Leukaemia Pages - What is it?

Cancer is not just one disease but rather a group of diseases. All forms of cancer cause cells in the body to change and grow out of control. Most types of cancer cells form a lump or mass called a tumor. Cells from the tumor can break away and travel to other parts of the body. There they can continue to grow. This spreading process is called metastasis. When cancer spreads, it is still named after the part of the body where it started. For example, if breast cancer spreads to the lungs, it is still breast cancer, not lung cancer.

Another word for cancerous is malignant. So a cancerous tumor is called malignant. But not all tumors are cancer. A tumor that is not cancer is called benign. Benign tumors do not grow and spread the way cancer does. They are usually not a threat to life. A few cancers, such as blood cancers (leukaemia), do not form a tumor.

Leukaemia is cancer of the white blood cells. This cancer starts in the bone marrow but can then spread to the blood, lymph nodes, the spleen, liver, central nervous system and other organs. In contrast, other types of cancer can start in these organs and then spread to the bone marrow (or elsewhere). Those cancers are not leukaemia. Both children and adults can develop leukaemia.

Leukaemia is a complex disease with many different types and sub-types. The kind of treatment given and the outlook for the person with leukaemia vary greatly according to the exact type and other, individual factors.

In order to understand the different types of leukaemia, it is helpful to have some basic knowledge of the blood and lymph systems. Following is an explanation of some of the parts of these systems.

Bone marrow is the soft, spongy, inner part of bones. All of the different types of blood cells are made in the bone marrow. In babies, bone marrow is found in almost all the bones of the body. But by the teen-age years, it is found mostly in the flat bones such as those of the skull, shoulder blades, ribs, pelvis, and back bones.

Bone marrow is made up of blood-forming cells, fat cells, and tissues that aid the growth of blood cells. Early (primitive) blood cells are called stemcells. These stem cells grow (mature) in an orderly process to produce red blood cells, white blood cells, and platelets.

Red blood cells carry oxygen from the lungs to all other tissues of the body. They also carry away carbon dioxide, a waste product of cell activity. A shortage of red blood cells (anemia) causes weakness, shortness of breath, and tiredness.

White blood cells (leukocytes) help defend the body against germs, viruses and bacteria. There are quite a few types (and subtypes) of white blood cells. Each has a special role to play in protecting the body against infection. The three main types of white blood cells are granulocytes, monocytes, and lymphocytes. The suffix - cyte means cell.

Platelets are actually pieces that break off from certain bone marrow cells. They are called platelets because they look a little bit like plates when seen under the microscope. Platelets help prevent bleeding by plugging up areas of blood vessels damaged by cuts or bruises.

The lymphatic system consists of lymph vessels, lymph nodes, and lymph fluid.

Lymph vessels are like veins except that they carry a clear fluid, lymph, instead of blood. Lymph is composed of excess fluid from tissues, waste products, and immune system cells.

Lymph nodes (sometimes called lymph glands) are pea-sized organs found along the lymph vessels. Lymph nodes collect immune system cells. The nodes get bigger when they fight infection. Swollen lymph nodes are not usually serious, especially in children but rarely they can be a sign of leukaemia when the cancer has spread outside the bone marrow.

There are four major types of leukaemia:

acute vs. chronic & lymphocytic vs. myelogenous

Acute means rapidly growing. Although the cells grow rapidly, they are not able to mature properly.

Chronic refers to a condition where the cells look mature but they are not completely normal. The cells live too long and cause a build-up of certain kinds of white blood cells.

Lymphocytic and myelogenous (or myeloid) refer to the two different cell types from which leukaemias start. Lymphocytic leukaemias develop from lymphocytes in the bone marrow. Myelogenous leukaemia develops from either of two types of white blood cells: granulocytes or monocytes.

By looking at whether a leukaemia is acute or chronic and myelogenous or lymphocytic, most cases of leukaemia can be sorted into one of the four main types shown in the table below. And, while both children and adults can develop leukaemia, certain types are more common in one age group than in another.

In addition to these four main types, there are a few other, less common, subtypes of leukaemia. The purpose of this article is to provide an overview of the two main types of adult chronic leukaemia. More detailed information about each type of leukaemia is available from the American Cancer Society.

(The table below shows the four major types of leukaemia and their distribution among children and adults.)

The American Cancer Society predicts that, in the year 2000, there will be about 30,800 new cases of all types of leukaemia in this country. Of these, about 12, 500 will be chronic leukaemia: 8,100 chronic lymphocytic leukaemia (CLL) and 4,400 chronic myelogenous leukaemia (CML). The remaining cases are of other chronic types.

