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Types of Cancer > Leukemia > Leukemia-- Acute Lymphocytic Leukemia (ALL) > Overview

Acute Lymphoid Leukemia (ALL)

Carolyn Vachani, RN, MSN, AOCN
Affiliation: The Abramson Cancer Center of the University of Pennsylvania
Last Modified: January 16, 2008

This article is a more specific discussion of ALL. Please be sure to read Leukemia: the Basics first, so you have an understanding of leukemia in general.

What is ALL?

ALL is a blood cancer that affects the white blood cells. There are two main types of white blood cells, lymphocytes (affected by ALL) and myelocytes (affected by AML). Lymphocytes are further broken down into B and T cell lymphocytes. ALL is a spectrum of disease comprised of several different subtypes, named for the cell type that is affected (B or T) and how abnormal the cell appears under a microscope. A person with ALL develops abnormal numbers of white blood cells rather quickly, giving the disease the name “acute”.

The white blood cell (WBC) count may be higher or lower than normal, but the WBCs that are being produced are immature and do not function well. Because WBCs are an important part of fighting infections, patients often have multiple infections that don’t respond to treatment before they are diagnosed. Some people will have low red blood cell or platelet counts because the overpopulation of WBCs crowds out these cells.

There will be an estimated 5000 new cases of ALL diagnosed in 2007 in the United States, and two thirds of these cases will be in children. ALL accounts for 1-2% of all adult cancer cases (and 20% of adult leukemia cases), but makes up 25% of all childhood cancers (all types). ALL can occur at any age, but is most common in children, ages 2 to 4, and adults over age 50. This article will address ALL in adults.

What causes ALL?

In most cases, the cause of ALL is unknown. There are some factors that are known to increase a person’s risk of developing ALL, including previous treatment with chemotherapy or radiation therapy, exposure to large amounts of radiation (such as an atomic bomb), or the presence of a genetic disorder (i.e. Down’s syndrome, Klinefelter’s syndrome). Research has identified viruses, such as Epstein-Barr, HTLV1, and HIV, as potential causes in some cases.