Dosimetric predictors of radiation-induced pericardial effusion in esophageal cancer.

ABSTRACT

PURPOSE: To evaluate the dose-volume parameters of the pericardium and heart in order to reduce the risk of radiation-induced pericardial effusion (PE) and symptomatic PE (SPE) in esophageal cancer patients treated with concurrent chemoradiotherapy. METHODS: In 86 of 303 esophageal cancer patients, follow-up CT was obtained at least 24 months after concurrent chemoradiotherapy. Correlations between clinical factors, including risk factors for cardiac disease, dosimetric factors, and the incidence of PE and SPE after radiotherapy were analyzed using Cox proportional hazard regression analysis. Significant dosimetric factors with the highest hazard ratios were investigated using zones separated according to their distance from esophagus. RESULTS: PE developed in 49 patients. Univariate analysis showed the mean heart dose, heart V5-V55, mean pericardium dose, and pericardium V5-V50 to all significantly affect the incidence of PE. Additionally, body surface area was correlated with the incidence of PE in multivariate analysis. Grade 3 and 4 SPE developed in 5 patients. The pericardium V50 and pericardium D10 significantly affected the incidence of SPE. The pericardium V50 in patients with SPE ranged from 17.1 to 21.7%. Factors affecting the incidence of SPE were the V50 of the pericardium zones within 3 cm and 4 cm of the esophagus. CONCLUSION: A wide range of radiation doses to the heart and pericardium were related to the incidence of PE. A pericardium V50 ≤ 17% is important to avoid symptomatic PE in esophageal cancer patients treated with concurrent chemoradiotherapy.