Vitamin K and leukaemia: one study finds no link, but others don't completely exclude a risk

Vitamin K and leukaemia: one study finds no link, but others don't completely exclude a risk

In the early 1990s two reports by Golding et al suggested thatthe risk of childhood cancer, particularly leukaemia, was doubledin children who had received prophylactic intramuscular vitaminK at birth. None of the subsequent research found any significantassociation, but these studies used different methods and werehampered by lack of power. This week's issue includes four morestudies: all provide further evidence against an effect of thevitamin K of the size suggested by Golding et al.

The first, by McKinney et al, failed to show any significantassociation between cancer and vitamin K (p 173). In a populationbased case-control study in Scotland designed to identify riskfactors for childhood cancer they investigated vitamin K byusing information in hospital records and found no significantlyraised risks for leukaemia or any other type of cancer. Accountingfor other factors that might explain an association, such astype of delivery or deprivation, did not alter their findings.

Two studies (case-control and ecological) by Passmore et al(p 178, 184) and another case-control study by Parker et al(p 189) do not, however, exclude a possible association withleukaemia. Passmore et al consider that this might be explainedby the association they found between type of delivery and riskof leukaemia. Parker et al found no association with non-leukaemiamalignant disease but were unable to rule out an associationwith acute lymphoblastic leukaemia, especially for that diagnosedin children aged 1-6 years. Passmore et al and Parker et alsuggest that their results support a policy of giving intramuscularvitamin K only to babies at high risk of vitamin K deficiencybleeding, with oral vitamin K being given to the others.