Affecting nearly 450,000 people in the U.S. alone, leukemia is one of the most common cancers among people over the age of 55 and also among people under the age of 20. For some weird reason, leukemia tends to affect men more than women and is more common among caucasians than african-american individuals.

Simply put, leukemia refers to the cancer of the white blood cells. It occurs when gene mutations occur in normal white blood cells, resulting in the development of abnormal WBCs in the bone marrow which quickly spread, destroying normal blood cells and thus altering the normal functioning of the body. Even though the exact cause of this is unknown, various studies and experiments have helped identify several risk factors. These include:

• A family history of leukemia
• Genetic disorders (i.e., down syndrome)
• Exposure to high levels of radiation (i.e., therapies like chemo)
• Lifestyle habits, such as smoking
• Exposure to chemicals (i.e., pesticides and benzene)
• Race, age, and gender

Leukemia is often classified depending on the location of the cancerous cells and also depending on how quickly it develops and spreads. In respect to that, here are the most common leukemia types:

1. Acute myeloid leukemia
Also referred to as acute myelogenous, this type of leukemia often affects the myeloid cells of the white blood group hence the name. Acute myeloid leukemia is the most rampant form of leukemia, and it tends to affect both children and adults but is more prevalent in adults. Even though it has a survival rate of five years, it progresses quite fast and requires urgent treatment.

2. Chronic myeloid leukemia
As the name implies, chronic myeloid leukemia also begins in the myeloid cells. Also known as chronic granulocytic, it is usually more common in adults at the age of 60 and above and is rare in children. It is different from other types of leukemia as it triggered by abnormal chromosomes. This type of cancer grows slowly and boasts a five-year survival rate of 66.9% which means it is possible to treat and prevent it from coming back if discovered early enough.

3. Acute lymphocytic leukemia
Commonly referred to as ALL, acute lymphocytic leukemia often affects the lymphocyte cells. In this case, the bone marrow often makes excess immature lymphocytes such that they end up outnumbering the normal white blood cells. This form of leukemia grows quite rapidly and quickly progresses to other organs and tissues such as the brain, the lymph nodes, the spleen and in men, the testes. Unfortunately, they continue spreading here as well. The good news is that it less common in adults and bad news is that it is more rampant among children, those under the age of five being at a higher risk of developing this leukemia. The bright side however is that acute lymphocytic leukemia is more treatable in children and they often stand a higher chance of getting better.

4. Chronic lymphocytic leukemia
Similar to ALL, CLL also originates in the lymphocyte cells. Unlike ALL, it is more prevalent in adults at the age of 70 and above and is rarely diagnosed in kids. It is a slow cancer and has a high survival rate of 83.2%. Nevertheless, there are several subtypes of CLL which tend to progress very quickly.

5. Hairy cell leukemia
This form of leukemia is incredibly rare and accounts for only 2% of all leukemia. HCL affects the lymphocyte cells and progresses very slowly. Good news is that the majority of its treatments are often successful. The name hairy cell leukemia is as a result of the hairy appearance of the cells under a microscope.