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

Acute leukemia is a rapidly progressing disease that results in the accumulation of immature, functionless cells in the marrow and blood. The marrow often stops producing enough normal red cells, white cells and platelets. Anemia, a deficiency of red cells, develops in virtually all persons with leukemia.

Chronic leukemia progresses more slowly and allows greater numbers of more mature, functional cells to be made.

* Leukemia facts and statistics from Leukemia, Lymphoma, Myeloma, Facts 2009-2010, June 2009.

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New Cases
An estimated 245,225 people in the United States are living with, or are in remission from, leukemia. An estimated 44,790 new cases of leukemia will be diagnosed in the United States in 2009. Chronic leukemias account for 11 percent more cases than acute leukemias. Most cases occur in older adults; the median patient age at diagnosis is 66 years. Leukemia is expected to strike more than 10 times as many adults as children in 2009. (About 44,790 adults compared with 3,509 children, aged 0-14 years). About 33 percent of cancers in children aged 0-14 years are leukemia. The most common cancer in children 1 to 7 years old is acute lymphocytic leukemia (ALL).

The most common types of leukemia in adults are acute myelogenous leukemia (AML), with an estimated 12,810 new cases in 2009, and chronic lymphocytic leukemia (CLL), with about 15,490 new cases this year. Chronic myelogenous leukemia (CML) is estimated to affect about 5,050 persons this year. The most common type of leukemia in children is acute lymphocytic leukemia (ALL), which will account for about 5,760 new cases this year.

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Incidence by Gender
Incidence rates for all types of leukemia are higher among males than among females. In 2009, males are expected to account for more than 57 percent of the new cases of leukemia.

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Incidence by Race and Ethnicity
Leukemia is one of the top 15 most frequently occurring cancers in all races or ethnicities. Leukemia incidence is highest among whites (12.8 per 100,000) and lowest among American Indians/Alaskan natives (7.0 per 100,000), Asian and Pacific Islander populations (7.3 per 100,000)

Although leukemia rates are higher in Americans of European descent than among those of any other race/ethnicity, incidence rates for all types of cancer combined are more than 5 percent higher among Americans of African descent than among those of European descent. The incidence rate for all cancers among African Americans, from 2002 to 2006, was 493.6 per 100,000 individuals, averaging about 190,356 cases each year.

From 1997 to 2006, incidence rates for leukemia have shown the greatest decline in white, Asian and Pacific Islander populations.

Leukemia rates are substantially higher for Hispanic, American Indian/Alaskan natives, white and Asian/Pacific islander children than for African American children. Hispanic children of all races under the age of 20 have the highest rates of leukemia.

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Incidence by Age Group
Leukemia (27.1 percent), neoplasms of the brain and other nervous tissue (16.6 percent), Hodgkin lymphoma (7.2 percent) and NHL (6.6 percent) are the most common types of cancer in children ages 0 to 19 years.

Incidence rates by age differ for each of the leukemias. From 2002 to 2006,  leukemia represented 27 percent of all cancers occurring among children younger than 20 years of age.  It is estimated that in 2009, 3,509 children under the age of 15 will be diagnosed with leukemia throughout the United States. 

From 1975 to 2006, the incidence of AML declined slightly for all age groups. From 2002 to 2006, among 15- to 19-year olds, ALL incidence was approximately twice that of AML. In 25- to 29-year olds, AML incidence was 29 percent higher than that of ALL.

CLL incidence increases significantly among people who are age 50 and older, and AML and CML incidence increase dramatically among people aged 55 years and older. These blood cancers are most prevalent in the seventh, eighth and ninth decades of life.

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Signs and Symptoms
Signs of acute leukemia may include easy bruising or bleeding (as a result of low platelet counts), paleness or easy fatigue (as a result of anemia), recurrent minor infections or poor healing of minor cuts (because of an inadequate white cell count).

These symptoms and signs are not specific to leukemia and may be caused by other more common conditions. They do, however, warrant medical evaluation. A proportion of people with chronic leukemia may not have major symptoms and are diagnosed during a routine medical examination. The diagnosis of leukemia requires specific blood tests, including an examination of cells in the blood and marrow.

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Possible Causes
Anyone can get leukemia. Leukemia affects males and females of all ages. The cause of leukemia is not known. Chronic exposure to benzene in the workplace, exposure to extraordinary doses of radiation, and certain cancer therapies, can be causes of the disease, although most cases are not explained by any of these causes.

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Treatment
The aim of treatment is to bring about a complete remission. Complete remission means that there is no evidence of the disease and the person returns to good health with normal blood and marrow cells. Relapse indicates a return of the cancer cells and return of other signs and symptoms of the disease. For acute leukemia, a complete remission (no evidence of disease in the blood or marrow) that lasts five years after diagnosis often indicates long-term survival. Treatment centers report increasing numbers of patients with leukemia who are in complete remission at least five years after the diagnosis of their disease.

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Survival
The five-year relative survival rate has nearly quadrupled in the past 48 years for patients with leukemia. From 1960 to 1963, the five-year relative survival rate among Americans of European descent with leukemia was 14 percent.  From 1975 to 1977, the five-year relative survival rate for all persons with leukemia jumped to 35 percent, and from 1999 to 2005 the overall relative survival rate was 54 percent. The relative survival rates differ by the person's age at diagnosis, gender, race and the type of leukemia.

From 1999 to 2005, the five-year relative survival rates overall** were:

Currently, there are approximately 245,225 people living with leukemia in the United States.

** Treatment outcomes vary, even among patients with the same diagnosis. Individuals are encouraged to talk to their physicians for more information.  In addition, these statistics may underestimate survival to a degree because they may be based on data that does not include outcomes of treatment with the most current options available. Newer agents and drug combinations, progress in stem cell transplantation, better supportive care and studies of new drugs in clinical trials are all contributing to improved outcomes and quality of life for people diagnosed with blood cancers.

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Deaths
It is anticipated that approximately 21,870 deaths in the United States will be attributed to leukemia in 2009 (12,590 males and 9,280 females). The highest rate of deaths from 2002 to 2006 was in whites (7.5 per 100,000), followed by African Americans (6.4 per 100,000).

In 2009, there will be an estimated 4,390 deaths from CLL and 1,400 deaths from ALL. There will be an estimated 9,000 deaths from AML and 470 deaths from CML in this year. Unclassified forms of leukemia will account for 6,610 additional deaths.

In 2009, in the United States, leukemia will be the fifth most common cause of cancer deaths in men and the seventh most common in women. The estimated numbers of deaths attributed to leukemia in the United States is about 36 percent higher for males than females.

Between 2002 to 2006, African Americans who were diagnosed with leukemia between the ages of 25 and 64 had a higher death rate than whites from the disease. In 2009, approximately 1,830 African Americans (970 males and 860 females) are expected to die of leukemia. Leukemia is the seventh most common cause of cancer deaths in African-American males and the eighth most common in African-American females.

The leukemia death rate for children 0 to 14 years of age in the United States has declined 88 percent from 1969 to 2006. Despite this decline, leukemia causes more deaths than any other cancer among children and young adults under age 20. About 460 children under the age of 15 are expected to die from leukemia in 2009.

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Get More Information
Further information on treatment and supportive care can be obtained from the free LLS informational booklets on the different types of leukemia. Click here to view, print or order free LLS publications .

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Contact Us
The Leukemia & Lymphoma Society Home Office
1311 Mamaroneck Ave.
White Plains, NY 10605

or call the Information Resource Center at (800) 955-4572.