Impact of dose-volume parameters on radiation-induced late pericardial effusion

Abstract

Objective To evaluate the impact of dose-volume parameters on the incidence of radiation-induced late pericardial effusion in patients with thoracic cancer. Methods Contrast-enhanced chest CT and echocardiography were applied in 49 patients with thoracic cancer who received radiotherapy to investigate the incidence of radiation-induced late pericardial effusion. The heart dose-volume parameters were analyzed to explore the physical influencing factors for radiation-induced late pericardial effusion. Results During the observation period, the incidence rate of radiation-induced late pericardial effusion was 28. 6% (14/49) , which included 12 patients with small amount and 2 patients with medium amount of pericardial effusion. The V30 and V35 of the heart were significantly higher in patients with radiation-induced pericardial effusion than in patients without (P = 0. 035 and 0. 038, respectively). Multivariate analysis showed that the V30 of the heart was the influencing factor for radiation-induced late pericardial effusion (P = 0. 036). The receiver operating characteristic ( ROC) curve was used to determine the appropriate threshold for V30. The area under the ROC curve was 0. 695, the accuracy of prediction was close to medium level, and the cut-off value was 33.0%. The incidence rate of radiation-induced late pericardial effusion in patients with 33.0% or greater V30 of the heart was significantly higher than that in patients with less than 33.0% V30 (43. 5% vs. 15. 4%, P=0.030). The sensitivity and specificity of prediction using V30 were both 71. 4%. Conclusions Pericardial effusion is a common manifestation of radiation-induced late heart damage. The incidence of pericardial effusion is associated with V30 and V35 of the heart, and V30 is the influencing factor. Increased sample size is needed to validate the results and reach a final conclusion. Key words: Pericardial effusion; Dose-volume histogram; Receiver operator characteristic curve; Thoracic neoplasms/radiotherapy