Leukemia is a malignant disease (cancer) of the bone marrow and blood. It is characterized by the uncontrolled accumulation of blood cells. Leukemia is divided into four categories: 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 Lymphocytic Leukemia
• Chronic Lymphocytic Leukemia
• Acute Myelogenous Leukemia
• Chronic Myelogenous Leukemia

Acute leukemia is a rapidly progressing disease that results in the accumulation of immature, functionless cells in the marrow and blood. The marrow often can no longer produce enough normal red blood cells, white blood cells and platelets. Anemia, a deficiency of red cells, develops in virtually all leukemia patients. The lack of normal white cells impairs the body's ability to fight infections. A shortage of platelets results in bruising and easy bleeding.

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

Among an estimated 30,600 new cases of leukemia in the United States this year, about equal proportions are acute leukemia and chronic types. Most cases occur in older adults; more than half of all cases occur after age 64. Leukemia is expected to strike 8 times as many adults as children in 2003. (About 27,815 adults compared with 3,441 children, ages 0-19). About 30 percent of cancers in children ages 0-14 years are leukemia. The most common form of leukemia among children under 19 years of age is Acute Lymphocytic Leukemia (ALL).

Lymphoma is a general term for a group of cancers that originate in the lymphatic system. The lymphomas are divided into two major categories: Hodgkin lymphoma and all other lymphomas, called non-Hodgkin lymphomas. Hodgkin lymphoma was named for Thomas Hodgkin, an English physician who described several cases of the disease in 1832. Hodgkin lymphoma represents about 12.5 percent of all lymphomas.

Each year, 61,000 persons in the United States learn they have lymphoma. This figure includes approximately 7,600 new cases of Hodgkin lymphoma and 53,400 new cases of non-Hodgkin lymphoma (abbreviated as NHL).

Lymphomas are cancers that begin by the malignant transformation of a lymphocyte in the lymphatic system. The prefix "lymph-" indicates their origin in the malignant change of a lymphocyte and the suffix "-oma" is derived from the Greek word meaning "tumor".

Lymphomas, including Hodgkin lymphoma, result from an acquired injury to the DNA of a lymphocyte. Scientists know that the damage to the DNA occurs after birth and, therefore, is acquired rather than inherited. The change or mutation of DNA in one lymphocyte produces a malignant transformation. This mutation results in the uncontrolled and excessive growth of the lymphocyte, and confers a survival advantage on the malignant lymphocyte and the cells that are formed from its multiplication. The accumulation of these dividing cells results in the tumor masses in lymph nodes and other sites.

Lymphomas generally start in lymph nodes or collections of lymphatic tissue in organs like the stomach or intestines. Lymphomas may involve the marrow and the blood in some cases. Spread from a lymphoma site is not unexpected. Lymphocytic leukemias originate and are most prominent in the marrow and spill over into the blood. They occasionally spread to involve the lymph nodes

Treatments

Treatment options for blood-related cancers include radiation therapy, chemotherapy, and blood and marrow stem cell transplantation. A description of these and other cutting edge therapies can be found at the Society's website.