Comparison of two total body irradiation regimens in allogeneic bone marrow transplantation for acute non-lymphoblastic leukemia in first remission

Between November 1976 and December 1987, 84 patients with newly diagnosed acute non-lymphoblastic leukemia who had achieved complete remission underwent non T-cell depleted allogeneic bone marrow transplantation from Human Leukocyte Antigen-Mixed Lymphocyte Culture (HLA-MLC) matched sibling donors. The first 36 patients (November 1976-June 1983) were prepared with cyclophosphamide sibling donors. The first 36 patients fraction total body irradiation with 750 cGy at a dose rate of 26 cGy/minute (Group I). The next 48 patients (July 1983-December 1987) were prepared with similar chemotherapy, but received hyperfractionated total body irradiation with total 1320 cGy, 165 cGy twice a day at a dose rate of 10 cGy/minute (Group II). Patient characteristics between these two groups are similar except for the significantly older age distribution in Group II. Median follow-up of Groups I and II are 8 years and 11 months and 2 years and 3 months, respectively. The Kaplan-Meier relapse-free survival, survival, and relapse rates at 3 years are 56, 58, and 19% in Group I and 69 (p = 0.22), 77 (p = 0.07), and 10% (p = 0.37) in Group II. There is no difference in the incidence of interstitial pneumonitis, viral or idiopathic, engraftment rate, or incidence of graft versus host disease (GVHD) between these two groups. The fractionated total body irradiation treated group had significantly less nausea and vomiting. Multivariate analysis shows that total body irradiation regimen is not a significant factor in regard to relapse rate, relapse-free survival, and survival.