Chronic leukaemia affects mostly older adults. Only about 2% of chronic leukaemia patients are children.

A risk factor is something that increases a person's chance of getting a disease. Some risk factors, like smoking, can be controlled. Others, such as a person's age, can't be changed. Smoking is a proven risk factor for leukaemia. Although many people know that smoking causes lung cancer, few realize that it can affect cells that do not come into direct contact with smoke. Cancer-causing substances in tobacco smoke get into the bloodstream and spread to many parts of the body, increasing the risk of cancer.

There are some factors in the environment that are linked to chronic leukaemia. For example, high-dose radiation exposure (such as from an atomic blast or nuclear reactor accident) increases the risk of CML but not CLL. Long-term contact with herbicides or pesticides among farmers can increase their risk of CLL.

There is some concern about very high-voltage power lines as a risk factor for leukaemia. The NCI has several large studies going on now to look into this question. So far, the studies show either no increased risk or a very slightly increased risk. Clearly, most cases of leukaemia are not related to power lines.

The only known inherited risk factor for chronic leukaemia is having first-degree relatives (parents, siblings, or children) who have had CLL.

Most people who develop leukaemia, however, do not have any of the above risk factors. The cause of their leukaemia remains unknown at this time. Because the cause is not known, there is no way to prevent most cases of leukaemia. The exception is smoking, which has been shown to increase the risk of leukaemia. People who smoke should attempt to quit.

At this time, there are no special tests that can find chronic leukaemia early. The best course of action is to report any symptoms to the doctor right away. These symptoms are discussed in the section that follows.

Symptoms of Chronic Leukaemia

About one out of five people with chronic leukaemia have no symptoms at the time their cancer is found. In these cases, the cancer is found by blood tests done for some other reason. Even when there are symptoms, they may be very general. Keep in mind that the symptoms mentioned below are most often caused by something other than cancer.

General symptoms of chronic leukaemia can include fatigue, weakness, weight loss, fever, and bone pain. Most symptoms of chronic leukaemia are caused by a shortage of normal blood cells, a result of the crowding out of normal blood cell-producing bone marrow by leukaemia cells. As a result, the person doesn't have enough properly working red blood cells, white blood cells, and platelets.

Anemia is a result of a shortage of red blood cells. Anemia causes shortness of breath, fatigue, and a pale skin color.

Not having enough normal white blood cells can increase the risk of infection. Although people with leukaemia may have very high white blood cells counts, the cells are not normal and do not protect against infection very well.

Not having enough blood platelets can lead to bruising, bleeding, frequent or severe nosebleeds, and bleeding from the gums.

Spread of leukaemia outside of the bone marrow to other organs or the central nervous system can cause a variety of symptoms such as headaches, weakness, seizures, vomiting, trouble in keeping one's balance, and blurred vision.

Some people have bone pain or joint pain caused by the spread of cancer cells to the surface of the bone or into the joint.

Leukaemia can also cause swelling of the liver and spleen. If the disease has spread to the lymph nodes, these nodes may be swollen.

Just because a person has some of the symptoms listed above does not mean that they have leukaemia. The doctor will want to conduct certain tests to find out if the disease is present and, if so, what type of leukaemia it is.

Changes in the numbers of different blood cell types and how the cells look under a microscope can suggest leukaemia. Most people with chronic leukaemia, for example, will have too many white blood cells, not enough red cells, and not enough platelets.

People with leukaemia will have tests done to measure the amount of certain chemicals in the blood. These tests do not tell if they have leukaemia but can help tell how well their kidneys are working. The test results also help the doctor decide whether treatment is needed to correct low or high blood levels of certain minerals.

In bone marrow aspiration, a thin needle is used to draw up a small amount of liquid bone marrow. During a bone marrow biopsy, a small cylinder of bone and marrow (about ½" long) is removed with a slightly larger needle.

Both samples are usually taken at the same time from the back of the hipbone. These tests are used to tell whether leukaemia is present and also, if the person is having treatment, how well the disease is responding.

In this procedure, an entire lymph node is removed. If the node is near the skin's surface, a simple operation can be done by numbing just the area around the node. But if the node is inside the chest or abdomen, the patient will need general anesthesia. This procedure is only rarely needed for people with leukaemia.

