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A risk factor is something (such as a behaviour, substance or condition) that increases the risk of developing cancer. Most cancers are the result of many risk factors, but sometimes acute lymphocytic leukemia (ALL) develops in people who don’t have any of the risk factors described below.
More men than women develop ALL.
Risk factors are generally listed in order from most to least important. But in most cases, it is impossible to rank them with absolute certainty.
There is convincing evidence that the following factors increase your risk for ALL.
Genetic syndromes are groups of symptoms caused by a change, or mutation, in one or more genes. They are passed from parents to children. Having certain genetic syndromes can increase the risk of developing ALL, especially childhood ALL. The following genetic syndromes increase the risk for ALL. Other genetic syndromes may also increase the risk of ALL.
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. People with Down syndrome have a higher risk of developing several medical conditions, including childhood leukemia.
Bloom syndrome is a condition caused by a large number of abnormal chromosomes. People with Bloom syndrome are usually smaller than average, have a high-pitched voice and a characteristic facial appearance. People with Bloom syndrome have a higher risk of developing different types of cancer, including ALL.
Fanconi anemia is a condition that mainly affects the bone marrow so that it doesn’t make enough healthy red blood cells, white blood cells and platelets. People with Fanconi anemia have a higher risk of developing leukemia.
Ataxia-telangiectasia (AT) is a rare condition that affects the nervous system, immune system and other body systems. People with AT have problems with walking, balance and coordination. They often have a weakened immune system and a higher risk of developing cancer, particularly lymphoma and leukemia.
Li-Fraumeni syndrome is a rare condition that greatly increases the risk of developing several types of cancer, including breast cancer, osteosarcoma, soft tissue sarcomas, brain cancer and leukemia.
Neurofibromatosis type 1 (von Recklinghausen disease) is a condition in which tumours that start in nerve tissue form in the skin, just under the skin and in cranial and spinal cord nerves. People with neurofibromatosis type 1 have a higher risk of developing certain cancers, including leukemia.
Klinefelter syndrome is a condition caused by an extra copy of the X chromosome in males. It affects male sexual development. Klinefelter syndrome also increases the risk of leukemia.
Exposure to high doses of radiation is a risk factor for ALL. Survivors of the atomic bomb explosions in Japan during the Second World War have a higher risk of developing ALL. People exposed to radiation from nuclear reactor accidents also have a higher risk of developing ALL. But most leukemias that develop after exposure to radiation are acute myelogenous leukemia (AML) rather than ALL.
Infection with the human T-cell leukemia/lymphoma virus, type 1 (HTLV-1) increases the risk of developing a rare type of T-cell ALL. HTLV-1 is not common in Canada. It is more common in Japan and the Caribbean.
The following factors have been linked with ALL, but there is not enough evidence to show they are known risk factors. Further study is needed to clarify the role of these factors for ALL.
Radiation therapy given to treat cancer or other health conditions increases the risk of secondary leukemia. The leukemia that develops is usually acute myelogenous leukemia (AML). But some studies have shown that radiation may also increase the risk of ALL.
Certain types of chemotherapy given to treat children or adults with cancer can increase the risk of secondary leukemia. The leukemia that develops is usually AML. But some studies have shown that there may be a small increase in risk of ALL.
Exposure to benzene increases the risk of leukemia. The leukemia that develops is usually AML. But some studies have shown an association with ALL.
People who are overweight or obese have a higher risk of developing certain types of cancer. Some studies have shown that people who are overweight or obese have a higher risk of developing leukemia than people with a normal body weight.
It isn’t known whether or not the following factors are linked with ALL. It may be that researchers can’t show a definite link or that studies have had different results. Further study is needed to see if the following are risk factors for ALL:
To make the decisions that are right for you, ask your healthcare team questions about risks.