General | June 22, 2015 | Author: The Super Pharmacist
Leukaemia is a cancer of cells in the blood marrow (cells that develop into blood cells). Cancer cells from the bone marrow spread out into the bloodstream, with most types of leukaemia arising from cells that normally develop into white blood cells (the word leukaemia is derived from a Greek word meaning ‘white blood’). There are a number of different types of leukaemia, each with their own prognosis and treatment regimen.
There are four main types of leukaemia: Leukaemia is typically classified according to its form and speed at which it progresses. Acute refers to leukaemia that develops and progresses quickly over a short period of time, whereas chronic leukaemia develops and progresses slowly. Lymphoblastic and Lymphocytic is a reference to abnormal cancerous cells that originated from a lymphoid stem cell, and myeloid is a reference to abnormal cancerous cells that originated from a myeloid stem cell. Each category of leukaemia has various subtypes.
Acute lymphoblastic leukaemia (ALL) predominantly affects children, and is the most common childhood leukaemia globally. Treated with chemotherapy or radiotherapy, survival rates vary by age group, with 85% survival rates in children and around 50% in adults (1). In adults, ALL typically affects those over the age of 65 and it includes a number of subtypes such as Birkitt’s leukaemia and acute biphenotypic leukaemia.
Chronic lymphocytic leukaemia (CLL) typically affects adults over the age of 55 and is very rare in children. It is an incurable form of leukaemia, although there are many effective treatment methods and there is a five year survival rate of 75% (2).
Acute myeloid leukaemia (AML) is more common in adults, and more prevalent in men than women. It is treated with chemotherapy and has a survival rate of 40%, although its subtype Acute Promyelocytic Leukaemia (APL) has a survival rate in excess of 90% (3).
Chronic myeloid leukaemia (CML) predominantly affects adults and has a five year survival rate of 90% (4).
The majority of leukaemia cases are typically treated with a multi-drug chemotherapy regimen, or radiotherapy. In the case of some leukaemias, a bone marrow transplant may also be effective. Types of treatment will depend on a range of personal factors and the acute or chronic nature of the leukaemia that is being treated.
ALL treatment predominantly focuses on the management of bone marrow and whole body disease, preventing leukemic cells from spreading to other parts of the body. Treatment for ALL is split into a number of stages: Induction chemotherapy is the catalyst for bone marrow remission and attempts to kill most leukaemia cells, with multi-drug therapies such as prednisone, vincristine and an anthracycline drug typically used in adults (5). Other drugs, such as cyclophosphamide and L-asparaginase, are also occasionally used in induction plans, which typically last between 4-6 weeks (6). In the Consolidation (Intensification) phase, further intensive treatment is given to rid the body of all remaining leukaemia cells. A number of clinical approaches are often used, but most commonly this phase is characterised by high-dose medication that is undertaken for several months. The next phase, known as maintenance therapy, is less intensive than induction and consolidation and its aim is to kill any remaining cells that have survived the previous two phases. It can last for anywhere up to two years typically, with lower doses of chemotherapeutic drugs used during treatment (7).
CLL treatment is dependent on its severity. This is measured in three stages: Stage A (there are fewer than three areas in the body that have swollen lymph glands), Stage B (three or more areas in the body with swollen lymph glands), and Stage C (a low number of red blood cells, platelets, or both). Many people in Stage A will not require treatment, as the risks often outweigh the benefits. In this instance, individuals in Stage A will be carefully monitored on a regular basis to ensure that it doesn’t progress to Stage B or Stage C (8). As CLL cannot be cured, all treatment options aim to maintain very low levels of abnormal lymphocytes, ensuring patients remain in remission and allows the bone marrow to function normally. CLL chemotherapy is often taken orally, and occasionally given as an injection. A relatively new treatment known as monoclonal antibodies are small proteins that attach to abnormal lymphocytes, destroying them without harming other cells(9). This treatment method can also be used alongside traditional methods of chemotherapy, and radiotherapy can also be used to reduce the size of enlarged spleens or lymph nodes (10).
AML treatment is varied, although the predominant treatment option is chemotherapy, similar to that used in ALL. Additionally, individuals with the APL subtype of AML are also usually offered all-trans retinoic acid (ATRA), a specialised form of Vitamin A. It is usually administered for approximately three months, and its pharmaceutical purpose is to help make leukaemia cells differentiate and in the process rapidly improve leukaemia symptoms. Additionally, a stem cell transplant (SCT), also sometimes known as a bone marrow transplant, is occasionally used in patients classified as high risk or where patients have relapsed following previous rounds of chemotherapy (11). Outcomes for patients have historically been poor, although improvements have been made as a result of recent pharmacological developments. However, the prognosis for patients over 60 with AML remains poor due to the intensive nature of the chemotherapy and its effect on the body. As many older patients have also had previous bone marrow problems, their ability to respond well to treatment can also be severely compromised.
Most treatments of CML are not curative but can keep the condition under control for a number of years when managed appropriately. A number of treatments are often offered in isolation or combination, depending on the stage and severity of CML and individual responsiveness to particular drugs. Tyrosine kinase inhibitor medicines can be administered to block the growth of abnormal cells, and interferon alpha has also been evidenced to help the immune system fight off abnormal leukaemia cells (12). Chemotherapy treatment is also available, as is a stem cell transplant that is most commonly used among younger adults with CML.
Hutter JJ (2010) Childhood leukaemia Paed in Review 31(6):234-41
1. World Cancer Report 2014 World Health Organization Available online at http://apps.who.int/bookorders/anglais/detart1.jsp?codlan=1&codcol=80&codcch=275 (last accessed 10th May 2015)
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11. Talpaz M, Mercer J, Hehlmann R (2015) The interfon-alpha revival in CML Ann Hematol 94(2):195-207