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In Australia about 2,300 adults and 200 children are diagnosed each year with leukaemia, a cancer of the white blood cells (WBCs). While exposure to radiation, benzene, and some anticancer drugs have been shown to increase the risk of developing leukaemia, and a few cases are associated with genetic disorders or rare viral infections, the cause of most leukaemias is not known.

What is it?

Bone marrow is responsible for the production of blood cells; red blood cells (RBC), platelets, and white blood cells (WBC). The earliest precursors of these are called blasts, which usually mature over several stages before being released into the circulation.

Leukaemia arises when one abnormal blood cell begins to continuously replicate itself. As they accumulate, the production of other normal blood cells are compromised. They might also affect other organs as they spread through the bloodstream.

Leukaemia is classified by how quickly it progresses and the type of WBC involved.

Acute leukaemia

Acute leukaemia is characterised by rapidly progressive disease, typically within days or weeks. It is usually composed of immature cells (blasts). 

Acute myeloid  leukaemia (AML)

  • AML affects predominantly older people but can affect people of all ages
  • It is characterised by production of large numbers of myeloid blasts, with impaired maturation to mature neutrophils, and replace other normal cells in the bone marrow.
Acute promyelocytic leukaemia (APL or APML)
  • APL is an important type of AML associated with a unique genetic abnormality t(15;17) and responds very well to specific types of chemotherapy.
  • The diagnosis must be made urgently as serious clotting and bleeding complications can occur early; treatment must be started as soon as possible.

Acute lymphocytic leukaemia (ALL)

  • ALL is the most common type of leukaemia in children, although it can affect people of all ages.
  • It is characterised by production of either B or T lymphocytes.
Chronic leukaemias

Chronic leukaemia progresses more slowly, typically over several months or years. It tends to be found in older patients and is usually composed of mature cells.

Chronic myelogenous leukaemia (CML)

Mature B-Cell neoplasms

Chronic leukaemia of lymphoid system have many features overlapping with lymphomas. Often, the general term “neoplasm” is used instead. The distinction between the two is generally that the leukaemia signifies the presence of abnormal cells in the peripheral blood, whereas lymphoma signifies predominant involvement in the lymph nodes. Lymphoma is discussed separately (see lymphoma)
  • Chronic lymphocytic leukaemia (CLL) (also known as small lymphocytic lymphoma (SLL)) is the most common leukaemia in Western countries. It consists of a clone of mostly small mature B lymphocytes. A diagnosis can be made by peripheral blood using flow cytometry. A bone marrow biopsy is usually only indicated if treatment is being considered. In some patients CLL progresses so slowly that treatment is never indicated, while in others progression to more aggressive lymphomas could occur. Careful monitoring is usually required. Treatment is commenced only if the patient is symptomatic and/or other bone marrow cell production is affected (e.g. anaemia). 
  • B-cell prolymphocytic leukaemia (B-PLL) is a rare neoplasm of B prolymphocytes affecting the peripheral blood, bone marrow and spleen.
  • Hairy cell leukaemia (HCL) is a rare neoplasm of small mature B-lymphocytes with characteristic “hairy” projections. It is usually very slowly progressive and responds well to specific treatments.
Mature T and NK cell neoplasms
  • T-cell prolymphocytic leukaemia, T-cell large granular lympocytic leukaemia, Aggressive NK cell leukaema and Sezary syndrome are rare neoplasms of the T-cell lineage involving one or more of peripheral blood, bone marrow, lymph nodes, liver, spleen and skin.
  • Many subtypes of T-cell lymphomas (see the section lymphoma for more details).

Last Review Date: December 30, 2018

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