Leukemia

Leukemia: The Facts

What is it?

Leukemia is the term used for cancer that affects the blood cells. Normal, healthy blood is made up of fluid called plasma and three types of blood cells. White blood cells fight infection and disease. Red blood cells carry oxygen and carbon dioxide to and from the cells of the body. And platelets (also called thrombocytes) help form blood clots to control bleeding. Blood cells are made in the bone marrow, the soft, spongy middle part of the bones. In adults, most bone marrow can be found in the hips, ribs, spine, and skull. The immature blood cells in the marrow are called blasts.

When Leukemia develops, the body produces large numbers of abnormal blood cells. In most types of Leukemia, the abnormal cells are white blood cells. The Leukemia cells usually look different from normal blood cells and they do not function properly. Often, these abnormal blood cells are immature blasts that cannot grow into healthy blood cells.

There are two kinds of abnormal white blood cells that cause Leukemia. If the cancer cells are lymphoid, the disease is called Lymphocytic Leukemia. If they are myeloid cells, the disease is Myelogenous Leukemia. Leukemia may also be acute or chronic. Acute Leukemia cancer cells are immature blasts and grow quickly, while Chronic Leukemia cells are a combination of immature and mature cells, and grow more slowly. There are six types of Leukemia, which doctors usually identify according to their growth speed (acute or chronic), and the cancer cell type (lymphocytic or myelogenous):

o Acute Lymphocytic Leukemia (ALL): This type of Leukemia is the most common Leukemia found in children, and some cases are adults over the age of 65. Very few cases of ALL are adults age 20-65.

o Acute Myelogenous Leukemia (AML): This type of Leukemia almost always affects adults and is rarely seen in children. It is also called Acute Non-Lymphocytic Leukemia (ANLL).

o Chronic Lymphocytic Leukemia (CLL): This Leukemia usually affects adults over age 55, and sometimes is found in younger adults, but it almost never affects children.

o Chronic Myelogenous Leukemia (CML): This Leukemia almost always affects adults and is extremely rare in children.

o Hairy Cell and Acute Promyelocytic Leukemia: These two forms of Leukemia are extremely rare in both adults and children.

Who gets it?

Adult Leukemia

This year it is predicted that 30,000 people will be diagnosed with Leukemia in the United States. Twenty-seven thousand of those cases will be adult Leukemia. Leukemia is one of the ten most common types of cancer diagnosed, and there seems to be a slightly higher occurrence in men than in women. African Americans are only half as likely to get ALL as Caucasians, but are just as likely to get AML.

Childhood Leukemia

Leukemia is the most common cancer diagnosed among children and young adults, equal to one third of all cases of cancer in children under 15 years old, and one fourth of all cancer cases in patients under 20. This year, 2600 children will be diagnosed with Leukemia, 70% with ALL and the rest with AML. Chronic Leukemia is very rare among children. Most childhood Leukemia patients are diagnosed between the ages of 2 and 3 years old. As with adults, ALL is more common among Caucasian children, but AML is equally common among Caucasian and African-American children.

Risk Factors

There are some factors which could place you at a higher risk for Leukemia, including:

• Smoking-20% of all cases of AML are caused by smoking.
• Environmental Factors-

-Exposure to dangerous chemicals such as benzene and those used in the rubber and shoe industries.

-Exposure to very high amounts of radiation such as from an atomic bomb or a nuclear reactor accident.

-Anti-cancer drugs such as those used in chemotherapy for other cancers can increase the risk of getting Leukemia. However, the benefits of these drugs far outweigh such risks.

• Rare Diseases-People with rare genetic diseases such as Down’s Syndrome, Ataxia Telangienctasia, and Bloom’s Syndrome, are at higher risk for getting Leukemia.
• Family History of Leukemia.

How is it detected?

There is no set screening test as yet for Leukemia in children or adults. For the most part, doctors learn that a patient may have Leukemia during routine blood tests such as those for employment, military service, pregnancy, and before surgery. The best strategy for early detection in children is prompt attention to the signs and symptoms of this disease. In order to diagnose Leukemia, the physician will do a full physical exam, feeling especially for swelling of the liver and spleen, and enlarged lymph nodes. The doctor may also ask about a patient’s family medical history of Leukemia. Several tests can be performed to detect Leukemia:

• Bone Marrow Samples are taken with a needle, usually from the hip, along with a small piece of the bone. The marrow and bone are then examined in a lab for the abnormal Leukemia cells.
• A Lumbar Puncture or Spinal Tap is a sample of spinal fluid that can be examined to determine if Leukemia cells have reached the spinal cord and brain.
• X-rays or a CT Scan of the chest, abdomen, and pelvis can show whether or not the disease has spread to these areas.
• Chromosome Analysis may show certain genetic changes that are associated with Leukemia.

The doctor will then decide, based on the test results, what type of Leukemia is present. Each type of Leukemia is then divided into either stages (depending on the seriousness of the disease) or subtypes (depending on the different kinds of cells involved). The following system was developed by a group of physicians from France, America, and Britain, and is therefore called the FAB System:

• AML is diagnosed as subtype M0, M1, M2, M3, M4, M5, M6, or M7. Each of these types leaves certain chemicals in the blood called marker molecules.
• ALL is diagnosed according to stages L1, L2, and L3, with L3 being the most serious form of the disease.
• CML is diagnosed in three stages depending on the number of immature blasts in the blood.

-Chronic CML: less than 5% blasts, mild symptoms, responds well to treatments.

-Accelerated CML: 5-30% blasts, fever, loss of appetite and weight loss, not as responsive to treatment.

-Blast CML (also Acute, Blast Crisis): more than 30% blasts, fast growing and aggressive disease.

• CLL is diagnosed in stages 0-4, with 4 being most serious, according to the Rai System. (The Rai system is a staging system that separates CLL into low-risk, intermediate-risk, and high-risk categories.)

Symptoms

There are many symptoms of Leukemia, but none are specific (definitely indicating) to Leukemia:

• Chronic infections
• Anemia-red blood cells are unhealthy
• Easy bruising or bleeding
• Fever with chills and sweating
• Weakness/Fatigue
• Loss of appetite
• Weight loss
• Swelling of liver, spleen, or lymph nodes
• Petechiae-tiny pinpoint red spots under the skin
• Sore or bleeding gums
• Pain in bones or joints
• Shortness of breath, coughing, chest pains

In cases of ALL that has spread to the brain or spine, the following symptoms may also be present:

• Headaches
• Vomiting
• Loss of muscle control
• Weakness of legs and arms
• Seizures

Is it curable?

Many strides have been made in Leukemia treatment since the 1950s. The current five-year survival rate for all Leukemia in general for patients of all ages is 43%. However, each individual type of Leukemia is different. ALL has the highest survival rate of all four types, since most of the advances in treatment have been made in ALL treatment. In RI, the death rates for both men and women are approximately equal to the national averages, and continue to decrease.

There have been especially great advances in the treatment of childhood ALL. Childhood Acute Lymphocytic Leukemia responds better to chemotherapy treatments than other types of Leukemia because the cells of the disease grow quickly and chemotherapy drugs target fast growing cells. The five-year survival rate for Childhood ALL is now over 80%. Survival rates for Childhood AML remains at about 40%.

It is easier to prevent cancer than to cure it…

Although many of the factors that cause Leukemia are out of your personal control, certain lifestyle changes and habits can help to reduce your risk of getting Leukemia and other cancers, or help detect Leukemia early:

o Don’t smoke.

o Avoid dangerous chemicals such as benzene.

o Avoid being exposed to large amounts of radiation.

o Have a regular blood workup when you visit your doctor.