RATE OF MARROW ENGRAFTMENT DOES NOT APPEAR TO BE ADVERSELY AFFECTED BY EARLY MARROW INFUSION AFTER TOTAL-BODY IRRADIATION

Bone marrow transplantation (BMT) provides a means of increasing chemo-radiotherapy doses beyond the limits imposed by marrow toxicity. The time interval between myeloablative therapy and marrow infusion needs to be optimized to ensure prompt engraftment. It has been suggested that early marrow infusion after completion of total body irradiation (TBI) may be detrimental to rapid marrow reconstitution. Hence a retrospective analysis of 75 BMT patients was performed to document the rate of marrow engraftment following marrow infusion given immediately after TBI. Engraftment rates (time to absolute neutrophil count to greater than 0.5 x 10(9)/L) of patients receiving different conditioning regimens were compared. Results show similar engraftment rates in patients receiving bone marrow infusion 27.7 and 32.1 hours after completion of chemotherapy in autologous (20.5 days) and allogeneic (18.5 days) transplants respectively, or 2.9 and 2.0 hours after completion of TBI in autologous (20.1 days) and allogeneic (19.4 days) transplants respectively. These results are similar to those reported for delayed marrow infusion after TBI and would support that early marrow infusion after TBI does not adversely influence rate of engraftment. Thus it appears appropriate to give marrow immediately after completion of TBI.