Lung function of children treated for malignant extrapulmonary tumors.

Lung function was studied in 29 children suffering from extrapulmonary tumors of varying etiology (Wilm's tumor, n = 7; bone malignancy, n = 17; nasopharyngeal epithelioma, n = 5). Lung volume: vital capacity (VC) and functional residual capacity (FRC), lung mechanics: lung resistance (RL), dynamic lung compliance (CLdyn) and static lung compliance (CLstat) and lung transfer factor for CO (TLCO), and blood gases were determined at different stages of therapy: at t0, before any aggressive treatment for respiratory function; at t1, after the initiation of polychemotherapy with or without local tumoral treatment (surgery or local irradiation); at t2, less than 6 months after onset of thoracopulmonary irradiation (whole lung irradiation at 20 grays) (group I), or local thoracopulmonary irradiation at high exposure greater than 40 grays (group II); at t3 after more than 6 months following irradiation with chemotherapy maintained; at t4, after cessation of all treatment (mean: 25 months +/- 14 after cessation of treatment). At t0, lung function data in children without pulmonary metastases did not deviate from predicted values. At t1, group I showed a significant decrease in CLdyn, which could be due to chemotherapy and for 5 children to consequences of abdominal surgery. In group II, only two children had a low CLdyn and also a significant decrease in VC (possibly due to the site of the tumor). After irradiation (at t2), FRC, TLCO and CLdyn were significantly lower than the predicted values and lower than at t1 in both groups (p greater than 0.01). At t3, functional parameters did not show any change compared to t2. At t4, FRC and TLCO were within normal limits in both groups but CLdyn, CLstat and the CLdyn/FRC ratio remained significantly decreased. It is suggested that these functional abnormalities are due to inadequate alveolar growth.