Leukemia: Types, Causes, Symptoms, Diagnosis, and Treatment
Leukemia is a type of blood cancer characterized by an abnormal increase of white blood cells in the body. It starts in the bone marrow, the soft tissue inside most bones, and can spread to other parts of the body, such as the lymph nodes, spleen, brain, liver, and central nervous system. This disease can affect both men and women, and can occur in people of any age.
Each year, about 440,000 new cases of leukemia in the world along with 310,000 deaths due to the cancer. There are around 60,000 new cases of leukemia in the U.S. in 2020, and over 23,000 related deaths, according to the American Cancer Society.
Types of Leukemia
Leukemia is categorized into four types based on which type of white blood cell is involved – lymphocytes or myeloid cells – and how fast it progresses – very quickly (acute) or slowly over time (chronic).
Acute lymphocytic leukemia (ALL)
Acute lymphocytic leukemia, also called acute lymphoblastic leukemia, is a type of blood cancer that starts from white blood cells called lymphocytes in the bone marrow.
The lymphocytes normally fight infection. With acute lymphocytic leukemia, the bone marrow makes too many immature white blood cells, overtaking the space there. This prevents the bone marrow from making the normal blood cells that are needed for fighting infection and delivering oxygen to all the cells of your body.
ALL usually develops quickly over days or weeks. It is the most common form of leukemia in children, but it can also affect adults.
Chronic lymphocytic leukemia (CLL)
Chronic lymphocytic leukemia is a blood cancer that affects the lymphocytes and tends to progress slowly over many years. This leukemic cells start in the bone marrow but then go into the blood.
CLL usually develops slowly over months and years. CLL is the second most common type of leukemia in adults. It often occurs during or after middle age and is rare in children.
Acute myeloid leukemia (AML)
Acute myeloid leukemia, also known as acute myelogenous leukemia or acute myeloblastic leukemia, is a type of blood cancer that starts from white blood cells called granulocytes in the bone marrow.
In AML, the bone marrow produces granulocytes too quickly because they grow and divide too fast. These abnormal cells build up in the blood and bone marrow.
The leukemic cells can eventually spread to other parts of the body, including the lymph nodes and the spleen. If it wasn’t treated the leukemia would cause death within a few weeks or months. But treatments work very well for most people with AML.
Acute myeloid leukemia is most common in older people over the age of 75, though it can occur at any age.
Chronic myeloid leukemia (CML)
Chronic myeloid leukemia (CML) is a type of cancer that affects the blood and bone marrow.
In CML, the bone marrow produces too many myeloid cells – immature white blood cells that are not fully developed and do not work properly.
These cells gradually crowd the bone marrow, interfering with normal blood cell production. Over time, a shortage of red blood cells and platelets can cause anemia, bleeding or bruising.
CML usually develops gradually during the early stages of disease, and progresses slowly over weeks or months. It can occur at any age, but is most common in older adults around 60-65 years of age.
Leukemia Causes and Risk Factors
The exact causes of leukemia are not yet clearly identified. However, there are some factors that can make a person more likely to develop any form of leukemia.
Smoking cigarettes increases the risk of developing acute myeloid leukemia.
- Having a family history of leukemia
You have a greater risk if you have a close family member (parent or sibling) who had leukemia.
- Exposure to high levels of radiation
Exposure to a high level of radiation, such as from radiation therapy or an atomic blast, can lead to acute lymphocytic leukemia, acute myeloid leukemia, or chronic myeloid leukemia.
- Exposure to certain chemicals
Being exposed to certain chemicals can also increase the risk of AML, ALL, and CLL. One of the main chemicals that are associated with leukemia is benzene, which is commonly found in gasoline, plastics, rubbers, dyes, pesticides, and cigarette smokes.
- Having chemotherapy for other cancers
Cancer patients who are treated with certain chemotherapy drugs are more likely to develop ALL or AML later on.
- Having certain blood disorders
People who have certain blood disorders, such as myelodysplastic syndrome (MDS) and idiopathic myelofibrosis, have an increased risk of developing acute myeloid leukemia.
The symptoms of leukemia vary depending on whether you have an acute or chronic type of leukemia.
People with acute lymphocytic leukemia (ALL) and acute myeloid leukemia (AML) will experience symptoms that are similar to the flu. They come on suddenly within days or weeks.
