Effect of concurrent radiation therapy and chemotherapy on pulmonary function in patients with esophageal cancer: Ddose-volume histogram analysis

PURPOSE The pulmonary effects of concurrent radiation therapy and chemotherapy were studied in patients enrolled in a phase I trial for esophageal cancer. MATERIALS AND METHODS Pulmonary function tests were performed prospectively before and after combined-modality therapy (oxaliplatin, 5-fluorouracil, and radiation therapy) in 20 patients with esophageal cancer. Cumulative and differential lung DVH analysis from 0 to 5400 cGy in 25-cGy intervals was performed for the last 15 patients. Correlation between radiation exposure in various dose ranges and percent reduction in pulmonary function tests was calculated as an exploratory analysis. RESULTS Significant reductions in carbon monoxide diffusion capacity corrected for hemoglobin (12.3%) and total lung capacity (2.5%) were evident at a median of 15.5 days after radiation therapy. DVH analysis revealed that the single dose of maximum correlation between lung volume radiation exposure and lung function reduction was less than 1000 cGy for all pulmonary functions. The percent lung volume that received a total dose between 700 and 1000 cGy maximally correlated with the percent reductions in total lung capacity and vital capacity, and the absolute lung volume that received a total dose between 700 and 1000 cGy maximally correlated with the percent reductions in total lung capacity, vital capacity, and carbon monoxide diffusion capacity. DISCUSSION Significant declines in carbon monoxide diffusion capacity and total lung capacity are evident immediately after the administration of conformal radiation therapy, oxaliplatin, and 5-fluorouracil for esophageal cancer. Other lung functions remain statistically unchanged. The percent or absolute lung volume that received a total dose between 700 and 1000 cGy may be significantly correlated with the percent decline of carbon monoxide diffusion capacity, total lung capacity, and vital capacity. These associations will be evaluated further in a follow-up study.