The leukemias are cancers of the blood forming cells. Acute leukemia involves the most primitive of these types of cells. This class of cancer leads to an overproduction of a blood cells that have similar characteristics (clones). Clonal cells share two common features that lead to the symptoms of leukemia.

1) The cells divide without control and fail to respond to the signals that tell them to stop.

2) These cells have a longer life than normal cells and gradually accumulate in the bone marrow.

This uncontrolled production of long lived cells leads to the replacement of the normal cells in the bone marrow with leukemic clones. Since the space is limited in the marrow, the normal cells are crowded out by these clones. All the normal blood forming elements are eventually affected if the leukemia goes unchecked. So that the white cells (infection fighters), platelets (clot forming cells) and red blood cells (oxygen carrying cells) are all eventually depleted. The lower number of normal white blood cells makes leukemic patients more vulnerable to infection. The depletion of normal platelets interferes with the patients clotting ability and makes the patient more susceptible to abnormal bleeding and bruising. Anemia is caused by the decreased production of normal red blood cells. Leukemic cells are actually abnormal white blood cells. As these cells proliferate they increase the concentration of white blood cells in the blood stream. The term leukemia actually has a latin derivation. Leuko means white and heme is blood. Therefore the word leukemia literally means white blood. Now you understand why INFECTIONS, ANEMIA AND EASY BRUSING ARE THE HALLMARKS OF LEUKEMIA. Other features include enlarged spleen, liver and lymph nodes. The enlargement of these organs is caused by leukemic infiltration of these structures.

TREATMENT

The treatment of leukemia continues to advance. Improved understanding of the basic disease process as well as better drugs and supportive care are leading to more cures and remissions. The outlook is much better now then it was even ten years ago. The biotechnology revolution offers hope of even better treatments in the near future. Treatment is divided into two categories 1) supportive and 2) chemotherapy treatment with chemical drugs.

Supportive Care refers to treatments which help the patient, but do not attempt to fight the leukemia. These include:

-blood transfusions-to relieve the anemia

-platelet transfusions-to help prevent bleeding

-antibiotics-to control infections

-Growth factors-these stimulate the production of normal cells in the marrow. Examples include drugs like Granulacyte colony stimulating factor (Neupogen ) that helps increase the production of normal white cells and erythroietin (Epogen) which stimulates red blood cell production.

-Institution of special precautions like isolation procedures-these decrease the risk of exposure to disease and are usually only implemented when the patient is considered to be at increased risk.

Chemotherapy

Chemotherapeutic agents are chemicals that have the ablity to kill cancer cells. They usually work on cells that are dividing. Actually, these chemicals kill all cells that are dividing. This includes both the normal and leukemic cells. The knowlege of how fast these various types of cells divide is used by oncologist in designing their plan of attack.

Oncologists give patients chemotherapeutic agents which they know will kill actively dividing cells. This effectively wipes out the cells which are dividing in the marrow. The killing of normal cells is maximum at 7-10 days after the start of therapy. This is the stage when the patient's ability to form blood cells is most limited. It is often referred to as the nadir (low point). At this point the oncologist gives the patient so called supportive care. Antibiotics and isolation technques are used to help prevent infection. Blood products or blood stimulating factors can also be administered. After the nadir the STEM CELLS are stimulated to divide. These dividing stem cells act to replenish the normal bone marrow. The fact that normal cells divide faster and more effectivley acts to the patients advantage. If the therapy is effective a bone marrow obtained 28 days after the treatment will reveal a normal appearance. Effectively the patient will be in REMISSION at that point.

The primary therapy for acute non-lymphocytic leukemia is chemotherapy. The two most commonly used chemotherapeutic agents are Idarubicin and cytosine arabinoside (ARA-C). Some physicians may use daunomycin and ARA-C. These agents are given intraveneously for 3 and 5-7 days in the hospital. The initial hospitalization usually requires 3-4 weeks . After chemotherapy the patients usually require supportive care. Supportive care may include antibiotics as well as blood and platelet transfusions. Patients under the age of 50 may be candidates for bone marrow transplantation, but patients older than 60 usually do not tolerate this mode of therapy well.

The initial remission rate for acute leukemia is on the order of 70-80% for people younger than 40 years of age. Approximately 20-30 % of patients live longer than 3 years. It must be remembered that all patients are individuals. Statistics only count in research studies. Many factors can influence the response rate in patients. Above all it is important to maintain an optimistic attitude.