Understanding Leukemia

It started out as a little headache and a low-grade fever; a 10-year old boy being sent home from school by the nurse on a regular basis. Isaiah, an Alaska Native, was an outgoing child whose favorite activities included Nintendo, fishing, and watching wrestling on TV. His mother became concerned when her little boy grew tired, lost his appetite and the energy to run outside and play. Sitting and watching TV became the only activity he could endure. It was time for a visit to the health clinic. The doctor ordered tests and told her he would get back to her with the results. No one in the family could have expected the results. Isaiah’s blood work indicated he had an aggressive form of cancer, acute myelogenous leukemia.*

Leukemia is a cancer of the blood; it is unique because of the impact it has on young children.

According to the American Cancer Society, Cancer Facts and Figures 1996, leukemia was the eighth leading cause of cancer death in the United States for Native Americans. In the United States, leukemia is the number one killing disease of children between 1 and 14 years old.

In order to understand leukemia it helps to have a basic understanding of the function of normal blood cells. The three major types of blood cells are red blood cells, white blood cells, and platelets. These cells are produced in the bone marrow; they then circulate through the blood stream in a liquid called plasma.

	Red Blood Cells Your blood gets its color from the red blood cells (Fig. 1). Red blood cells are the major component of blood. Their job is to carry oxygen and carbon dioxide throughout the body. Oxygen is transported from the lungs to the body’s tissues, and carbon dioxide is transported from the tissues back to the lungs. Red blood cells are very important to our body’s function because all body tissues need oxygen to function properly.
Fig. 1 Normal Red Blood Cells
White Blood Cells White blood cells are another type of blood cells. The duty of these cells is to help our body fight infections and other disease. White blood cells are classified into several different types, each with its own function in fighting off germs. Neutrophils, monocytes and lymphocytes are three major types:
	Neutrophils (Fig. 2) kill most regular bacteria and accumulate as pus with an infected wound on skin. Most white blood cells are of this type, created in response to acute body stress. For example, when you have infections, trauma, or emotional distress your body produces these white blood cells. Neutrophils are your soldiers who are called to battle the enemy at the site of injury. In the act of destroying the invader, these cells are killed themselves.
Fig. 2 Neutrophils
	Monocytes (Fig. 3) are produced and then travel around in your blood steam for 5-8 days. Then they move into tissues and are transformed into histiocytes. As histiocytes, they search out invaders and bring them to the lymphocytes. Histiocytes can also kill invaders, although they don’t have as much killing power as neutrophils
Fig. 3 Monocytes
	Lymphocytes (Fig. 4) are responsible for killing viruses and managing the immune system. These cells recognize foreign material and increase body’s resistance to infection. They play a vital role in fighting infection. This means that when a person has fewer white blood cells they are more likely to get an infection.
Fig. 4 Lymphocytes
	Platelets (Fig. 5) make up the third major type of blood cells. They have the job of helping to control bleeding. When you get a cut, the platelets gather to form a plug that will stop the bleeding. When the number of platelets you have is decreased, your risk of bleeding increases, since you have fewer cells helping to control bleeding.
Fig. 5 Platelets
Where are Blood Cells Produced?
	Bone Marrow Blood cells are produced in the bone marrow (Fig. 6), the soft spongy tissue within the bones. New blood cells are called blasts and they either stay in the marrow to mature or else they are sent out to other parts of the body to mature. When a person is healthy, blood cells are produced in an orderly and controlled way, as the body needs them.
Fig. 6 Where blood cells come from.

So what happens when you get leukemia?

In a person with leukemia, abnormal blood cells are produced in mass amounts. Many times these blasts (new blood cells) divide, but generate blasts that cannot function as normal cells. These cells accumulate in the marrow as “islands” or “mounds” of blasts. With leukemia the body makes too many immature or abnormal blood cells and these cells crowd out normal blood cells.

Fig. 7 Blast crises in a person suffering from chronic mylogenous leukemia (picture from CDC Stacy Howard)

Leukemia Cells

Leukemia is a cancer that begins in bone marrow. From there it can spread to other parts of the body, including lymph nodes, brain, liver and spleen. Once a person develops leukemia, they have an abundance of abnormal cells (Fig. 7) that are not equipped to do what normal cells do. A person with leukemia does not have healthy soldiers (white blood cells) which help combat nasty diseases and bacteria that try to enter our body and take over, making us sick. This means that a person who has leukemia is much more likely to be sick and to have high fevers because of infections that their blood cells cannot protect them from.

In a person with leukemia, there are not only fewer white blood cells, but there are also fewer healthy red blood cells and platelets. Anemia is the condition that arises when there are not enough red blood cells to carry oxygen throughout the body. Anemia makes you pale and weak. Furthermore, without the adequate number of platelets, a person bleeds and bruises more frequently.

Classifications of Leukemia

Leukemia is classified as either acute or chronic. In acute leukemia, the bone marrow cells remain immature, and the blasts quickly accumulate because their numbers are increasing. This increase causes rapid progression of the disease—acute leukemia. Chronic leukemia is different in that some blasts are present, but these cells are usually more mature and are still able to carry out normal function. The number of blasts is not increasing as quickly as they do in acute leukemia. Thus, the progression of chronic leukemia is more gradual. The second way that leukemia is classified depends on which blood cells are affected. If the lymphocytes are affected, leukemia is lymphocytic; if the monocyte cells of the bone marrow are affected then it is called myleogenous leukemia.

Four Major Types of Leukemia:

Type	Typical age of onset
Acute lymphocytic leukemia (ALL)	Most common in young children. Also affects adults especially over 65 years old.
Acute myelogenous leukemia (AML)	Occurs in both adults and children.
Chronic lymphocytic leukemia (CLL)	Most often affects adults over 55 years old. Sometimes younger adults. Rarely found in children.
Chronic myelogenous leukemia (CML)	Mainly adults. Very small number of children.

Isaiah had acute myelogenous leukemia, which occurs in both children and adults. Like most leukemia patients, Isaiah was surrounded by doctors and specialists. Together, they decided the best way to combat his cancer. *

Links

Causes

Symptoms

Treatment

Statistics

* This story was adapted from “A Common Pain: Native Families Increasingly Feel the Impact of Cancer.” By Diana Campbell