Myeloablative conditioning with total body irradiation for AML: Balancing survival and pulmonary toxicity

The purpose of this study was to compare leukemia-free survival (LFS) and other clinical outcomes in patients with acute myelogenous leukemia who underwent a myeloablative allogeneic stem cell transplant with and without total body irradiation (TBI).

Adult patients with acute myelogenous leukemia undergoing myeloablative allogeneic stem cell transplant at Duke University Medical Center between 1995 and 2012 were included. The primary endpoint was LFS. Secondary outcomes included overall survival (OS), nonrelapse mortality, and the risk of pulmonary toxicity. Kaplan-Meier survival estimates and Cox proportional hazards multivariate analyses were performed.

A total of 206 patients were evaluated: 90 received TBI-based conditioning regimens and 116 received chemotherapy alone. Median follow-up was 36 months. For all patients, 2-year LFS and OS were 36% (95% confidence interval [CI], 29-43) and 39% (95% CI, 32-46), respectively. After adjusting for known prognostic factors using a multivariate analysis, TBI was associated with improved LFS (hazard ratio: 0.63; 95% CI: 0.44-0.91) and OS (hazard ratio: 0.63; 95% CI, 0.43-0.91). There was no difference in nonrelapse mortality between cohorts, but pulmonary toxicity was significantly more common with TBI (2-year incidence 42% vs 12%, P < .001). High-grade pulmonary toxicity predominated with both conditioning strategies (70% and 93% of cases were grade 3-5 with TBI and chemotherapy alone, respectively).

TBI-based regimens were associated with superior LFS and OS but at the cost of increased pulmonary toxicity.