Prognostic CT features in patients with untreated thymic epithelial tumors

Abstract

To determine the prognostic CT features in patients with untreated thymic epithelial tumors (TETs). Clinical data and CT imaging features of 194 patients with pathologically confirmed TETs were retrospectively reviewed. The subjects included 113 male and 81 female patients between 15 and 78 years of age, with a mean age of 53.8 years. Clinical outcomes were categorized according to whether relapse, metastasis or death occurred within 3 years after the first diagnosis. Associations between clinical outcomes and CT imaging features were determined using univariate and multivariate logistic regression analyses, while the survival status was analyzed by Cox regression. In this study, we analyzed 110 thymic carcinomas, 52 high-risk thymomas and 32 low-risk thymomas. Percentages of poor outcome and patient death in thymic carcinomas were much higher than those in patients with high-risk and low-risk thymomas. In the thymic carcinomas groups, 46 patients (41.8%) experienced tumor progression, local relapse or metastasis and were categorized as having poor outcomes; vessel invasion and pericardial mass were confirmed to be independent predictors by logistic regression analysis (p < 0.01). In the high-risk thymoma group, 11 patients (21.2%) were categorized as having poor outcomes, and the CT feature pericardial mass was confirmed to be an independent predictor (p < 0.01). In survival analysis, Cox regression showed that CT features of lung invasion, great vessel invasion, lung metastasis and distant organ metastasis were independent predictors for worse survival in the thymic carcinoma group (p < 0.01), while lung invasion and pericardial mass were independent predictors for worse survival in high-risk thymoma group. No CT features were related to poor outcome and worse survival in the low-risk thymoma group. Patients with thymic carcinoma had poorer prognosis and worse survival than those with high-risk or low-risk thymoma. CT can serve as an important tool for predicting the prognosis and survival of patients with TETs. In this cohort, CT features of vessel invasion and pericardial mass were related to poorer outcomes in those with thymic carcinoma and pericardial mass in those with high-risk thymoma. Features including lung invasion, great vessel invasion, lung metastasis and distant organ metastasis indicate worse survival in thymic carcinoma, whereas lung invasion and pericardial mass indicate worse survival in high-risk thymoma.

Figure 1

Thymic squamous carcinoma in a 54-year-old man with vessel invasion and pericardial mass. Contrast enhanced CT scan (Axial 5.0 mm) obtained at the level of the aortic arch (A) and pulmonary trunk (B) shows the interface between the tumor and the left brachiocephalic vein was blurred and the lumen was quite narrowed and compressed (white arrow). A soft tissue mass was seen inside and around the pericardium (black arrow). This patient had tumor progression and died 43.9 months since the first CT examination.

Figure 2

The ROC curve of the multivariate logistical regression model. The area under curve (AUC) was 0.867 and 0.794 for the group of thymic carcinoma (A) and high-risk thymoma (B), respectively.

Figure 3

High-risk thymoma (type B2) in a 66-year-old man with pericardial mass and lung invasion. Contrast enhanced CT scan (Axial 5.0 mm) obtained at the level of the aortic root (A) and pulmonary trunk (B) shows tumor invading the pericardium and form large soft tissue mass inside the pericardium. The interface between the tumor and lung was lost, with compression and effusion in the lung (white arrow). This patient died 23.8 months since the first CT examination.

Figure 4

Thymic squamous carcinoma in a 27-year-old man withlung and liver metastasis. Contrast enhanced CT scan (Axial 5.0 mm) obtained at the level of the main bronchi (A) and the first porta hepatis (B) shows multiple metastasis in the bilateral lung and the left lobe of the liver (black arrow). This patient died 26.1 months since the first CT examination.