Effect of lung irradiation on the incidence of pulmonary metastases and its mechanism.

LP-12 cells injected intravenously into ddY mice result in the formation of visible lung colonies which are introduced as a model for pulmonary metastases. Localized irradiation before tumour cell transplantation significantly increased the incidence of pulmonary metastases in the irradiated lung only. The changes of the vascular permeability of the lung indicate that dilatation of capillaries or increased permeability may be one of the main mechanisms of this phenomenon.