Total thymectomy for thymic lymphoepithelioma-like carcinoma-report of two cases

Clinical features and treatment outcome of lymphoepithelioma-like carcinoma from multiple primary sites: a population-based, multicentre, real-world study

BACKGROUND

Lymphoepithelioma-like carcinoma (LELC) is a rare and unique subtype of cancer that histologically resembles undifferentiated nasopharyngeal carcinoma (NPC). The population-based analysis of LELC and the optimal treatment remains unclear.

MATERIALS AND METHODS

This real-world, retrospective study investigated 770 patients with LELC for primary site, treatment, and survival outcomes from 2005 to 2019 from five cancer centres in China. The overall survival (OS) of different subgroups was appraised by log-rank tests and Kaplan-Meier analysis.

RESULTS

Primary sites LELC included the lung (597 cases, 77.5%), salivary gland (115 cases, 14.9%), and others. The median progression-free survival (PFS) of LELC patients was 47.4 months. The median overall survival (OS) was not reached. The 5-year survival rate for LELC patients was 77.8%. Most patients in stages I and II received surgery. The majority of patients in stage III received surgery and radiotherapy. More than half of the patients in stage IV received chemotherapy. Among relapsed or metastatic cases receiving chemotherapy, patients who received immunotherapy at any time presented with a superior OS than those without immunotherapy (P < 0.0001, HR = 0.39, 95% CI 0.25-0.63). Compared with the SEER database, patients with LELC had a better prognosis than NPC, with a 5-year overall survival of 77.3% vs. 56.8% (P < 0.001).

CONCLUSION

Our data provide treatment patterns and outcomes for LELC from various primary sites. Randomized controlled studies are necessary to further define the standard of care for patients with LELC. Trial registration This clinical trial was registered at ClinicalTrials.gov (No. NCT04614818).

Thymic Lymphoepithelial Carcinoma Associated with Epstein-Barr Virus: Experiences and Literature Review

Thymic lymphoepithelial carcinoma (TLEC) is a primary thymic carcinoma that accounts for about 14% of all thymic epithelial tumors and is classified into 14 types. The histological morphology is similar to lymphoepithelioma, a type of undifferentiated nasopharyngeal carcinoma. It has been reported that squamous carcinoma accounts for approximately 80% of thymic carcinoma, followed by TLEC, which accounts for 6%. TLEC has been reported to be associated with Epstein-Barr virus (EBV), with EBV infection in TLEC tumor cells first noted by Lyvraz et al. in 1985. Tumors shown to be EBV-positive are classified as TLEC if lymphoplasmacytic infiltration is lacking. However, only about 50% of the cases are positive for EBV, which is lower compared to nasopharyngeal lymphoepithelioma. Instances of EBV infection in other types of thymic epithelial tumor have been reported at lower rates, which suggests that EBV infection may have an important influence on the carcinogenesis of TLEC, though the etiology is unknown. TLEC is a highly malignant tumor with poor prognosis, as affected patients have a median survival time of 22 months, according to 58 cases from the literature, while the 5-year survival rate is 34.4%. Presently, prognosis is not considered to be affected by the presence or absence of EBV positivity.

Common and rare carcinomas of the thymus

Thymic carcinoma encompasses a diverse group of rare tumors that occur almost exclusively in the prevascular (anterior) mediastinum. Thymic carcinomas have a worse outcome than thymomas with a median time to death of under 3 years. These tumors lack the typical lobulation of thymomas, exhibit commonly more cytologic atypia, are associated with a desmoplastic stromal reaction, and lack thymocytes, features that distinguish them from thymomas. The most common thymic carcinoma is squamous cell carcinoma; other subtypes include mucoepidermoid carcinoma, NUT carcinoma, and adenocarcinoma, among others. Largely due to multi-institutional and global efforts and meta-analysis of case reports and series, some of the thymic carcinoma subtypes have been studied in more detail and molecular studies have also been performed. Morphology and immunophenotype for the vast majority of thymic carcinoma subtypes are similar to their counterparts in other organs. Therefore, the distinction between thymic carcinoma and metastatic disease, which is relatively common in the prevascular mediastinum, can be challenging and in general requires clinical and radiologic correlation. Although surgical resection is the treatment of choice, only 46 to 68% of patients with thymic carcinoma can undergo resection as many other tumors present at high stage with infiltration into vital neighboring organs. These patients are usually treated with chemotherapy and/or radiation. The search for better biomarkers for prognosis and treatment of thymic carcinomas is important for improved management of these patients and possible targeted therapy.