Effect of open versus video-assisted thoracoscopy on perioperative outcomes and survival for cases of thymic carcinomas and thymic neuroendocrine tumors.

BACKGROUND: The oncology-related indices between open and video-assisted thoracoscopic surgery (VATS) procedures for thymic carcinomas (TCs) and thymic neuroendocrine tumors (TNETs) remain unclear. METHODS: Propensity score matching (PSM) and multivariate Cox proportional risk models were used to evaluate the perioperative outcomes and survival rates of patients undergoing open and VATS for TCs and TNETs at the Second Affiliated Hospital of Air Force Military Medical University Hospital, between 2009 and 2018. RESULTS: Of the total 126 cases of TCs and TNETs, VATS treatment was used in 39 (30.9%). Advanced age and Masaoka-Koga staging were found to be independent prognostic factors for both TCs and TNETs, through a multifactorial Cox regression analysis. There was no significant difference in survival between the VATS and open groups before and after PSM; however, the VATS group had better perioperative-related indicators. There were no significant differences between the groups in terms of mortality at 30 days, mortality at 90 days, R0 resection rate, and 5-year survival rate (67.5% vs. 58.5% [P = 0.260] in the VATS group compared to the open group, in a PSM analysis of the 27 VATS and 27 open groups). Compared to the open group, the VATS group had a shorter length of hospital stay (13 days vs. 16 days, P = 0.015), a shorter level I care (0 days vs. 1 day, P = 0.016), and less intraoperative bleeding (50 mL vs. 300 mL, P < 0.001). CONCLUSIONS: In this single-center retrospective study of TCs and TNETs, survival rates were comparable between the VATS group and the open group, and the VATS group showed improved perioperative-related parameters.

Thymic carcinomas and thymic neuroendocrine tumors: a tribute to Dr. Juan Rosai.

Throughout his career, Dr. Juan Rosai greatly impacted our understanding of mediastinal tumors, both as a scientist and as a teacher. This review highlights his manifold contributions in the field of thymic carcinomas and thymic neuroendocrine tumors from a historical perspective.

A Rare Case of Mediastinal Mass: Thymoma and Thymic Tumor.

Thymomas and thymic carcinomas are rare mediastinal neoplasms arising from thymic epithelial cells, and the presence of synchronous or metachronous primary thymic neoplasms in a single patient is an extremely rare event. Thymoma patients appear to have an inherent predisposition toward developing additional neoplasms. This additionally presents a diagnostic challenge, revealing the importance of multidisciplinary expertise to the management of these patients. This is a case report of a patient with a thymoma and thymic carcinoma, submitted to surgical resection and postoperative radiotherapy.

Molecular genetic characteristics of thymic epithelial tumors with distinct histological subtypes.

BACKGROUND: Due to the low incidence and histological heterogeneity, the molecular features and underlying carcinogenic mechanisms of thymic epithelial tumors (TETs) are yet to be fully elucidated, especially for different subtypes of TETs. METHODS: Tumor tissue samples of 43 TETs with distinct histological subtypes were collected. We analyzed the molecular characteristics in different subtypes based on whole exome sequencing data. RESULTS: The mutational profiles of the different subtypes of TETs varied. Compared with thymomas, thymic carcinomas (TCs) had a higher mutation frequency of MYO16 (33% vs. 3%, p = 0.024) and a lower frequency of ZNF729 mutations (0% vs. 35%, p = 0.044). No significant difference was observed in the median tumor mutation burden across different subtypes. The value of copy number variation burden, weighted genome instability index, and the number of amplified segments were all higher in TCs than thymomas, and they also tended to be higher in B3 thymoma than in non-B3 thymomas, while they had no significant differences between B3 thymoma and TCs. Clustering analyses revealed that Wnt, MAPK, Hedgehog, AMPK, and cell junction assembly signaling pathways were exclusively enriched in non-B3 thymomas, lysine degradation pathway in B3 thymoma, and extracellular matrix-receptor (ECM-receptor) interaction, positive regulation of cell cycle process, and activation of innate immune response pathways in TCs. CONCLUSIONS: This study revealed distinct molecular landscapes of different subtypes of TETs, suggesting diverse pathogenesis of non-B3 thymomas, B3 thymomas, and TCs. Our findings warrant further validation in future large-scale studies and may provide a theoretical basis for potential personalized therapeutic strategies.

A Single Center Analysis of Thymic Neuroendocrine Tumors.