However, unlike flu symptoms, which generally subside as you get better, leukemia symptoms generally last longer than two weeks, and may include bone and joint pain, sudden weight loss, and easy bleeding or bruising.
In chronic leukemia, the cancer cells grow slowly. Therefore, people with chronic leukemia often experience only a few symptoms or none at all. The disease is usually found during a routine blood test. Possible symptoms of chronic leukemia include:
- Feeling very tired
- Frequent infections
- Night sweats
- Abdominal pain
- Painless lumps in the neck, underarm, or groin
The symptoms of leukemia are often vague and not specific to this disease. See your doctor if you have any complaints that are unusual, severe, or don’t go away because only a medical professional can help you determine if your symptoms are caused by leukemia.
If your doctor suspects you may have leukemia, they will ask you about any symptoms you have and may do a physical examination. Based on this information, your doctor may refer you to a specialist to check for leukemia or other health problems. Tests to diagnose leukemia include:
You will have blood tests to check the type, size, number, and appearance of blood cells and to see if leukemic cells are present.
Bone marrow tests
Your doctor may recommend a procedure to take a small sample of bone marrow from your hip bone (pelvis) and the sample is sent to a laboratory to be checked for abnormal cells.
A lumbar puncture, also called spinal tap, may be required to determine if the leukemia has spread to the cerebrospinal fluid (CSF), which surrounds the spinal cord and brain. This helps doctors choose the most appropriate treatment.
During a lumbar puncture, a needle is used to take a sample of the CSF to look for leukemia cells. Doctors may give an anesthetic to numb the lower back before the procedure.
There are many treatment options available for leukemia and the choice of treatments will depend on the type of leukemia you have, your age, your overall health, and whether leukemia cells have spread to other parts of your body.
If you have an acute leukemia you will usually need to start treatment as soon as possible. You will have some treatment as an inpatient in hospital. But if you have a chronic leukemia you may not need to start treatment straight away. You can usually have treatment as an outpatient.
Common treatment options for leukemia include:
Chemotherapy is the major form of treatment for leukemia. This drug treatment uses drugs to kill leukemia cells.
Depending on the type of leukemia you have, patients may receive a single drug or a combination of two or more drugs to achieve the optimal therapeutic outcome.
These drugs may be given by mouth (orally) or injection into a vein (intravenously).
This treatment uses X-rays or other high-energy beams to destroy leukemia cells and stop their growth.
During radiation therapy, you lie on a table while a large machine moves around you, directing the radiation to precise points on your body.
You may receive radiation at one specific area of your body where there is a collection of leukemia cells, or you may receive radiation over your whole body.
Immunotherapy, also known as biological therapy, is a treatment that uses certain drugs to enhance the body’s natural defenses against the disease.
One type of immunotherapy currently being used is called monoclonal antibody therapy. It uses monoclonal antibodies (mAb) that binds to the leukemia cells, helping the immune system to destroy them.
Depending on your particular situation, you may get the treatment in a clinic, or in the hospital. Your oncologist may also administer other drugs at the same time to prevent side effects.
Leukemia targeted therapy use drugs to block the growth of leukemia cells. For example, a targeted therapy drug called Imatinib (Gleevec) may block the action of an abnormal protein that stimulates the growth of leukemia cells.
Targeted therapy drugs may be used in combination with other leukemia treatments, such as chemotherapy. Unlike standard chemotherapy, which affects all cells in the body, targeted therapy directly attacks leukemia cells, helping to reduce damage to healthy cells and reduce side effects.
Stem cell transplantation
Stem cell transplantation or bone marrow transplantation is a procedure to replace the unhealthy blood-forming cells (stem cells) with healthy ones.
The healthy stem cells are collected either from the patient or a donor. If the cells are come from a donor, then careful testing must first be performed on the cells to find a good tissue match.
Before a stem cell transplant, you will receive high doses of chemotherapy or radiation therapy to destroy your damaged bone marrow. Then you receive an infusion of blood-forming stem cells that help to rebuild your bone marrow.
After a stem cell transplant, you may stay in hospital for several weeks or months. You will be at risk for bleeding and infection due to large doses of chemotherapy or radiation therapy you received. In time, the transplanted stem cells will begin to produce healthy blood cells.