Leukemia is a type of cancer that affects the blood and bone marrow, where blood cells are formed. All types of leukemia cause rapid, uncontrolled growth of abnormal bone marrow and blood cells.
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The main differences between the types include how fast the disease progresses and the types of cells it affects.
There are four main types of leukemia, which we describe in detail below:
- acute lymphocytic leukemia (ALL)
- acute myeloid, or myelogenous, leukemia (AML)
- chronic lymphocytic leukemia (CLL)
- chronic myeloid, or myelogenous, leukemia (CML)
Lymphocytic leukemia affects the lymphocytes, a type of white blood cell. Myeloid leukemia can affect the white blood cells, red blood cells, and platelets.
According to the National Cancer Institute, roughly
In this article, explore the four main types, their symptoms, the treatment options available, and the outlook.
The full name of this type of cancer is acute lymphocytic leukemia, and “acute” means that it
The disease starts in the bone marrow, which produces stem cells that develop into red and white blood cells and platelets.
In a healthy person, the bone marrow does not release these cells until they are fully developed. In someone with ALL, the bone marrow releases large quantities of underdeveloped white blood cells.
There are
One subtype is B-cell ALL. This begins in the B lymphocytes, and it is the most common form of ALL in children.
Another subtype is T-cell ALL. It can cause the thymus, a small organ at the front of the windpipe, to become enlarged, which can lead to breathing difficulties.
Overall, because ALL progresses quickly, swift medical intervention is key.
What causes it?
As
- benzene
- ionizing radiation
- certain viral infections
- chemotherapy or radiotherapy
Although genetic factors may play a role, ALL is not a familial disease.
Who does it affect?
ALL is the most common form of leukemia in children.
The risk of developing it is
Symptoms
ALL symptoms can be nonspecific — difficult to distinguish from those of other illnesses.
They may
- night sweats
- easy bruising
- pale skin
- swollen lymph nodes
- enlarged testicles
- weakness
- unexplained weight loss
- a low urine output
- bone pain
- changes in thinking and mood
- difficulty breathing
In a person with AML, the bone marrow makes abnormal versions of platelets, red blood cells, and white blood cells called myeloblasts.
The full name of this disease is acute myeloid leukemia, and “acute” refers to the fact that it is fast-growing.
It
- Myeloblasts: These typically form granulocytes, another type of white blood cell.
- Monoblasts: These typically turn into white blood cells called monocytes or macrophages.
- Erythroblasts: These turn into red blood cells.
- Megakaryoblasts: These typically turn into the cells that make platelets.
Doctors classify AML by subtype, depending on:
- the type of bone marrow cell that the cancer began in and the maturity of the cells
- whether the cells have chromosomal or genetic changes
- whether the leukemia is related to previous cancer treatment
- in children with AML, whether they also have Down syndrome
AML can be difficult to treat and requires prompt medical attention.
What causes it?
The
Other factors that increase the risk of developing AML include:
- aplastic anemia
- Down syndrome
- Bloom syndrome, a genetic condition
- exposure to radiation
- exposure to tobacco smoke
- exposure to benzene
- previous exposure to chemotherapy
Who does it affect?
Most people who develop AML are
It is also the second most common form of leukemia in children.
Symptoms
Symptoms of AML can vary and may include:
CLL is the most common form of leukemia among adults in the U.S. and other Western countries.
There are two types. One progresses slowly, and it causes the body to have high levels of characteristic lymphocytes, but only slightly low levels of healthy red blood cells, platelets, and neutrophils.
The other type progresses more quickly and causes a significant reduction in levels of all healthy blood cells.
In someone with CLL, the lymphocytes often look fully formed but are less able to fight infection than healthy white blood cells. The lymphocytes tend to build up very slowly, so a person might have CLL for a long time before experiencing symptoms.
What causes it?
Genetic factors are the
- radiation exposure
- tobacco use
- benzene exposure
Who does it affect?
CLL
Symptoms
CLL typically causes no early symptoms. When symptoms are present, they may
- a fever higher than 100ºF that lasts more than 2 weeks, with no other sign of infection
- night sweats, with no sign of infection
- extreme fatigue
- low appetite
- unexplained weight loss
Also, 50–90% of people with CLL have swollen lymph nodes.
