High-dose radioimmunotherapy versus conventional high-dose therapy and autologous hematopoietic stem cell transplantation for relapsed follicular non-Hodgkin lymphoma: a multivariable cohort analysis

We performed a multivariable comparison of 125 consecutive patients with follicular lymphoma (FL) treated at our centers with either high-dose radioimmunotherapy (HD-RIT) using I-131-anti-CD20 (n = 27) or conventional high-dose therapy (C-HDT) (n = 98) and autologous hematopoietic stem cell transplantation. The groups were similar, although more patients treated with HD-RIT had an elevated pretransplantation level of lactate dehydrogenase (41% versus 20%, P = .03) and elevated international prognostic score (41% versus 19%, P = .02). Patients treated with HD-RIT received individualized therapeutic doses of I-131-tositumomab (median, 19.7 GBq [531 mCi]) to deliver 17 to 31 Gy (median, 27 Gy) to critical organs. Patients treated with C-HDT received total body irradiation plus chemotherapy (70%) or chemotherapy alone (30%). Patients treated with HD-RIT experienced improved overall survival (OS) (unadjusted hazard ratio [HR] for death = 0.4 [95% confidence interval (95% CI), 0.2-0.9], P = .02; adjusted HR, 0.3, P = .004) and progression-free survival (PFS) (unadjusted HR = .6 [95% C.I., 0.3-1.0], P = .06; adjusted HR, 0.5, P = .03) versus patients treated with C-HDT. The estimated 5-year OS and PFS were 67% and 48%, respectively, for HD-RIT and 53% and 29%, respectively, for C-HDT. One hundred-day treatment-related mortality was 3.7% in the HD-RIT group and 11% in the C-HDT group. The probability of secondary myelodysplastic syndrome/acute myeloid leukemia (MDS/AML) was estimated to be .076 at 8 years in the HD-RIT group and .086 at 7 years in the C-HDT group. HD-RIT may improve outcomes versus C-HDT in patients with relapsed FL. (C) 2003 by The American Society of Hematology.