“The results, which have to be considered reliable, settle one of the few remaining questions surrounding the safety of blood transfusions,” says Professor Olof Nyrén of the Department of Medical Epidemiology and Biostatistics and the leader of the project.

The study was carried out in collaboration with researchers at Statens Serum Institut in Copenhagen. Digital information on 1.13 million blood donors and 1.31 million transfusion recipients in Sweden and Denmark was gathered, allowing the scientists to identify over 12,000 patients who had received blood from donors who were diagnosed with cancer within five years of the transfusion.

The recipients were followed for as long as 34 using record linkage with the Swedish and Danish cancer and cause-of-death registers and other such data. The control group consisted of 342,000 patients who could be said with certainty to have not received blood from donors with latent cancer. The cancer risk of the two groups were compared using statistical methods, taking into account sex, age, place of residence, blood group, number of transfusions and time since the first transfusion.

The team found that the patients in the two comparison groups had exactly the same cancer risk. No matter how the data was analysed, there was no evidence to suggest that patients who had received blood from donors with a yet undiagnosed tumour ran a greater risk of developing cancer themselves.

“Even though transfusion procedures are very safe, we are still constantly trying to identify any possibly overlooked risks,” says Professor Nyrén. “The Swedish-Danish database that was built for this project can come in very useful here too.”

“Risk of cancer after blood transfusion from donors with subclinical cancer: a retrospective cohort study”
Gustaf Edgren, Henrik Hjalgrim, Marie Reilly, Trung N Tran, Klaus Rostgaard, Agneta Shanwell, Kjell Titlestad, Johanna Adami, Agneta Wikman, Casper Jersild, Gloria Gridley, Louise Wideroff, Olof Nyrén and Mads Melbye
The Lancet, 18 May 2007

For further information, please contact:

Doctoral student Gustaf Edgren (principal author)
Tel: +46 (0)8-524 861 40 or +46 (0)708-18 68 62 (mobile)
Email: gustaf.edgren@ki.se

Professor Olof Nyrén
Tel: +46 (0)70-742 80 20
Email: olof.nyren@ki.se

Press Officer Katarina Sternudd
Tel: +46 (0)8-524 838 95 or +46 (0)70-224 38 95 (mobile)
Email: katarina.sternudd@ki.se