Leukemia risk factors: what raises the risk, by type

What leukemia is

Leukemia is a term for cancers of the blood cells. It starts in blood-forming tissue such as the bone marrow, which makes large numbers of abnormal cells, most often white blood cells. These cells crowd out healthy blood cells (MedlinePlus). Leukemia happens when the genetic material (DNA) in bone marrow cells changes, and the cause of those changes is unknown (MedlinePlus).

MedlinePlus names 4 main types (MedlinePlus):

• Acute lymphocytic leukemia (ALL): the most common type of cancer in children; it can also affect adults.
• Acute myeloid leukemia (AML): more common in older adults, but it can also affect children.
• Chronic lymphocytic leukemia (CLL): one of the most common types of leukemia in adults, often during or after middle age.
• Chronic myeloid leukemia (CML): usually in adults during or after middle age.

Acute leukemia grows fast and usually gets worse quickly without treatment. Chronic leukemia grows slowly (MedlinePlus).

The risk factor every type shares: age

Each type has its own risk factors, but overall the risk of leukemia goes up as you age. It is most common over age 60 (MedlinePlus).

A risk factor is anything that raises the chance of getting a disease. Having one does not mean you will get leukemia, and some people with no known risk factor do get it (NCI PDQ) (NCI PDQ).

Risk factors for AML in adults

NCI lists these possible risk factors for AML (NCI PDQ):

• being male
• older age
• smoking
• past treatment with chemotherapy or radiation therapy
• exposure to radiation in the environment (such as nuclear radiation) or to the chemical benzene
• a personal history of a blood disorder such as myelodysplastic syndrome
• certain syndromes or inherited disorders

NCI notes that smoking is one risk factor that can be changed, while genes, age and health history cannot (NCI PDQ). If you smoke, the quit smoking check is a place to start.

CLL and CML

NCI's patient summaries for the 2 chronic types do not give a list of risk factors. They describe who gets them: CLL often occurs during or after middle age and rarely in children (NCI PDQ), and CML usually occurs during or after middle age and rarely in children (NCI PDQ).

Most people with CML have a gene change called the Philadelphia chromosome. NCI says this change is not passed from parent to child (NCI PDQ).

Risk factors in children

Children have their own lists. For childhood ALL, NCI names these possible genetic risk factors (NCI PDQ):

• Down syndrome
• neurofibromatosis type 1
• Bloom syndrome
• Fanconi anemia
• ataxia-telangiectasia
• Li-Fraumeni syndrome (TP53 gene)
• constitutional mismatch repair deficiency
• certain other changes in chromosomes or genes

Other possible risk factors for childhood ALL are exposure to x-rays before birth, exposure to radiation, and past treatment with chemotherapy (NCI PDQ). Childhood ALL occurs most often in children aged 1 to 4 years (NCI PDQ).

For childhood AML and related myeloid diseases, NCI lists (NCI PDQ):

• having a brother or sister, especially a twin, with leukemia
• a personal history of bone marrow failure or myelodysplastic syndrome (MDS)
• past treatment with chemotherapy or radiation therapy
• exposure to ionizing radiation or chemicals such as benzene
• certain syndromes or inherited disorders, such as Down syndrome, aplastic anemia, Fanconi anemia, neurofibromatosis type 1, Noonan syndrome, Shwachman-Diamond syndrome, Diamond-Blackfan anemia, dyskeratosis congenita and Li-Fraumeni syndrome

It is not always clear from family history whether a child with ALL has an inherited condition. NCI says genetic counseling can help a family judge whether genetic testing makes sense (NCI PDQ).

Symptoms to check with a doctor

MedlinePlus lists these possible symptoms (MedlinePlus):

• feeling tired
• fever or night sweats
• easy bruising or bleeding
• weight loss or loss of appetite
• petechiae, tiny red dots under the skin caused by bleeding

Symptoms differ by type. Chronic leukemia may not cause symptoms at first (MedlinePlus), and CLL may be found during a routine blood test (NCI PDQ). Early AML symptoms can look like the flu or other common illnesses (NCI PDQ). In children, NCI adds bone or joint pain, pale skin, shortness of breath and painless swollen lymph nodes (NCI PDQ). These symptoms can also have other causes, so see a doctor rather than guess.

How leukemia is found

A provider may use a physical exam, your medical history, blood tests such as a complete blood count (CBC), bone marrow tests and genetic tests that look for gene and chromosome changes (MedlinePlus). As leukemia cells build up, there is less room for healthy red blood cells and platelets, which may lead to anemia, easy bleeding and infection (NCI PDQ).

Our cancer screening hub covers the cancers that have screening checks for people without symptoms.

Common questions

Is leukemia the same as blood cancer?

MedlinePlus describes leukemia as a term for cancers of the blood cells (MedlinePlus). This page covers leukemia only; other cancers that start in blood-forming cells have their own risk factor lists, such as lymphoma risk factors and multiple myeloma risk factors.

At what age is leukemia most common?

Overall, over age 60 (MedlinePlus). Childhood ALL is the exception: it is the most common cancer in children and occurs most often between ages 1 and 4 (NCI PDQ).

Is leukemia inherited?

Some inherited syndromes, such as Down syndrome, Fanconi anemia and Li-Fraumeni syndrome, raise the risk in children (NCI PDQ) (NCI PDQ), and a brother or sister, especially a twin, with leukemia raises the risk of childhood AML (NCI PDQ).