In this procedure, a small needle is placed into the spinal cavity in the lower back to draw out some cerebrospinal fluid. The fluid is examined for leukaemia cells. This test is only done for patients with chronic leukaemia if it looks as if there may be leukaemia cells in their brain or spinal cord.

Doctors use a number of very precise laboratory tests to diagnose and classify leukaemia. You might hear some of the following terms used: cytochemistry, flow cytometry, immunocytochemistry, cytogenetics, and molecular genetic studies. These tests are explained in the American Cancer Society's document, Leukaemia: Adult Chronic.

Doctors with special training in blood and lymphoid tissue disease examine all of the biopsy samples (bone marrow, lymph node tissue, blood, and cerebrospinal fluid) under a microscope. They look at the size and shape of the cells as well as other features to classify the cells into specific types. An important goal of this process is to see whether the cells appear mature or not. The most immature cells are called blasts. These blasts are not effective in fighting infections, but they can reproduce, crowding out normal, mature cells.

Imaging studies are ways of producing pictures of the inside of the body. There are several kinds of these studies that might be done in people with leukaemia.

X-rays are often taken to see if there is a mass in the chest, or evidence of leukaemia in the bones or, rarely, in the joints.

CT (computed tomography) scans are special kinds of x-rays in which a beam moves around the body, taking pictures from different angles. CT scans are not often used in leukaemia, but they can show if there is disease in the lymph nodes of the chest or in back of the abdomen.

MRI (magnetic resonance imaging) is a method that uses powerful magnets and radio waves to produce detailed, computer-generated pictures of the body. This scan might be used when there is concern about leukaemia invading the brain.

Ultrasound uses sound waves to produce images of internal organs. This test can distinguish solid from fluid-filled masses. Ultrasound is also used to show whether the kidneys, liver, or spleen have been affected by leukaemia.

Most types of cancer are assigned a stage (I, II, III, or IV) based on the size of the tumor and how far it has spread. This system generally does not apply to leukaemia because leukaemia is a disease of the blood cells and does not usually form a solid mass or tumor.

Leukaemia involves all the bone marrow and, in many cases, has already spread to other organs in the body. For leukaemia, lab tests focus on providing a clear description of different features of the disease. These features, in turn, help predict the likely outcome for the patient and help to guide treatment decisions.

Different staging systems are used for different types of chronic leukaemia. Some types do not have any staging system. Some patients might find this information about staging helpful; others may find it a bit overwhelming. If you would like to read about the staging of chronic leukaemia, please consult the American Cancer Society's document, Leukaemia: Adult Chronic.

As noted before, adult chronic leukaemia is not a single disease. It is really a group of diseases, and people with different types vary in how they respond to treatment. Treatment options are based on the type as well as on certain features of the disease called prognostic features.

Chemotherapy refers to the use of anticancer drugs that enter the bloodstream and spread throughout the body to kill cancer cells. Chemotherapy is the main treatment for chronic leukaemia.

Chemotherapy of leukaemia often involves a combination of several drugs given over a period of time. While chemotherapy drugs kill cancer cells, they can also damage normal cells. This happens because they target rapidly growing cells such as cancer cells, but in the process they also damage other fast growing cells.

Bone marrow, the lining of the mouth and intestines, and hair follicles all grow rapidly and are likely to be affected by chemotherapy. As a result, people being treated with chemotherapy may have a higher risk of infection (from low white blood cell counts), may bruise or bleed easily (from low blood platelets), and tire easily (from low red blood cell counts). Other side effects of chemotherapy can include temporary hair loss, nausea, vomiting, and loss of appetite.

These side effects usually go away shortly after treatment ends. There are often ways to manage these side effects during treatment. For example, there are drugs than can be taken along with the chemotherapy to prevent or reduce nausea and vomiting. Drugs known as growth factors are sometimes given to keep blood counts higher and reduce the chance of infection.

Other ways people can reduce the risk of infection are by avoiding exposure to germs as much as possible by carefully washing hands and not eating uncooked fruits and vegetables. Patients in treatment should also avoid large crowds and people who are sick.

During treatment, patients might also receive powerful antibiotics as added protection. They might start taking these at the first sign of infection, or even earlier as a preventive measure. If platelet counts are low, they might receive platelet transfusions, and red blood cell transfusions if low red cell counts are causing shortness of breath or fatigue.

Tumor lysis syndrome is a side effect caused by the rapid breakdown of leukaemia cells. When these cells die, they release substances into the bloodstream that can affect the kidneys, heart, and nervous system. Giving the patient extra fluids or certain drugs that help rid the body of these toxins can prevent this problem. Tumor lysis is more common among patients with acute leukaemia than those with chronic leukaemia.

