, and body therapies, are not recommended as a replacement for medical treatment in it, they may be considered complementary therapies.
The following therapies have proponents but no scientific evidence of unequivocal benefit:
- Coenzyme Q10.
- Polysaccharide K.
Alternative or complementary therapies should be discussed with the treating specialist. These therapies are not offered in conjunction with chemotherapy for leukemia because of the lack of definitive data.
Medicine and medications:
Common chemotherapy drugs for the treatment of each type of leukemia are used:
- Vincristine (Oncovin®).
- Cyclophosphamide (Cytoxan).
- L-asparaginase (Elspar®).
- Daunorubicin (Cerubidine®).
- Methotrexate (Trexall).
- Daunorubicin (Cerubidine®).
- Cytarabine (Cytosaur ®).
- Idarubicin (Zavedos®).
- Etoposide (Etopophos®, Vepesid®).
- Mitoxantrone (Novantrone).
- Hydroxyurea (Hydrea®).
- Busulfan (Myleran®).
- Fludarabine (Fludara®).
- Chlorambucil (Leukeran®).
- Cyclophosphamide (Cytoxan).
Additional drugs used in combination with chemotherapy:
- Imatinib mesylate (Gleevec®).
Monoclonal antibodies: proteins specifically designed to attach to and promote the death of leukemia cells
In addition to chemotherapy drugs, patients may also take medications to reduce side effects of chemotherapy, antibiotics to protect against infection, and blood transfusions to help replenish low blood counts.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.
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