Leukemia: Risk Factors, Symptoms & Treatment

Medically Reviewed by Kelsey Powell, MS, Medical Sciences

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Leukemia is a form of cancer that affects blood-forming tissues and/or cells — primarily those of the lymphatic system and bone marrow. This cancer most often impacts white blood cells, but it can also develop in other types of blood cells as well. Moreover, it's different from most other cancers because the cancerous cells circulate throughout the bloodstream, as opposed to forming a mass or tumor.

Leukemia occurs when the bone marrow produces an excessive amount of abnormal white blood cells (leukemia cells) that do not function properly. These continually replicating leukemia cells start to crowd normal white and red blood cells along with platelets and prevent these normal cells from carrying out their regular functions, thus wreaking havoc on the body.

Are There Different Types of Leukemia? 

Leukemia is actually a blanket term that can refer to a spectrum of related cancers. The different types of leukemia can be broken down into two different groups, which are determined by how fast the disease develops:

  • Chronic Leukemia: This type of leukemia progresses slowly and is more common in adults. Symptoms may not be present in early stages because the leukemia cells are still able to at least partially function in the capacity of normal white blood cells. However, as the amount of leukemia cells slowly begins to increase, the signs and symptoms of leukemia begin to appear.
  • Acute Leukemia: This type of leukemia progresses quickly and is the most common cancer in children. The leukemia cells rapidly divide and cannot function like normal white blood cells. Because the leukemia cells crowd out normal, functioning cells at such a fast pace, symptoms can grow progressively worse, very quickly.

Different types of leukemia are also classified by the particular type of cell that is affected. The four most common types are:

  • Chronic lymphocytic leukemia (CLL): This cancer originates from lymphoid cells, which normally develop into white blood cells. It typically affects older adults (over 65 years of age) and accounts for approximately one-third of all leukemia cases.
  • Chronic myeloid leukemia (CML): This leukemia originates from myeloid cells, which normally develop into red or white blood cells or platelets. It also mainly affects older adults but only accounts for approximately 10% of all leukemia cases.
  • Acute lymphocytic leukemia (ALL): This cancer originates from lymphoid cells, but it spreads quickly. It is the most common leukemia in children, adolescents, and young adults (under 39 years of age).
  • Acute myeloid leukemia (AML): This leukemia originates from myeloid cells and spreads quickly. It occurs in children and adults but is most common in older adults.

Although they are rarer, other types of leukemia include hairy cell leukemia, myelodysplastic syndromes, and myeloproliferative disorders

 Symptoms Associated With Leukemia 

Chronic leukemia may be asymptomatic for a long period of time because the disease progresses slowly, meaning it's commonly diagnosed during routine check-ups or while checking for other health issues. Usually, the first sign of chronic leukemia is an enlarged lymph node. Although symptoms for leukemia vary based the type of leukemia, common symptoms include:

  • Fever
  • Fatigue
  • Paleness
  • Frequent or recurrent infections
  • Unexplained weight loss
  • Swollen lymph nodes
  • Enlarged liver or spleen
  • Easy bleeding and/or bruising
  • Appearance of tiny red spots on the skin (petechiae)
  • Night sweats
  • Bone or joint pain
  • Shortness of breath
  • Pain or pressure on the left side under the ribs

Causes & Risk Factors

Generally, leukemia results from genetic mutations that cause abnormal and accelerated cell division, but the exact causes of these mutations remains unclear. Still, leukemia abnormalities appear to stem from both genetic and environmental factors, including: 

  • Smoking
  • Chemical exposure (e.g. benzene, formaldehyde)
  • Genetic disorders (e.g. Down's Syndrome, Klinefelter Syndrome, neurofibromatosis, Schwachman-Diamond Syndrome)
  • Previous cancer treatments (e.g. radiation, chemotherapy)
  • Family history of leukemia

Note: Anyone can develop leukemia at any age whether these risk factors are present or not.