Interferons are natural substances that the body produces. They can help the body's immune system slow the growth of leukaemia cells. Interferon is usually given as a shot once a day.

Side effects can include muscle aches, bone pain, headaches, problems with thinking, tiredness, nausea, and vomiting. These problems usually go away when treatment ends, and there are drugs to help reduce the side effects during treatment.

Radiation therapy, the use of high energy x-rays to kill cancer cells, has a limited role to play in the treatment of people with leukaemia. For some people with an enlarged spleen or other organs, radiation might be used to shrink the swelling. It is also useful in treating bone pain caused by growth of leukaemia cells within the bone marrow.

Unlike with most other cancers, surgery is not generally used to treat leukaemia. This is because leukaemia is a disease of blood and bone marrow and it is not possible to bring about a cure with surgery.

Surgery, however, may be used to help deliver treatment. A plastic tube can be surgically placed into a large vein. The tube, called a venous access device, allows chemotherapy drugs or other medicines to be given and blood samples removed without the need for repeated needle sticks.

The only operation commonly used for treating leukaemia is removal of the spleen. If leukaemia spreads to the spleen it can cause the organ to become large enough to press on other organs and cause problems. If this happens, removing the spleen can provide relief, although it does not cure the leukaemia.

As noted earlier, chemotherapy can harm normal cells as well as cancer cells. Stem cell transplantation offers a way for doctors to use the high doses of chemotherapy needed for effective treatment. Although the drugs destroy the patient's bone marrow, transplanted stem cells can restore the blood-producing bone marrow stem cells.

It works like this: stem cells for transplantation are collected from the bone marrow or from the bloodstream (in a process called apheresis). These stem cells can come from either the patient or from a suitable donor. For people with chronic leukaemia, a donor's cells are most often used because it's hard to find cancer-free cells in the patient's own marrow.

Patients are then given very high doses of chemotherapy to kill the cancer cells. They also receive total body radiation to kill any remaining cancer cells. After therapy, the stored stem cells are given to the patient as a blood transfusion. Then the waiting period begins as the stem cells settle in the patient's bone marrow and start to grow and produce blood cells.

People who receive a donor's stem cells are given drugs to prevent rejection as well as other medicines as needed to prevent infections. Usually around 10 to 21 days after the stem cells are infused, they begin making white blood cells. Then they begin making platelets, and finally, red blood cells.

Patients having SCT have to be kept away from germs (in protective isolation) as much as possible until their white blood cell count is at a safe level. They are kept in the hospital until the white cell count reaches a certain number, usually around 1,000. After they go home, they will be examined in the outpatient clinic almost every day for several weeks.

Stem cell transplantation is still a fairly new and complex treatment. If the doctors think that a person with leukaemia might be helped by this treatment, it is important that it be done at a hospital where the staff have experience with the procedure. Some transplant programs may not have experience in certain transplants, especially those from unrelated donors.

Stem cell transplantation is very expensive and requires a lengthy hospital stay. Because some insurance companies see it as an experimental treatment, they might not pay for it.

Side effects from stem cell transplantation can be divided into early and long-term effects. Early side effects are basically the same as those of any other type of high-dose chemotherapy. They are caused by damage to the bone marrow and other rapidly reproducing tissues of the body.

Side effects can go on for a long time. Sometimes they don't show up until years after the transplant. The long-term side effects could include the following:

Radiation damage to the lungs, causing shortness of breath
Graft-versus-host disease, which happens only in donor transplants. This serious side effect happens when the donor's immune system cells attack tissues of the patient's skin, liver, mouth, or other organs. Symptoms include weakness, fatigue, dry mouth, rashes, infection, and muscle aches.
Damage to the ovaries causing infertility and loss of menstrual periods
Damage to the thyroid gland that causes problems with metabolism
Cataracts (damage to the lens of the eye)
Bone damage; if damage is severe, the patient will need to have part of the bone and joint replaced.

Frequent follow-up exams are needed for several years after the treatment for chronic leukaemia. These follow-up visits are very important. The doctors will continue to watch for signs that the leukaemia has come back, as well as for side effects. It is important that cancer survivors report any new symptoms to the doctor right away, so that they can be treated.

If the leukaemia does come back, it usually happens during treatment or shortly after treatment ends. It is unusual for the leukaemia to return if there are still no signs of the disease five years after treatment.