Purpose: To evaluate the importance of fractionating total body irradiation (TBI) in patients receiving an allogenic bone marrow transplant (BMT) for an acute myeloblastic leukemia (AML) in first complete remission (CR1).
Methods and materials: Between 1983 and 1990, 171 consecutive patients received either single dose TBI (STBI) (n = 65) or fractionated TBI (FTBI) (n = 106) after being conditioned with cyclophosphamide and before receiving a non-T-depleted Human Leucocyte Antigen (HLA)-identical marrow. Both groups were comparable except for date of BMT and diagnosis-to-BMT interval (D-BMT).
Results: After 63 months median follow-up, transplant-related mortality (TRM), probability of relapse, and 5-year disease-free survival (DFS) were 0.38 and 0.27 (p = 0.04), 0.29 and 0.26 (p = 0.22), 0.43 and 0.56 (p = 0.06), respectively, for STBI and FTBI. The supposed influence of the schedule of TBI disappeared in the multivariate analysis: TRM was enhanced by severe acute graft vs. host disease (p = 0.0002), early years of transplant (before January 1, 1987) (p = 0.0003), and longer D-BMT intervals (p = 0.038). Relapse was linked to early years of transplant (p < 0.00001), and the absence of chronic GVHD (p = 0.007). Longer DFSs were observed for later years of transplant (after January 1, 1987 and later) (p = 0.001), milder acute GVHD (p = 0.005), and shorter D-BMT intervals (p = 0.045). Important improvements of the results were made during the 7-year observation period: TRM, probability of relapse, and DFS were, respectively, 0.36, 0.28, and 0.46 for patients transplanted before January 1, 1987 vs. 0.21, 0.15, and 0.67 after that date.
Conclusion: Our data strongly suggest that allogenic BMT is the best postremission treatment for AML in CR1, and the results are better when BMT shortly follows the achievement of remission. The schedule of TBI was of little importance compared with the improvements made in the management of patients undergoing BMT during the 1980s, and, therefore, reports concerning data prior to 1985 should be interpreted cautiously.