CT Density in Lung Cancer Patients After Radiotherapy Sensitized by Metoclopramide: A Subgroup Analysis of a Randomized Trial

Purpose: To investigate the lung tissue response measured with computed tomography (CT) after radiotherapy (RT) combined with metoclopramide. Patients and Methods: Patients with non-small cell lung cancer (tumor stage IIIA and IIIB), included in a multicenter, randomized phase III trial investigating the use of metoclopramide as a radiosensitizing agent, were examined with repetitive post-RT CT scans. The analysis comprised data up to 100 days after RT for a subgroup of 16 patients treated with a total dose of 60 Gy given in 1.82 Gy per fraction. Results: Large radiation doses to subvolumes were associated with denser lung tissue measured with CT (p < 0.001). Opposed to this finding, the volume of lung tissue irradiated with significant doses (V 40Gy ) was negatively correlated with the average increase in lung tissue density (p = 0.003). Patients randomized to metoclopramide injections also experienced less increase in lung tissue density (p = 0.01). Conclusion: There was an increase in the density of irradiated lung tissue with radiation dose and time after RT. Metoclopramide and significant radiation doses to larger lung volumes (V 40Gy ) seemed to protect against fibrosis development.