Pulmonary Toxicities in Pediatric Patients Treated With Total Body Irradiation Using the Lateral Opposed Fields Technique

ABSTRACT Purpose Pulmonary toxicity (PT) remains a concern following total body irradiation (TBI). This study describes the incidence and factors associated with PT in a cohort of patients homogeneously treated with the lateral opposed fields technique. Methods Medical records of 61 patients ≤21 years of age treated with TBI as a component of stem cell transplantation from 1993–2017 were retrospectively reviewed. The incidences of PT, graft‐versus‐host disease (GVHD), and other toxicities were recorded for each patient. PT was subdivided into its etiologies, and symptomatic PT was established by clinical diagnosis. The association of PT with other variables was examined using chi‐square tests, and overall survival (OS) was estimated using Kaplan–Meier. Results Three‐year OS was 65% (54%–79%). Median TBI dose rate was 7.7 cGy/min (4.0–10 cGy/min). PT occurred in 20 patients (33%). A higher rate of PT was observed in patients with GVHD (65% vs. 35%, p  ≤ 0.01). TBI dose rate (</≥ 7.7 cGy/min) was not associated with the risk of PT; however, on continuous analysis, a higher dose rate increased the risk of PT (HR = 1.9, p = 0.04). PT (HR = 3.4, p = 0.01), noninfectious PT (HR = 5.0, p  ≤ 0.01), and pneumonitis (HR = 4.3, p = 0.01) were associated with inferior OS. Conclusions This cohort of patients treated with a low dose rate, bilateral technique, and total dose of 1000–1320 cGy experienced an acceptable incidence of PT, comparable to other published studies. Because PT correlated with reduced survival, current practice should seek to address factors associated with PT by aiming to prevent GVHD and by choosing low dose rates, such as in the range of 4.0–10 cGy/min.