A risk factor is any factor that is associated with increasing someone’s chances of developing a certain condition, such as cancer. Some risk factors are modifiable, such as lifestyle or environmental risk factors, and others cannot be modified, such as inherited factors or whether someone in the family has had cancer.

Having 1 or more risk factors does not mean that you will develop cancer. Many people have at least 1 risk factor but will never develop cancer, while others with cancer may have had no known risk factors. Even if a person with cancer has a risk factor, it is usually hard to know how much that risk factor contributed to the development of their disease.

Factors that are associated with a higher risk of developing leukaemia include the following:

• ALL
  • exposure to high levels of radiation
  • exposure to certain chemicals, including the solvent benzene, and chemotherapy medicines
  • infection with Epstein–Barr virus or human T-cell lymphoma/leukaemia virus 1 (HTLV-1)
  • certain genetic syndromes, including Down syndrome, Klinefelter syndrome, Fanconi anaemia, Bloom syndrome, ataxia-telangiectasia and neurofibromatosis,
  • sex of the patient – ALL is more common in males than in females
  • having an identical twin with ALL
• AML
  • smoking
  • exposure to high levels of radiation
  • exposure to certain chemicals, including the solvent benzene, and chemotherapy medicines
  • certain blood disorders, including chronic myeloproliferative disorders
  • certain genetic syndromes, including Down syndrome, trisomy 8, Fanconi anaemia, Bloom syndrome, ataxia-telangiectasia, Diamond–Blackfan anaemia, Shwachman–Diamond syndrome, Li–Fraumeni syndrome, neurofibromatosis type 1 and severe congenital neutropaenia
  • having an identical twin or another close relative with AML
  • age – the risk of AML increases with age
  • sex of the patient – AML is more common in males than in females
  • having had treatment for ALL in childhood
• CLL
  • exposure to certain chemicals, possibly including the herbicide Agent Orange, and some pesticides
  • having a close relative with CLL
  • age – CLL is more common after middle age
  • sex of the patient – CLL is slightly more common in males than in females
  • racial background – CLL is less common in people with an Asian background than in non-Asians; it is also more common in Russian or eastern European Jews
• CML
  • exposure to high levels of radiation
  • age – the risk of CML increases with age
  • sex of the patient – CML is slightly more common in males than in females.

Find out more about:

• Lifestyle and risk reduction
• Position Statement on Lifestyle risk factors and the primary prevention of cancer