Radiation Pneumonitis and Fibrosis Following Split-Course Radiation Therapy for Lung Cancer: A radiologic and physiologic study

Abstract

Radiographic signs of radiation pneumonitis and fibrosis were assessed and pulmonary function monitored in lung cancer patients after two different split-course radiation therapy schedules, one with a rest interval of 3 weeks and the other with a rest interval of 5 weeks, the total radiation dose being the same in both treatments (55 Gy/20 fractions/7 or 9 weeks). Post-mortem findings were analysed when available. Spirometric measurement of vital capacity, determination of diffusing capacity for carbon monoxide (D_L) and alveolar volume with the single breath technique, and determination of regional distribution of lung perfusion by two different techniques, radiospirometry and gamma camera digital display following intravenous injection of ¹³³Xe, were carried out before and at various times after the completion of irradiation. Of the physiologic parameters, only D_L showed a significant decrease 6 as well as 9 months post-treatment (p<0.05). No difference between the two treatment schedules could be shown with regard to grade or time pattern of radiologic changes or decrease in D_L. The findings suggest that measurement of D_L may be of value in monitoring patients included in research protocols for radiation therapy of lung cancer as well as in selection of patients for this treatment.