PURPOSE: Thymic neuroendocrine tumors (TNETs) are a collection of slow-progressing neoplasms located in the anterior mediastinum. Relatively few previously published studies have focused on thymic carcinomas. This study investigated the basic clinical characteristics, treatment, and prognosis of TNETs. METHODS: Patients were enrolled in the study from January 2003 to December 2017 who had been diagnosed with TNETs through pathological screening and treated at our institution. Demographic data from each patient, the Masaoka stage, histology and size of the tumor, tumor invasion characteristics, and therapeutic strategies were gathered. The Kaplan-Meier method was used to assess patient survival. In addition, the log-rank test was used to carry out univariate analyses. RESULTS: Twenty-six patients were eligible for inclusion in the study. The median age of the patients was 46.5 (25-69) years. The tumor median maximum diameter was 7.9 cm (from 3 to 19 cm). Twenty-four patients were treated surgically. Nineteen patients completed radiation therapy, and sixteen patients underwent chemotherapy. A median follow-up time of 54.95 months was observed. The survival rate for three years was 75.0% and 70.6% for five years. The corresponding progression-free survival rates for three and five years were 55.7% and 37.7%, respectively. The local, regional recurrence-free survival (LRFS) rates were 87.2% and 81.7%, and the distant metastasis-free survival (DMFS) rates were 55.7% and 37.7%, at three and five years, respectively. Local recurrence (six patients) and bone metastasis (six patients) were observed as the most frequent failures. CONCLUSION: TNET was observed to be an aggressive but rare malignant lesion. While the predominant treatment was complete resection, chemotherapy and radiotherapy were also required due to the high recurrence rate.

Analysis of the tumor microenvironment and mutation burden identifies prognostic features in thymic epithelial tumors.

Thymic epithelial tumors (TETs) are one of the rarest adult malignancies in the anterior mediastinum. Thymic carcinomas (TCs) are less prevalent among TETs, but they are more clinically aggressive. Immunotherapy has emerged as a promising therapeutic approach for refractory TETs, even though chemotherapy remains the conventional treatment for the advanced disease. However, limited attention has been paid to the features of the tumor microenvironment (TME) which might provide clinically relevant information and guide treatment regimen design. Especially, to date, there have been only a few studies focusing on the differences between the TME and genomic features preserved by TETs and TCs. We analyzed the TME and genomic characteristics of TETs using RNA sequencing and whole-exome sequencing, finding that distinct characteristics of TME in different pathogenic subtypes of TETs. According to those findings, we found that thymic carcinomas had significantly lower expression of HMGB1, a pro-inflammatory cytokine-related gene, than thymomas, and low HMGB1 expression was linked to a poor prognosis. Additionally, higher mutation burdens were significantly associated with the later stage and more advanced pathological types. Thymoma patients with lower mutation burdens tended to relapse within 3 years. In summary, different characteristics of TME and genomic features between thymoma and thymic carcinoma were associated with clinical outcomes of TETs and presented promisingly predictive value for efficacy and toxicity of immunotherapy.

Investigational drugs for the treatment of thymic cancer: a focus on phase 1 and 2 clinical trials.

INTRODUCTION: Thymic epithelial tumors (TETs) are rare tumors of thymic epithelial cells. Treatment options for advanced disease patients who failed standard platinum-based chemotherapy are limited. AREAS COVERED: Phase I and II trials published in the last five years testing new systemic treatments for advanced TET patients are discussed, as well as ongoing trials. A PubMed database literature review was conducted for articles published between January 2016 and December 2021, and ongoing clinical trials were retrieved from ClinicalTrials.gov database. EXPERT OPINION: The most promising classes of new drugs in TET patients are angiogenesis inhibitors and immune checkpoint antibodies (ICIs). Sunitinib and Lenvatinib showed response rates of 26% and 38%, respectively, and ICIs showed durable responses in 20-25% in thymic carcinoma (TCs). Both approaches are mainly active in TCs, therefore new treatment options for thymomas are an unmet medical need.Two major new therapeutic strategies are ICI combinations with other drugs and drugs that target pathways that are dysregulated in TETs.Future challenges include the development of preclinical models to help identify novel targets and test new treatment strategies, and randomized clinical trials to provide reliable evidence based on survival endpoints.

Unusual Anterior Mediastinal Tumors Treated at a Tertiary Thoracic Center: A Case Series Analysis.

Several tumors arise from different structures within the mediastinum. Although each type of mediastinal tumor has a predilection for a specific compartment, the progression of growth from one compartment to another can occur. The anterior mediastinum is the site of several tumors that pose interesting diagnostic and therapeutic challenges to thoracic surgeons. The anterior mediastinum is the seat of the majority of neoplastic growths within the mediastinum. Thymomas and lymphomas are the most common pathologies of the anterior mediastinum. Tumors of mesenchymal origin (hemangioma, lymphangioma, lipomas) and their malignant counterparts may occur in any of the mediastinal compartments. Less common tumors of the anterior mediastinal compartment are ectopic thyroid and parathyroid tumors, germ cell tumors, mesenchymal origin tumors, hemangiomas, and cervicomediastinal hygromas. Most of the mediastinal growths usually remain clinically silent until they become large and cause compressive symptoms. Here, we present a case series of five anterior mediastinal tumors consisting of solitary benign teratoma, fibrous benign tumor, malignant fibrosarcoma, hamartomatous chondroma, and malignant thymoma.

