NEW YORK (Reuters Health) - People who receive a blood transfusion from a donor with undiagnosed cancer do not appear to be at increased risk of developing the malignancy themselves, new research indicates.

The findings, reported in The Lancet, were from an analysis of data entered in Swedish and Danish blood bank registers from 1968 to 2002. Blood donors diagnosed with cancer within 5 years of donation were considered to have had a subclinical malignancy at the time of donation.

A total of 354,094 transfusion recipients were included in the analysis. Of these, 12,012 were thought to have received blood from a donor with undiagnosed cancer, lead investigator Dr. Gustaf Edgren, from the Karolinska Institute in Stockholm, and colleagues report.

There was no evidence that recipients of blood from donors with undiagnosed cancer were any more or less likely to develop cancer than recipients given blood from non-cancer donors.

"While randomized trials of different transfusion thresholds provide necessary information about acute outcomes, they do not offer much hope of defining the clinical consequences of transfusion years to decades later, particularly for relatively rare outcomes," Dr. Garth H. Utter, from the University of California, Davis, at Sacramento, comments in a related editorial.

"With their thoughtful analysis of a large and relatively complete dataset, Edgren and colleagues have taken an important stride forward in evaluating one of these potential long-term risks of blood transfusion."