Phenotyped Blood Reduces Alloimmunization Rates Among Cancer Patients

Alloimmunization against RBC antigens is a complication of blood transfusion/pregnancy that may cause hemolytic transfusion reactions and can difficult compatible blood availability in future transfusions. Frequency of transfusion, as well as patient's age, type of illness and treatment may influence the development of alloantibodies. Alloimmunization rates of 3.4% in hospitalized patients have been reported. The main purpose of this study is to compare the frequency of alloimmunization to red blood cell antigens in cancer patients that were transfused with phenotyped blood with those who were not.

Transfusion medical records of 669 oncologic patients were analyzed. Patients were evaluated by cancer type, number of transfusions, presence of alloantibodies and its clinical significance. Antibody screening and identification to red cell antigens were performed using gel-test (Diamed S/A, Lagoa Santa Brazil). All hematological patients were phenotyped for Rh (C, c, E, e, Cw) and K1 antigens using gel-test (Diamed S/A). Patients with hematological diseases were exclusively transfused with RBC units also matched for Rh/K1 antigens. Patients with other types of cancer were transfused with non-phenotyped RBC units. Patients that were previously immunized were excluded from the study.

Of 2,781 transfusions in 669 oncology patients, 1,026 were performed using phenotyped matched RBC units for Rh and K1 antigens. Patients with hematological diseases were more transfused when compared to patients with other types of cancer (p<0.001). However, alloimmunization rate found in patients that were transfused with phenotyped RBC units was statistically significant lower (1.026/1,000 transfusions) when compared to those one non-phenotyped blood (7.98/1,000 transfusions), (p=0.015). Moreover, the relative risk of a cancer patient to develop RBC alloantibodies when transfused with non-phenotyped Rh and Kell RBC units is 2.519 (IC 95%=2.181-2.908).

Conclusion: The rate of alloimmunization was statistically higher in patients that were transfused non-phenotyped RBC, even though this group was less transfused. We conclude that phenotyping RBC for Rh and K1 antigens reduces alloimmunization among cancer patients and prevents future complications when transfusing them.

No relevant conflicts of interest to declare.