Types of Cancer: Leukemia
Updated: Jun 22, 2022
By: Sonya Sar
If you’ve heard of leukemia, you probably know it as a children’s disease, or a form of cancer only affecting children. However, many people don’t know that most cases of leukemia are actually found in older adults; out of the four types of leukemia, about 2 really affect children, while all of them occur in adults.
So what really is leukemia? Leukemia is a term referring to all cancers found in the blood-forming tissue, and it affects the lymphatic system, which is a part of the immune system as well as complementary to the circulatory system. This type of cancer involves white blood cells (WBCs), which are cells that protect us from infection. Leukemia usually starts off in bone marrow where white blood cells are formed before moving into the blood and spreading to other parts of the body.
Leukemia is caused by mutations in the white blood cells’ DNA, which usually sets the growth rate and determines necessary cell death of WBCs (that’s right, cell death is sometimes necessary for all cells in the body, and it’s called apoptosis if you’re interested in learning more about it). But, when certain mutations occur, they prevent proper measures from being set, and so the cells start to grow and divide excessively. This will cause an imbalance in the production of unhealthy and healthy white and red blood cells, and eventually the amount of cancerous white and red blood cells will overtake the amount of healthy white and red blood cells. This imbalance can stop WBC from fighting infections, and this causes frequent or severe infections in leukemia patients. This imbalance also leads to other common symptoms such as fevers, persistent fatigue, easy bleeding and bruising, nosebleeds, weakness, chills, and swollen lymph nodes in more serious cases. In patients with leukemia, it is found that they can have very high white blood cell counts, but it’s important to remember that having a high white blood cell count doesn’t automatically mean that you have cancer. A plethora of reasons such as infection, immune system disorders like lupus, and excessive emotional or physical stress caused by fevers or surgery can also lead to a high WBC count. There are certain risk factors involved with developing leukemia such as genetic disorders, exposure to certain chemicals, smoking, family history, and certain types of chemotherapy or radiation therapy.
Leukemia can be classified in two different ways: how it progresses and the type of white blood cell it affects. The two types that are based off of progression are acute leukemia and chronic leukemia. Acute leukemia is found when there are abnormal white blood cells that can’t carry out normal functions, and they multiply rapidly and worsen quickly. Chronic leukemia is found when white blood cells mutate at a much slower rate than those found in acute leukemia, so it takes much longer for symptoms to appear. The two types that are based on the type of white blood cell are lymphocytic leukemia and myelogenous leukemia. Lymphocytic leukemia affects the white blood cells in the immune system called lymphocytes. Myelogenous leukemia, also known as myeloid leukemia, affects the cells that give rise to red and white blood cells, called myeloid cells. This means that patients are diagnosed with one of the following four types of leukemia: chronic lymphocytic leukemia, chronic myeloid leukemia, acute lymphocytic leukemia (also known as acute lymphoblastic leukemia), and acute myeloid leukemia (AML). This classification might seem like a lot of complicated terminology, but it’s super important to cancer doctors (called oncologists) since each type of leukemia requires a different treatment plan.
Unlike other types of cancer, leukemia doesn’t form tumors, so doctors can’t utilize imaging tests such as CT scans or MRIs to identify and diagnose leukemia. Instead, doctors use three different exams to test whether a patient has leukemia or not. The first one is a physical exam where they check for physical signs of leukemia such as swelling of lymph nodes, pale skin, or enlargement of liver or spleen. The second one is a blood test to check whether the patient has abnormal levels of red and white blood cells. However, it’s important to remember that leukemia can’t always be detected through blood tests even though it is a type of cancer involving blood cells. White blood cells are also found in bone marrow, and that is what the third test looks for. A sample of bone marrow is removed to look for abnormalities in white blood cells.
Once diagnosed, there are multiple pathways for treatment that can be taken. Chemotherapy, which is when a specific drug or combination of drugs are used to kill leukemia cells, is one method. Other methods are targeted therapy, which focuses on blocking specific abnormalities within cancer cells to stop the growth and division of these cells, and radiation therapy, where high-energy beams are used to damage leukemia cells and stop their growth. There were also new medications that were approved by the FDA (Food and Drug Administration). Enasidenib is a drug that targets mutated forms of IDH2 protein, which has been proven to lead to the production of a specific inhibitor that promotes the formation of leukemia. CPX-351 is a two-drug chemotherapy combination encased in small fatlike particles, and it’s used in patients with one of the two high-risk forms of AML. According to the American Cancer Society, about 2 out of 3 patients with acute myeloid leukemia who undergo standard chemotherapy will go into remission; this means that the doctors have successfully reduced the WBC count to normal levels and there are no more signs or symptoms of the disease. Because of the success rate of this treatment, chemotherapy is typically the standard procedure used to treat AML.
Leukemia, as discussed previously, is a type of cancer caused by mutations in white blood cells, which leads to excessive growth and division; since it doesn’t form tumors like other cancers, it can’t be detected through imaging tests. Doctors will usually check for physical signs of leukemia or take a sample of blood or bone marrow to check for abnormalities in the WBC count. Patients might get frequent or severe infections, fever or chills, and persistent fatigue as well as other symptoms if they have leukemia. Keep in mind though that if someone has leukemia, then they will experience multiple symptoms.
An imbalance in your WBC can make you susceptible to more frequent or severe infections, so even though it can be difficult to prevent leukemia, it’s important to regularly check your blood cells count especially if you’re above the age of 65. As always, if you have any questions about some signs or symptoms that you feel might be connected to leukemia, you can take a look at the links below, but remember that your doctor is your best resource!
American Cancer Society. (2018, August 21). Treatment Response Rates for Acute Myeloid Leukemia
American Cancer Society. (2018, October 17). What is Acute Lymphocytic Leukemia?
Cleveland Clinic Staff. (2022, May 18). Leukemia. https://my.clevelandclinic.org/health/diseases/
Cleveland Clinic Staff. (2022, January 19). Leukocytosis (High White Blood Cell Count).
Issa, G. C., & DiNardo, C. D. (2021). Acute myeloid leukemia with IDH1 and IDH2 mutations: 2021
treatment algorithm. Blood cancer journal, 11(6), 107. https://doi.org/10.1038/s
Mayo Clinic Staff. (2021, January 13). Leukemia. https://www.mayoclinic.org/diseases-conditions/
NCI Staff. (2017, August 28). Two New Therapies Approved for Acute Myeloid Leukemia.
Cleveland Clinic Staff. (2019) Normal blood contains red blood cells, white blood cells and platelets.
Leukemia cells outnumber normal cells in leukemia. Cleveland Clinic.