Risks for acute leukemia

Some things can affect your risk, or chance, of developing cancer. Certain behaviours, substances or conditions can increase or decrease the risk. Most cancers are the result of many risks. But sometimes cancer develops in people who don't have any risks.

Acute leukemia includes 2 types of leukemia – acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). Some risks may be different for ALL and AML, and some may be the same.

The risk of developing AML increases with age. It usually occurs in people who are 65 and older. ALL is more common in children and in adults over the age of 50.

Men develop acute leukemia slightly more often than women. We need more research and can't say at this time what the risk is for transgender, non-binary and gender-diverse people.

The following can increase your risk for acute leukemia.

There is convincing evidence that coming into contact with high levels of radiation, such as radiation from nuclear reactor accidents, is a risk for acute leukemia. Most leukemias that develop after exposure to radiation are AML rather than ALL.

There is convincing evidence that radiation therapy given in the past to treat cancer or other health conditions increases the risk of acute leukemia. Having had both radiation therapy and chemotherapy to treat cancer increases the risk more than having had radiation therapy alone.

This risk is higher for AML than for ALL.

There is convincing evidence that certain chemotherapy drugs or drug combinations increase the risk of developing AML, but the risk is very low. The benefits of having chemotherapy to treat cancer far outweigh this risk.

The following types of chemotherapy drugs and combinations are known to increase the risk of AML:

• alkylating agents (especially thiotepa, procarbazine, dacarbazine, temozolomide)

• topoisomerase 2 inhibitors (epirubicin, mitoxantrone, etoposide)
• platinum drugs (cisplatin, carboplatin)
• carmustine (also called BCNU)
• lomustine (also called CCNU)
• semustine (also called methyl-CCNU)
• MOPP – a drug combination with mechlorethamine hydrochloride, vincristine, procarbazine and prednisone

Having both chemotherapy and radiation therapy to treat cancer increases the risk of developing AML even more than having just chemotherapy alone.

People with a history of the following blood disorders have a higher risk of developing AML:

• myelodysplastic neoplasms (formerly called myelodysplastic syndromes)

• myeloproliferative disorders including polycythemia vera, essential thrombocythemia and myelofibrosis
• chronic myeloid leukemia (CML)

These blood disorders can change and become AML (called a transformation). But not everyone with these blood disorders will develop AML.

A genetic condition is a disease caused by a change (mutation) in one or more genes. Having certain genetic conditions increases the risk of developing acute leukemia, especially in childhood.

The following inherited genetic conditions increase the risk of both ALL and AML.

Down syndrome is a condition caused by an extra (third) copy of chromosome 21. It causes different birth defects, intellectual disability, a characteristic facial appearance and poor muscle tone in infancy.

Bloom syndrome is a condition caused by mutations in a certain chromosome. Signs include shorter than average height, a high-pitched voice and a characteristic facial appearance.

Ataxia-telangiectasia (AT) is a rare disease that affects the nervous system, immune system and other body systems. Signs and symptoms include loss of balance, poor coordination, frequent infections, red eyes (due to widening of blood vessels) and abnormal eye movements.

Li-Fraumeni syndrome is an condition that is associated with an increased risk of developing many different cancers in both adults and children.

Neurofibromatosis type 1 is a condition that affects the nervous system. It affects the development and growth of nerve cells, causes tumours to grow on nerves and may cause other abnormalities in muscles, bone and skin.

The following genetic conditions increase the risk of AML, but it's not clear if they increase the risk of ALL.

Klinefelter syndrome is a sex chromosome disorder in which someone assigned male at birth has at least one extra X chromosome. The signs of Kleinfelter syndrome are different depending on the person's age. Signs include small testicles, weak muscles, enlarged breasts, taller than average height and less facial and body hair than most men.

Fanconi anemia affects the bone marrow so it cannot make red blood cells, white blood cells or platelets.

There is convincing evidence that benzene causes AML. People are exposed to benzene by breathing air that has benzene in it. Benzene can be found in:

• tobacco smoke, including second-hand smoke

• gasoline fumes and vehicle exhaust
• glues, adhesives, cleaning products and paint strippers
• environmental sources such as smoke from forest fires or gas from volcanoes

People who work in industries that use benzene, such as chemical and pharmaceutical companies, may be exposed to higher levels of benzene.

There is convincing evidence that smoking increases the risk of AML. This may be because there is benzene and formaldehyde in tobacco.

Formaldehyde is a colourless gas. People are exposed to formaldehyde by breathing air that has formaldehyde in it. Formaldehyde can be found in:

• funeral homes (formaldehyde is used in embalming) and laboratories with preserved specimens

• the production and use of fertilizer, paper, plywood, plastics, resins and foam insulation
• household cleaners, medicines and other products as a preservative
• tobacco smoke, including second-hand smoke

People who work in industries that use formaldehyde, such as agriculture, construction and funeral services, may be exposed to higher levels of formaldehyde.

There is convincing evidence that having a family history of AML increases your risk of developing AML. The risk is higher if one of your first-degree relatives (your parent, sibling or child) has been diagnosed.

Children who have an identical twin who develops ALL or AML in the first year of life have a greater risk of developing acute leukemia.

Infection with the human T-cell leukemia/lymphoma virus, type 1 (HTLV-1) increases the risk of developing T-cell ALL, a rare type of ALL. In many cases, people carrying the virus do not get symptoms or develop health problems from it. Only a few people who have HTLV-1 will develop leukemia.

HTLV-1 is not common in Canada. It is more common in Japan and the Caribbean.

There are some things that may increase your risk for acute leukemia. More research is need to know for sure that they are risks. The following have been linked with ALL, AML or both:

• obesity
• contact with pesticides over a long period of time
• a weakened immune system because of autoimmune disease or having an organ transplant (AML)
• exposure to diesel fumes

To make the decisions that are right for you, ask your doctor questions about risks. Learn how cancer can be prevented and what you can do to reduce your risk.