Blood transfusion and tumor growth.

The definitive study of the relationship between blood transfusion and cancer recurrence has not been published. The existing studies fail to adequately control for anemia, duration of surgery, magnitude of the procedure, blood loss, and stage of disease, variables that are related to the administration of blood and are also associated with cancer recurrence. None of the negative studies has the number of patients necessary to achieve statistical validity. Experimental studies indicate that tumor growth may be inhibited or promoted by allogeneic blood transfusion depending on the route and timing of the transfusion relative to tumor inoculation, the route of tumor inoculation and the specific tumor used, and the strain and species of the animal and blood donor. The available evidence suggesting a relationship between blood transfusion and cancer recurrence does not support any changes in the use of blood for patients with malignancies.