A study of more than 350,000 blood transfusion recipients showed that those who received blood from precancerous donors had no higher risk of developing cancer than other transfusion recipients.
Researchers say the findings are reassuring and a major advancement in the understanding of long-term transfusion-related risks.
"Continuous attention to transfusion safety has reduced the risk of transfusion-transmitted disease to a current record low," write researcher Gustaf Edgren, MD, of the Karolinska Institutet in Stockholm, Sweden, and colleagues. Although most infections and complications have been relatively easy to identify, the possible transmission of chronic diseases with unknown causes has been far more difficult to address, they write.
Blood Transfusions and Cancer Risk
The study analyzed data gathered between 1968 and 2002 from computerized blood bank registers in Denmark and Sweden, including information on 1.13 million blood donors and 1.31 million blood transfusion recipients.
Out of the more than 350,000 recipients included in the final analysis, just over 12,000 (3%) were exposed to blood products from donors who later went on to develop cancer.
The blood transfusion recipients were followed for up to 34 years, and the results showed no increased risk of cancer associated with the exposure.
"Our data provide no evidence that blood transfusions from precancerous blood donors are associated with an increased risk of cancer among recipients compared with transfusions from non-cancerous donors," the researchers conclude.
Thanks to the scope and thoroughness of the study, experts say the results represent an important step forward in evaluating one of the potential long-term risks of blood transfusion. But much more is still unknown.
"Blood is an immensely complex and biologically active substance. Although the potential for standard allogeneic blood transfusion [from unknown persons] to save lives is incontrovertible, our understanding of the full consequences of transfusion is rudimentary," writes Garth Utter, MD, of the University of California, Davis, in a commentary that accompanies the study in The Lancet.