Regional lung function impairment following post-operative radiotherapy for breast cancer using direct or tangential...

We have compared the effect of tangential and direct irradiation on regional lung function in 22 consecutive patients with breast cancer, who had been treated by post-operative irradiation 3 months prior to the examination. The tangential technique (total dose 32-36 Gy, less than 5 Gy of the lung) was employed in eight of the patients, while the direct technique (total dose 40 Gy, 5-20 Gy to the lung) was used in the other 14. In the group that had been treated by the tangential technique, there was no impairment of the ventilation or perfusion of the irradiated lung compared with the contralateral lung. The radiographs of the thorax were all normal. In the group that had been treated by the direct technique, there was a reduction in both the ventilation and the perfusion in 12 of the patients (p less than 0.01). The radiographs of the thorax were abnormal in only seven of these 12 patients. In both groups the regional leakiness of the lungs was evaluated as the pulmonary clearance of inhaled nebulised 99Tcm-DTPA. Due to differences in smoking habits between and within the groups, the results were not conclusive. It is concluded that the regional lung function was not significantly affected by the tangential technique, in contrast to a pronounced and harmful effect of the direct technique.