Effect of Lymph Node Dissection on the Prognosis of Thymic Carcinomas and Thymic Neuroendocrine Tumors.

We aimed to analyze the effect of lymph node dissection (LND) and accurate lymph node (LN) status on the survival and prognosis of patients with thymic carcinomas (TCs) and thymic neuroendocrine tumors (TNETs) undergoing surgical treatment. The Surveillance, Epidemiology, and End Results database was queried for patients who underwent surgical resection for TCs and TNETs during 1998-2016. LN status were defined as no LND (LND-), pathologically negative with LND (N0), and LN metastasis positive (N+). We investigated outcomes of LN status together with other clinicopathological features for overall survival (OS). Subgroup analyses were performed between LND-, N0, and N+ cohorts using propensity score matching, to analyze the significance of LND in prognosis. A total of 812 patients were enrolled, including 623 with TCs and 189 with TNETs. The proportion of LN metastasis positive in TNETs was 58.8% which was significantly higher than that in TCs (30%) (P < 0.001). In multivariable Cox analysis of OS, patients with LND- had a significantly worse prognosis than those with N0 (P = 0.018); there was no difference between N+ and LND- (P = 0.560). After propensity score matching, patients with N0 still had better survival than those with LND- and N+ in subgroup univariable and multivariable analyses of OS; however, the survival of patients with LND- and N+ was not significantly different in multivariable analysis. It was demonstrated that LND in TCs and TNETs can clarify the status of LN metastasis, to more accurately evaluate patients' long-term prognosis.

Mutational landscape of thymic epithelial tumors in a Chinese population: insights into potential clinical implications.

BACKGROUND: Thymic epithelial tumors (TETs) are a heterogeneous group of rare malignancies which may be devastating, difficult to treat, and for which treatment options are limited. Herein, we investigated the comprehensive genomic alterations of TETs in a Chinese population for providing clinical management, especially targeted therapy. METHODS: Comprehensive genomic profiling (CGP) was performed with DNA targeted sequencing of cancer-associated genes (CSYS) from a cohort of 40 Chinese TET patients. TMB was measured by an in-house algorithm. MSI status was inferred based on the MANTIS (Microsatellite Analysis for Normal-Tumor InStability) score. The expression status of PD-L1 was estimated by immunohistochemistry. RESULTS: The mutational profiling of thymomas (Ts) and thymic neuroendocrine tumors (TNETs) showed scattered mutation distributions with no recurrently mutated genes. In contrast, thymic carcinomas (TCs) did show highly recurrent mutations including CDKN2A, CYLD, CDKN2B, and TP53. Among them, CDKN2A and CDKN2B mutations were the top potentially actionable alterations in TCs. PD-L1 expression was mainly present in Ts and TCs, and was predominant in males and smokers. CONCLUSIONS: Our study provided a comprehensive genetic alteration view on the largest Chinese cohort of TETs to date. The results identified different genomic mutational profiles of Ts, TCs, and TNETs, and analyzed potential druggable biomarkers with clinical implications in Chinese TET patients, which provided the evidence for precision medicine of rare TET patients.

Next-generation sequencing in thymic epithelial tumors uncovered novel genomic aberration sites and strong correlation between TMB and MSH6 single nucleotide variations.

Thymic epithelial tumors (TET) including thymomas and thymic carcinomas are rare, but they are common primary tumors in the anterior mediastinum. The etiology and tumorigenesis of TET remain unclear. To better understand the novel aberrations of this rare tumor and provide more significant mutation sites for targeted therapy, we performed next-generation sequencing detection on 55 patients with TET. Our results showed that most genes in 12 core pathways harbored aberrations of indeterminate potential. In 4 genes (ARID1A, KMT2C, TGFBR2 and MAP3K1), the indel frequency was above 90%. Dozens of genes, including TGFBR2, KMT2C, PRKDC, ATR, CHD2, SDHA, KDM5A, CHEK1, MSH6 and POLE, possessed frameshift indel with different frequencies in different hotspot sites, which could be the new targets of therapy for TET. For the first time, we revealed a strong correlation between the tumor mutational burden and single nucleotide variations, but not frameshift, on DNA mismatch repair gene MSH6 in TET.

Thymic Squamous Cell Carcinoma: A Population-Based Surveillance, Epidemiology, and End Result Analysis.

