Pulmonary Function After Whole Lung Irradiation in Pediatric Patients with Solid Malignancies

Background: Although whole lung irradiation is used to treat pulmonary metastases of pediatric solid malignancies, few studies have addressed its long-term pulmonary consequences.

Methods: The authors conducted a retrospective study of longitudinal changes in 171 pulmonary function tests (PFTs) and their relation with clinical features in 48 survivors of pediatric malignant solid tumors treated with whole lung irradiation.

Results: Although active respiratory symptoms were seen in only 9 patients (18.8%), abnormalities in forced vital capacity (FVC; 58.3%), forced expiratory volume in 1 second (FEV(1) ; 64.6%), total lung capacity (TLC; 72.9%), and diffusion capacity of the lung for carbon monoxide corrected for hemoglobin (DLCO(corr) ; 70.8%) were common. At a median follow-up of 9.7 years after whole lung irradiation, FVC, FEV(1) , and TLC significantly declined longitudinally (P = .04, .03, and .02, respectively). Focal pulmonary boost irradiation was significantly associated with abnormal FEV(1) /FVC (P = .03), forced expiratory flow between 25% and 75% forced vital capacity (P = .005), residual volume (RV; P = .005), and RV/TLC (P = .002). Ten patients had baseline PFTs, and FVC, FEV(1) , TLC, and DLCO(corr) worsened immediately after radiation, followed by transient improvement but subsequent decline. Thirteen of 32 (40.6%) patients aged >18 years were smokers.

Conclusions: Pulmonary dysfunction was prevalent after whole lung irradiation and worsened over time, although most patients were asymptomatic. Boost irradiation impaired pulmonary function, and a significant proportion of patients were smokers. Further studies are planned to assess the predictors and clinical consequences of progressive PFT abnormalities and to evaluate educational interventions.