The Correlation of the World Health Organization Histologic Classification of Thymic Epithelial Tumors and Its Prognosis: A Clinicopathologic Study of 108 Patients From China

Diagnostic and prognostic value of FDG PET-CT in patients with suspected recurrent thymic epithelial tumors

This study aimed to evaluate the diagnostic and prognostic value of FDG PET/CT in patients with suspected recurrent thymic epithelial tumors (TETs). We retrospectively reviewed 83 patients with histopathologically proven TETs (50 thymomas; 33 thymic carcinomas) who underwent FDG PET/CT after surgery. The sensitivity and specificity of FDG PET/CT in detecting recurrence were calculated. The progression-free survival rate (PFS) was calculated by the Kaplan-Meier method. FDG PET/CT results were positive in 50 patients and negative in 33. Recurrent TETs were confirmed in 40 of 50 patients with positive PET/CT findings. The sensitivity and specificity of FDG PET/CT were 100% and 76.7%, respectively. Disease progression occurred in 28 patients during the follow-up. FDG PET/CT showed added prognostic value over the Masaoka stage and histopathology. Among patients with the same Masaoka stage, negative PET/CT was significantly associated with better PFS (P < 0.001). Similarly, among patients with the same histopathology, negative PET/CT was also associated with a significantly longer PFS (P < 0.001). FDG PET/CT demonstrated a good diagnostic performance in patients with recurrent TETs and had an important prognostic value in assessing the risk of disease progression.

Predicting subtypes of thymic epithelial tumors using CT: new perspective based on a comprehensive analysis of 216 patients

It is highly necessary to identify low versus high risk thymic epithelial tumors (TETs) before operation to guide optimal treatment strategies. Current CT diagnostic parameters could not effectively achieve this goal. We evaluated three parameters of CT scan in a cohort of 216 TETs patients. Parameters of contrast enhancement, risk of aggressiveness, and nodule with fibrous septum were evaluated in low (A, AB) versus high risk (B1, B2, B3 and thymic carcinoma) TETs. Grade of contrast enhancement showed predictive value in classifying low and high risk TETs well. A maximal contrast-enhanced range of 25.5 HU could produce 78.8% sensitivity and 68.5% specificity in determining low risk subtypes. Additionally, risk of aggressiveness parameter was demonstrated to be associated with TETs subtype (r = 0.801, P < 0.001) and may add confidence in determining low versus high risk subtypes. Furthermore, multiple nodule with fibrous septum could suggest subtype AB. Findings from this study support role of studied parameters of CT manifestations in predicting the low and high risk stages of TETs. These findings provide empirical evidence for incorporating these parameters in clinical practice for identifying TETs stage before operation, if validated in additional studies.

Protein expression status of p53 and epidermal growth factor receptor in thymoma

Evaluating the state of malignancy of thymoma is a challenge due to the discrepancies between pathological classifications and clinical stage criteria. Therefore, the identification of markers contributing to the assessment of the stage of malignancy of thymoma would be useful. This study aimed to evaluate the prevalence of p53 and epidermal growth factor receptor (EGFR) in thymoma, demonstrate the clinical significance and assess the potential of specific-targeted therapy. A total of 16 thymic hyperplasia patients and 43 thymoma patients were included in the study. Samples were tested for the expression of p53 and EGFR using immunohistochemistry. In the multivariate analysis, the thymoma cases were followed up to analyze the relationship between survival rates and a number of potential factors, such as p53 and EGFR. There were 21 completely resected stage II cases which were evaluated for relapse-free time. The distribution of p53 with clinicopathological parameters was: type A/AB 57.1%, type B1 85.7%, type B2 85.7%, type B3 90.9% and type C 100%; and stage I 90.9%, stage II 90.9%, stage III 100% and stage IV 100%. The EGFR-positive rates were: type A/AB 42.9%, type B1 71.4%, type B2 57.1%, type B3 90.9% and type C 100%; and stage I 45.5%, stage II 76%, stage III 75% and stage IV 100%. EGFR expression correlated with tumor size, pathological classification and advanced clinical stage, whereas p53 correlated only with pathological classifications. Findings of our multivariate analysis showed that neither p53 nor EGFR are independent prognostic factors. Nevertheless, the fact that a statistical difference (p<0.05) was noted in relapse-free survival time between the EGFR-positive and EGFR-negative groups (48.182±33.757 vs. 76.3±10.339 months) suggests that EGFR plays a key role in thymoma progression. No positive results were found between the p53 groups following a survey conducted to assess relapse time. Therefore, the application of EGFR-targeting agents is warranted in invasive thymoma, whereas the targeting of p53 has yet to be elucidated.

DNA methylation in thoracic neoplasms

Thoracic neoplasms, which include lung cancers, esophageal carcinoma, and thymic epithelial tumors, are the leading causes of tumor-related death and a major health concern worldwide. The development of neoplasms is a multistep process involving both genetic and epigenetic alterations. A growing body of research provides evidence that aberrant DNA methylation, including DNA hypermethylation in promoter regions, global DNA hypomethylation and the overexpression of DNA methyltransferases, plays an important role in tumorigenesis. In this review, we summarize published observations of methylation pattern disruptions in thoracic tumors, and discuss how these abnormalities contribute to the development of cancers. We review recent findings showing that suppressing the activity of the DNA methylating enzymes DNMTs can have potent anti-cancer effects, and discuss the possibility of developing novel therapies for thoracic tumors based on DNMT inhibition.