There is no evidence of chronic lymphocytic leukemia (CLL) transmission as a result of a blood transfusion from a donor who later developed CLL, according to a study of the Scandinavian Donations and Transfusions (SCANDAT2) database and Swedish and Danish cancer registries.1

Concern of the potential transmission of monoclonal B-cell lymphocytosis (MBL) through blood products has been raised due to several studies that determined MBL to be somewhat common in the general population,2 and present in about 7.1% of more than 2000 blood donors in a US-based study.3

In addition, some studies have found blood transfusion recipients to have an increased risk of CLL and/or small lymphocytic leukemia (SLL). However, this finding is not consistent, as other studies have found no risk or an inverse risk for the development of CLL or SLL following blood transfusion.4-6

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“We determined if CLL among recipients clustered to individual donors, whether these developed CLL after the donation and therefore at increased risk of MBL at time of donation, or not,” wrote Henrik Hjalgrim, MD, PhD, of the Department of Epidemiology Research at Statens Serum Institut in Copenhagen Denmark, and colleagues.1

The study analyzed data from donors and recipients of more than 20 million blood products from the SCANDAT2 database between 1968 and 2010. The SCANDAT2 database contains data from patients who donated or received blood in Sweden and Denmark.

The blood products assessed for potential transmission of MBL or CLL included whole blood, red blood cell products, and platelet products. MBL donor status was not known, but was inferred by postdonation CLL diagnosis. For CLL diagnoses, data were collected from Danish and Swedish cancer registries using national classification codes.

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The investigators identified 2 groups of donors. The first group was donors who were diagnosed with CLL after their earliest registered donation. The second group comprised of donors without CLL who were matched to the first group based on age, sex, county, number of donations, and ABO blood group.