Effect of blood transfusions on immune function: IV. Effect on tumor growth.

Blood transfusions have previously been shown in retrospective studies of oncologic surgical patients to be associated with an increased incidence of tumor metastases and decreased long-term survival rate. The possibility that these findings were due to patients with larger, more aggressive tumors requiring the transfusions could not be excluded. To eliminate this possibility, the effect of transfusions on tumor growth in a rat sarcoma model was tested. In this study it was shown that allogeneic transfusions increase the rate of tumor growth and decrease mean survival times. This effect was not demonstrated when syngeneic transfusions were used. These data indicate that the diminished long-term survival seen in transfused patients undergoing tumor resection may be due to an impaired immunologic response to the tumor. Avoidance of this effect might be possible through the use of human syngeneic (autologous) transfusions.