Impact of pulmonary metastases of the R1H-tumour on radiation tolerance of rat lung.
OBJECTIVE
The aim was to investigate the influence of pulmonary metastases of the rhabdomyosarcoma R1H on the radiation response of the lung of the WAG/Rij rat.


METHODS
Three groups of animals were investigated: metastases-free animals treated with fractionated irradiation of the lungs; metastases-bearing animals receiving no irradiation; and metastases-bearing animals treated with fractionated irradiation initiated 14, 21 or 28 days after induction of pulmonary metastases of the R1H-tumour by i.v. injection of viable tumour cells. Metastases were thus treated at various well-defined sizes. Total doses of 20-60Gy were applied in fractions of 2 Gy within 11 days. Complication rate and survival time were used as endpoints.


RESULTS
About 2 months after onset of irradiation treatment, animals had to be sacrificed because of severe respiratory distress either caused by irradiation-induced lung damage (median 57 days, range 36-77 days), or because of development of lung metastases (65, 20-160 days). A decrease of the ED(50) (dose required to induce lethal lung damage in 50% of irradiated animals) was determined for metastases-bearing animals. This effect increased with metastatic volume.


CONCLUSIONS
The results suggest that the presence of tumours in the lung decreased the lung tolerance to radiation. This effect can hardly be explained by a reduction in functional lung volume by metastatic volume.
Raabe
A
A
Department of Radiotherapy and Radiooncology, University of Hamburg, Martinistr. 52, D-20246, Hamburg, Germany. araabe@uke.uni-hamburg.de
Beck-Bornholdt
H P
HP
Krüll
A
A
Zieron
J O
JO
Alberti
W
W
D000818:Animals; D005260:Female; D008168:Lung / Q000528:radiation effects*; D008175:Lung Neoplasms / Q000556:secondary*; D008297:Male; D011836:Radiation Tolerance; D051381:Rats; D012208:Rhabdomyosarcoma / Q000532:radiotherapy*; D016212:Transforming Growth Factor beta / Q000096:biosynthesis
D016212:Transforming Growth Factor beta