CML is a slow-growing type of leukemia that develops in the bone marrow.
The full name of CML is chronic myeloid leukemia. As the
These leukemia cells then grow, divide, and enter the blood.
What causes it?
CML occurs due to a rearrangement of genetic material between the chromosomes 9 and 22.
This rearrangement fuses a part of the ABL1 gene from chromosome 9 with the BCR gene from chromosome 22, called the Philadelphia chromosome. The result of this fusion is called BCR-ABL1.
BCR-ABL1 produces a protein that promotes cell division and stops apoptosis, the process of cell death, which typically removes unneeded or damaged cells.
The cells keep dividing and do not self-destruct, resulting in an overproduction of abnormal cells and a lack of healthy blood cells.
This occurs during the person’s lifetime and is not inherited.
Who does it affect?
CML typically affects adults. People aged 65 and older make up
Symptoms
The symptoms of CML are unclear, but they may
- weakness
- fatigue
- night sweats
- feeling full quickly after eating a small amount
- weight loss
- a fever
- bone pain
The symptoms may vary, depending on the type of leukemia. Overall, a person should get in touch with a doctor if they experience:
- fatigue
- weakness
- bruising or bleeding easily
- pale skin
- swollen lymph nodes
- a swollen abdomen
- a fever
- chills
- more frequent or heavier periods than usual
- swollen or bleeding gums
- lightheadedness
- weight loss
- night sweats
- frequent infections
- pain in bones and joints
Treatment for ALL typically involves
Treatment for AML involves the first two phases. The induction phase may include treatment with the chemotherapy drugs cytarabine (Cytosar-U) and daunorubicin (Cerubidine) or idarubicin (Idamycin). The doctor may also recommend targeted drugs.
Induction
The goal of this phase is to kill the leukemia cells, causing the cancer to go into remission, using chemotherapy.
The doctor may recommend:
- vincristine (Oncovin)
- dexamethasone (Neofordex)
- prednisone (Deltasone)
- doxorubicin (Caelyx)
- daunorubicin (Cerubidine)
People having chemotherapy may need to see their doctors frequently and spend time in the hospital, due to the risk of serious infections and complications.
This phase of the treatment lasts for about 1 month.
Consolidation
Even if the treatment so far has led to remission, cancer cells may be hiding in the body, so more treatment is necessary.
The consolidation phase may involve taking high doses of chemotherapy. A doctor may also recommend targeted drugs or stem cell transplants.
Maintenance
This phase, consisting of ongoing chemotherapy treatments, usually lasts for 2 years.
Since CLL tends to progress slowly, and its treatment can have unpleasant side effects,
For a person with CML, the focus is
Overall, the initial treatment tends to include monoclonal antibodies, targeted drugs, and chemotherapy.
If the only concern is an enlarged spleen or swollen lymph nodes, the person may receive radiation or surgery.
If there are high numbers of CLL cells, the doctor may suggest leukapheresis, a treatment that lowers the person’s blood count. This is only effective for a short time, but it allows the chemotherapy to start working.
For people with high-risk disease, doctors may recommend stem cell transplants.
A person’s prognosis depends on the type of leukemia.
Learn more about survival rates for people with leukemia here.
ALL
About 80–90% of adults with ALL experience complete remission for a while during treatment. And with treatment, most children recover from the disease.
Relapses are common in adults, so the overall cure rate is
AML
The older a person is when they receive an AML diagnosis, the more difficult it is to treat.
More than
CLL
A person may live for a
Treatments can help keep the symptoms under control and prevent the disease from spreading. However, there is no cure.
CML
Stem cell transplants can cure CML. However, this treatment is very invasive and is not suitable for most people with CML.
The United Kingdom’s National Health Service estimate that 70% of males and 75% of females live for at least 5 years after receiving a CML diagnosis.
The earlier a person receives the diagnosis, the better their outlook.
Leukemia is a type of cancer that affects the blood and bone marrow. It can affect people of all ages.
There are four main types of leukemia. They differ based on how quickly they progress and the types of cells they affect.
Treatments for all types of leukemia continue to improve, helping people live longer and more fully with this condition.