Lethal pulmonary complications significantly correlate with individually assessed mean lung dose in patients with hematologic malignancies treated with total body irradiation

Abstract

Purpose : To assess the impact of lung dose on lethal pulmonary complications (LPCs) in a single-center group of patients with hematologic malignancies treated with total body irradiation (TBI) in the conditioning regimen for bone marrow transplantation (BMT). Methods : The mean lung dose of 101 TBI-conditioned patients was assessed by a thorough (1 SD around 2%) in vivo transit dosimetry technique. Fractionated TBI (10 Gy, 3.33 Gy/fraction, 1 fraction/d, 0.055 Gy/min) was delivered using a lateral-opposed beam technique with shielding of the lung by the arms. The median lung dose was 9.4 Gy (1 SD 0.8 Gy, range 7.8–11.4). The LPCs included idiopathic interstitial pneumonia (IIP) and nonidiopathic IP (non-IIP). Results : Nine LPCs were observed. LPCs were observed in 2 (3.8%) of 52 patients in the group with a lung dose ≤9.4 Gy and in 7 (14.3%) of 49 patients in the >9.4 Gy group. The 6-month LPC risk was 3.8% and 19.2% ( p = 0.05), respectively. A multivariate analysis adjusted by the following variables: type of malignancy (acute leukemia, chronic leukemia, lymphoma, myeloma), type of BMT (allogeneic, autologous), cytomegalovirus infection, graft vs. host disease, and previously administered drugs (bleomycin, cytarabine, cyclophosphamide, nitrosoureas), revealed a significant and independent association between lung dose and LPC risk ( p = 0.02; relative risk = 6.7). Of the variables analyzed, BMT type ( p = 0.04; relative risk = 6.6) had a risk predictive role. Conclusion : The mean lung dose is an independent predictor of LPC risk in patients treated with the 3 × 3.33-Gy low-dose-rate TBI technique. Allogeneic BMT is associated with a higher risk of LPCs.