Thursday, June 9, 2011

Blood Cancer - Leukemia

Introduction

Leukemia means "white blood" but it is not as commonly called, blood cancer. It is a cancer of the tissues in which blood is formed.

Bone marrow, the soft, spongy center of the bone, produces red blood cells, white blood cells and platelets.

Red blood cells carry oxygen to cells through- out the body and, if there are too few, symptoms such as anemia, shortness of breath appear: white blood cells fight infection, and platelets, which control blood clotting, prevent hemorrhaging.

The spleen and the lymph nodes produce a type of white blood cell called lymphocyte. Lymphocytes produce antibodies, act against infection, and contribute to the body's own immune system.

All blood-forming tissues daily release millions of each type of cell into one of the body's two circulatory systems-the blood vessel system and the lymph system. When leukemia strikes, millions of abnormal, immature white blood cells called leukocytes are released into these circulatory systems.

Because these cells are immature, they cannot carry out their basic function of fighting infection. In advanced leukemia, the uncontrolled multiplication of abnormal cells results in crowding out the production of normal white cells to fight infections, of platelets to control hemorrhaging and of red blood cells to prevent anemia.

There are several types of leukemia, depending on the white cell that is multiplying. About 90 percent of cases are caused by two types of leukocytes: lymphocytic leukemia (also called lymphoblastic), involving cells formed in lymphatic tissue and granulocytic leukemia (also called myelocytic), involving cells found in bone-marrow.

Both the lymphatic and granulocytic types have acute or swift growing, and chronic or slow growing, forms. The two types of cells and two rates of growth produce four main types of leukemia in human beings: acute lymphocytic, chronic lymphocytic, acute granulocytic and chronic granulocytic.

Risk Factors

The causes of most cases of human leukemia are unknown. Excessive exposure to radiation and to certain chemicals, such as benzene, have been linked to the development of leukemia. Certain viruses are known to cause leukemia in animals, but this has not been proven so in humans. There is some evidence of an inherited susceptibility but none that the disease is transmitted directly from parent to child, It is known that there is a higher than normal incidence of leukemia among children with Down's syndrome (mongolisR1), and certain other hereditary abnormalities may be linked to leukemia.

Age is a factor to the extent that the different types of leukemia generally strike different age groups.

Leukemia strikes more children than any other form of cancer and is the leading cause of death by disease among chlldren aged 3 to 15. The type of leukemia common among children is acute lymphocytic leukemia. Fortunately it is with this type of childhood leukemia that the greatest progress in treatment and survival is being made. Children do get acute granulocytic leukemia, but much less frequently.

The type of leukemia most prevalent in young adults is acute granulocytic.

Chronic leukemia, whether granulocytic or lymphocytic, generally appears after the age of 40. Adult may also be struck by acute leukemia, however-either granulocytic or lymphocytic.

More than half of all cases of leukemia occur in persons over 60 years of age.

Signs and Symptoms

There are no definite early signs of leukemia.

Acute Leukemia
Acute leukemia in children usually appears rather suddenly with symptoms similar to those of a cold and progresses rapidly. Lymph nodes, spleen and liver become enlarged with white blood cells that accumulate in these organs. Because leukemic cells circulate throughout the body via the blood and lymph systems, the patient may develop a variety of generalized complaints.

Early signs and symptoms may include fatigue, paleness, loss of appetite, weight loss, repeated infections, night sweats, bone and joint pain, fever, easy bruising, nose bleeds or other hemorrhages. There may also be enlargement of the liver, spleen and lymph nodes, and anemia.

Symptoms of advanced leukemia include extreme fatigue, massive hemorrhages, pain, high fever, swelling of the gums and various skin disorders.

Sometimes chronic leukemia in adults later develop into acute leukemia. In these cases, the symptoms of the acute from progress more slowly than in children.

Chronic Leukemia
Chronic leukemia comes on slowly and without warning signs. Many cases are discovered during routine blood tests, but significant signs - and symptoms may not appear for several years. When they do develop, signs and symptoms resemble those of the acute forms of the disease; fatigue, tendency to bruise and bleed easily, and increased susceptibility to infections. The physician can often feel an enlarged spleen or lymph nodes.

Diagnosis

Leukemia is diagnosed by microscopic examination of the blood and bone marrow cells. Blood samples are taken in the usual way by drawing a small amount of blood from a vein in the arm of finger. The bone marrow sample biopsy) is taken by the aspiration technique, in which a needle is inserted after skin anesthesia and the tissue sample withdrawn through suction. The breastbone or the bone at the top of the hip is usually selected for bone marrow biopsy. The patient will experience only a slight sensation of pressure as the needle is inserted; when the marrow is withdrawn, there will be a few seconds of pain which the patient will be forewarned of by the physician.

These cell samples are examined for excessive numbers of the abnormal white blood cells characteristic of specific types of leukemia.

The blood samples reveal the number of white blood cells, red blood cells and platelets in the blood and if leukemic cells have entered the circulatory systems.

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