Risk factors for ALL

The exact pathogenetic events responsible for the development of ALL are unknown.

But the following factors have been associated with an increased risk of developing ALL:

• environmental factors
  • prenatal exposure to X-rays
    • 1.5 fold increase in risk was observed in diagnostic X-ray exposure in uteri
    • nowadays this is not significant since there are fewer x rays carried out prenatally and even when carried out there is increased shielding, and lower radiation levels
• postnatal exposure to high doses of radiation
  • therapeutic radiation was previously used for conditions such as tinea capitis and thymus enlargement (1,2)
• genetic conditions
  • a higher incidence of ALL is observed amongst monozygotic and dizygotic twins of ALL patients (3)
  • Down syndrome
    • around one half to two thirds of cases of acute leukaemia in children with Down syndrome are ALL
  • increased occurrence of ALL is also seen in other genetic conditions such as neurofibromatosis, Shwachman syndrome, Bloom syndrome and ataxia telangiectasia (2)
• infection
  • three hypothesis regarding infectious aetiology are: exposure in utero or around the time of birth, delayed exposure beyond the first year of life to common infections and unusual population mixingo breast feeding and day care attendance in the first year of life seems to have a protective effect (4)

There have been conflicting or isolated reports on the following factors which are thought to increase the risk of the disease:

• socioeconomic factors - affluent societies, and in urban areas (5)
• parental occupation
• maternal reproductive history
• parental tobacco or alcohol use
• maternal diet and prenatal vitamin use
• exposure to pesticides or solvents
• exposure to the highest levels of residential, power-frequency magnetic fields (6)

Reference:

• 1. Bassan R et al. Adult acute lymphoblastic leukaemia. Crit Rev Oncol Hematol. 2004;50(3):223-61.
• 2. National Cancer Institute at the National Institutes of Health. General Information About Adult Acute Lymphoblastic Lekemia (ALL)
• 3. Jabbour EJ et al. Adult acute myeloid leukemia. Mayo Clin Proc. 2006;81(2):247-60.
• 4. McNally RJ, Eden TO. An infectious aetiology for childhood acute leukaemia: a review of the evidence. Br J Haematol. 2004;127(3):243-63.
• 5. Faderl S et al. Adult acute lymphoblastic leukemia: concepts and strategies. Cancer. 2010;116(5):1165-76.
• 6. Pui CH, Robison LL, Look AT. Acute lymphoblastic leukaemia. Lancet. 2008;371(9617):1030-43.