Pulmonary disease after treatment for Wilms tumor: a report from the national wilms tumor long-term follow-up study.
The effect of whole lung irradiation on lung function was investigated in 48 children treated for Wilm's tumour with pulmonary metastases. Lung function tests were performed before irradiation and were repeated annually for as long as possible, the length of follow-up varying from two to 17 years. A reduction in both lung volume and in dynamic compliance was clearly observed. In some patients these changes occurred in the early post-irradiation months, but in most the decrease observed progressed over longer periods of time. Static pressure volume curves, bloodgases, and carbon monoxide transfer were normal. These findings make it unlikely that postirradiation pulmonary fibrosis was involved. Another explanation for the decreased lung volume and dynamic compliance might be failure of alveolar multiplication. Muscular injury is unlikely as the patients were able to produce normal transthoracic pressures. A failure of chest wall growth is also possible and would explain the progressive restrictive impairment but not the early lung function changes. It is suggested that the early effects detected in some patients were the result of lung injury and that later effects resulted from impaired chest wall growth. Although the effects of pulmonary irradiation on lung function have been extensively investigated in adults, reports on the effects on respiratory function of whole lung irradiation are relatively few and there have been no reports of detailed, repeated lung function tests after this type of irradiation. In contrast to adults, young children are in a period of rapid lung and skeletal growth and the effect of pulmonary irradiation might be a failure of alveolar development resulting from impaired cellular proliferation, thus decreasing the number of alveoli. The aim of this study was to detect the shortand long-term pulmonary function changes in young children who received whole lung irradiation at doses which were therapeutically efficient but close to tolerance and we have tried to characterise the physiopathological mechanisms of the changes observed. Actinomycin D which enhances the effects of irradiation, was administered consecutively.1 Address for reprint requests: Dr MR Benoist, Laboratoire d'Exploration Fonctionnelle Respiratoire, Service du Pr J Paupe, H6pital des Enfants Malades, 149 rue de Sevres, 75730 Paris Cedex 15, France. Methods Forty-eight children undergoing treatment for Wilm's tumour associated with pulmonary metastases at the Institut Gustave Roussy between 1960 and 1976 were studied. Clinical and therapeutic characteristics are summarised in table 1. In 39 of these patients, nephrectomy was followed by irradiation of the tumour bed, including the entire width of the spine, the field extending to the hemidiaphragm. All the children received bilateral pulmonary irradiation using 60Co at a dose of 20 Grays/three weeks. Actinomycin D was always given in conjunction. Twenty-two patients were studied prospectively with initial lung function testing carried out just before pulmonary irradiation and this was denoted test "O". This information was lacking for the other 26 children who were included in the study which began in 1973. All 48 patients were subsequently tested in the same way. Measurements of lung function were repeated in each patient every six months during the first two years after pulmonary irradiation and then annually for as long as possible, 175 group.bmj.com on June 25, 2017 Published by http://thorax.bmj.com/ Downloaded from