Leukemia

What is leukemia?

Leukemia is a term used to refer to a group of cancers that affects the blood and bone marrow (the soft spongy tissue inside bones where blood cells are produced). Leukemias are a very heterogeneous group of blood cancers and they differ from one another in the underlying cause or pathway of development, prognosis and responsiveness to treatment. There are several dozens, if not hundreds, of different types of leukemia.

What are the types of leukemia?

Leukemias are broadly classified based on the duration and progression of symptoms into 2 groups: acute leukemias and chronic leukemias. Acute leukemias develop rapidly and if left untreated can lead to death in weeks or months whereas chronic leukemias develop less rapidly and if left untreated can lead to death in months or years.

Under each broad group, leukemias are further classified based on the marrow cell it develops from, into 2 major subgroups: myeloid (from marrow cells that form red cells, platelets and some types of white cells called granulocytes) and lymphoid (from marrow cells that form some white cells that are part of the immune system). Thus, largely, there are four main types and commonest forms of leukemia: acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), chronic myeloid leukemia (CML) and chronic lymphocytic leukemia (CLL).

How does leukemia develop?

Leukemia begins in a cell in the bone marrow. The cell undergoes a change and becomes a type of leukemia cell. Once the marrow cell undergoes a leukemic change, the leukemia cells may grow and survive better than normal cells. Over time, the leukemia cells crowd out or suppress the development of normal cells. The rate at which leukemia progresses and how the cells replace the normal blood and marrow cells are different with each type of leukemia.

In acute leukemias, the cell that develops into the leukemia cell is an immature cell that has not yet differentiated into a mature cell and is therefore able to progress rapidly and replace the normal blood and marrow cells. Acute leukemias are characterized by a defect in maturation, leading to an imbalance between proliferation and maturation; since cells of the leukemic clone continue to proliferate without maturing to end cells and dying, there is continued expansion of the leukemic clone and immature cells predominate.

What causes leukemia?

Like most cancers, the cause of leukemia is largely unknown. However, some leukemias have been shown to be associated with a number of factors. Genetic, environmental (exposure to chemicals or radiation), infections (viruses, bacteria, parasite), previous treatment for other conditions with medications that are toxic to the bone marrow cells (chemotherapy for other cancers or cytotoxic drugs for autoimmune disorders).

What are the symptoms of leukemia?

The symptoms depends on the cell line affected by the leukemia. Usually the production of the red cells are affected and the individual will come down with symptoms of anemia (fatigue, shortness of breath). The white cells are also frequently affected, therefore the person will come down with fever due to infections but there may also be fever in the absence of infection due to increased body metabolism. Other features of increased metabolism may also be present, such as weight loss and excessive night sweats. If the platelets are affected, the person could present with bleeding and easy bruising.

Other features of leukemias are from infiltration of organs of the body such as the spleen and the liver which becomes enlarged or into lymph nodes (tiny bean-shaped organs located throughout the body where some immune cells called lymphocytes that help fight infection stay) leading to swelling in the neck, armpits or groin.

How are leukemias diagnosed?

Usually a screening test of checking the complete (full) blood count is done first. This may show a low hemoglobin level (anemia) and/or low platelet count (thrombocytopenia). The blood count in most leukemias show an elevated white cell count but occasionally may be lower than the expected normal range. This abnormal cells are flagged by the machine and prompt the need to view the cells under the microscope.

Most times the leukemia cells are detected in the blood film and then the patient should immediately be referred to a hematologist (a specialist trained in the management of blood conditions) who will assess the patient, order the appropriate investigations to confirm the diagnosis such as bone marrow aspiration and biopsy, other routine and special blood tests, appropriate imaging test (x-rays, ultrasound scans, CT scans) and commence appropriate treatment as soon as possible.

How is leukemia treated?

The treatment of leukemias are quite varied. This underlies the need for accurate diagnosis prior to treatment. The treatment range from no treatment at all for some types of leukemia at the initial stage such as chronic lymphocytic leukemia, to a wide range of medications used for other various types of leukemia. Treatment is usually in the form of chemotherapy and immunotherapy. Occasionally radiotherapy is also used.

The treatment of acute leukemia is usually in phases. The initial intensive treatment is given to achieve what is called remission. Remission is when there are no detectable leukemia cells. This is usually followed by consolidation phase to ensure that the disease does not resurface. Subsequently maintenance treatment can be given to ensure that it remains as it is. For some types of leukemia, stem cell transplantation is mandatory to achieve a complete cure and reduce the risk of relapse. If there is a relapse of the leukemia, additional treatment can be given and then a stem cell transplantation is done after achieving another remission.

For the chronic leukemias, the treatment is usually in cycles with the aim to achieve a state of remission. The treatment of chronic leukemia involves the use of drugs that specifically target the leukemic cells. Most times remission is achieved with the medications and a stem cell transplantation is not usually required.

Can leukemia be cured?

Most acute leukemias and some chronic leukemia can be completely cured. However, because of the possibility of a relapse, it is important to ensure that the treatment is completed and that it destroys the last leukemia cells.

The educational videos are from https://know-aml.com/en/get-involved/resources?language=en

To learn more about specific leukemias, check out the links below for more excellent information resources

https://www.lls.org/leukemia