Dosimetric predictors of radiation-induced pericardial effusion in esophageal cancer

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 V 5 –V 55 , mean pericardium dose, and pericardium V 5 –V 50 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 V 50 and pericardium D 10 significantly affected the incidence of SPE. The pericardium V 50 in patients with SPE ranged from 17.1 to 21.7%. Factors affecting the incidence of SPE were the V 50 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 V 50 ≤ 17% is important to avoid symptomatic PE in esophageal cancer patients treated with concurrent chemoradiotherapy.