Leukemia is a malignant disease (cancer) of the bone marrow and blood. It is characterized by the uncontrolled accumulation of blood cells. Leukemia is divided into four categories: myelogenous or lymphocytic, each of which can be acute or chronic. The terms myelogenous or lymphocytic denote the cell type involved. The are four major types of leukemia.

Leukemia is cancer of blood-forming tissue such as bone marrow. Types of leukemia are grouped by the type of cell affected and by the rate of cell growth. Leukemia is either acute or chronic.

Leukemia is a type of cancer. Cancer is a group of many related diseases. All cancers begin in cells, which make up blood and other tissues. Normally, cells grow and divide to form new cells as the body needs them. When cells grow old, they die, and new cells take their place.

Over time, the leukemic cells spread through the bloodstream where they continue to divide, sometimes forming tumors and damaging organs such as the kidney and liver. Since the spleen is responsible for filtering the blood and destroying old cells, it may become enlarged and swollen with the abnormal cells, as can the liver and lymph nodes.

Causes

As with other cancers, smoking is considered a risk factor for leukemia, but many people who develop leukemia have never smoked, and many people who smoke never develop leukemia. 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.

Symptoms

Two general categories of leukemia are acute and chronic. In acute leukemia, symptoms appear quickly and worsen quickly. This form of leukemia may develop over a short period of days to weeks. Abnormal white blood cells may collect in the brain or spinal cord. The result may be headaches, vomiting, confusion, loss of muscle control and difficulty seeing. Some patients develop sores in the eyes or unusual skin rashes. Leukemia also can affect the lungs and other parts of the body.

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 become bruised, bleed excessively, or develop pinprick bleeds (petechiae).

Treatment

Your doctors will consider the scientific evidence that the treatment works for your type of leukemia, and any other health issues you have. You will be encouraged to help make the final treatment choices. Cancer patients often have a combination of treatments.

Chemotherapy. Chemotherapy is the major form of treatment for leukemia. This treatment uses chemical agents to kill leukemia cells. Depending on the type of leukemia you have, you may receive a single drug or a combination of one or more drugs. These drugs may come in a pill form, or they may be injected directly into a vein.

Biological therapy. Also known as immunotherapy, biological therapy uses substances that bolster your immune system's response to cancer.