OBJECTIVES: Thymic squamous cell carcinoma (TSCC) is a rare neoplasm that has been sparsely cited in the literature. The aim of this study was to determine disease characteristics and prognostic factors of patients in a Surveillance, Epidemiology, and End Results (SEER) analysis. METHODS: Cases from 1990-2016 were retrieved from the SEER database and demographics, treatments, and survival outcomes were analyzed. RESULTS: The TSCC accounted for 72.4% of the thymic carcinomas and 7.2% of thymic tumors. The 276 patients (165 men) selected for analysis had a median age of 65 (24-85) years, and 201 patients were diagnosed with Masaoka-Koga stage III/IV. The median survival of TSCC was 59 months with a 49.0% 5-year OS rate, a better prognosis than lymphoepithelioma-like carcinoma (32.1%) and undifferentiated carcinoma (33.3%). Multivariate analysis revealed the Masaoka-Koga stage (p = 0.003) and surgical types (complete resection, incomplete resection, and none; p < 0.001) were determinants of survival. Complete resection had the best prognosis with a 72.7% 5-year OS rate. Chemotherapy was an independent protective factor (HR = 0.555, 95% CI 0.347-0.886; p = 0.014) though poor survival was showed in univariate analysis. And the survival benefit of chemotherapy was validated in PSM analysis (3-year OS rate was 77.7% with chemotherapy vs. 52.8% without chemotherapy; p = 0.014). CONCLUSIONS: TSCC was frequently diagnosed in older patients with advanced Masaoka-Koga stage and had more favorable survival than other subtypes of thymic carcinomas. Complete resection is the preferred treatment. Masaoka-Koga stage and chemotherapy had a strong association with prognosis.

Optimal management of thymic malignancies: current perspectives.

Thymic epithelial tumors (TETs) belong to orphan oncology. The incidence of TETs is about 1.3-3.2 cases per million worldwide. Following pathology, evolution and prognosis are variable. The World Health Organization classification distinguishes thymomas and thymic carcinomas. TETs are composed of thymic epithelial tumoral cells and normal lymphocytes. The mean age at diagnosis is 50-60 years-old. There are no identified risk factors. TETs are frequently associated with paraneoplastic syndromes as myasthenia gravis. The complete R0 surgical resection is the most significant prognosis factor on survival. In 2010, the French National Institute of Cancer labeled the RYTHMIC network as a specific tumor board including thoracic surgeons, oncologist, and radiation therapist to define standard of care for the management of TETs. The aim of the review was to update knowledge to optimize the standard of care.

Effect of clinicopathologic features on survival of patients with thymic carcinomas and thymic neuroendocrine tumors: A population-based analysis.

BACKGROUND: Thymic carcinomas (TCs) and thymic neuroendocrine tumors (TNETs) are aggressive cancers with poor survival outcome and limited investigation. This study is to investigate clinicopathologic features on TC and TNET patients' prognosis of a large cohort. MATERIALS AND METHODS: The Surveillance, Epidemiology, and End Results database were used to identify a total of 362 TC and TNET patients with documented clinicopathologic features we investigated. The characteristics and overall survival of the TC and TNET patients were studied. RESULTS: Two hundred and forty TC and 122 TNET patients were identified. For the entire cohort of TC and TNET, histologic type (P < 0.001), tumor size (P = 0.015), Masaoka-Koga stage (P = 0.008), regional node positive (P = 0.004), surgery of primary site (P < 0.001), lymph node surgery (P = 0.013), and chemotherapy (P = 0.001) were considered as significant clinicopathologic features that could affect prognosis of TC and TNET patients in univariate analysis. More importantly, histologic type (P < 0.001), regional nodes positive (P = 0.03) and surgery of primary site (P < 0.001) were able to independently predict overall survival of those patients. In addition, for the cohort of TC, we found that regional nodes positive (P = 0.034) and surgery of primary site (P = 0.001) could be independent predictors of TC patients' survival. CONCLUSION: Regional nodes detection is essential for TC and TNET patients. Surgery of primary site is the preferred primary treatment for those patients.

Association between Epstein-Barr virus and Thymic epithelial tumors: a systematic review.

The possible role of Epstein-Barr virus (EBV) in the pathogenesis of thymic epithelial tumors (TET) remains controversial. This study aimed to determine the prevalence of EBV in TET. We conducted a systematic review of relevant English-language studies published between January 1980 and December 2013. Effect size was calculated as event rates (95% confidence interval [CI]) by homogeneity testing using Cochran's Q and I2 statistics for benign TET, benign TET with myasthenia gravis (MG), and thymic carcinoma (TC). Among 136 potentially relevant studies, 22 met the inclusion criteria. Despite a considerable degree of heterogeneity, the pooled estimated incidences were 9% (95% CI, 1-23%), 20% (95% CI, 0-54%), and 6% (95% CI, 0-21%) for benign TET, benign TET with MG, and TC, respectively. There was significant heterogeneity among studies that used in situ hybridization (ISH) for both benign TET and benign TET with MG. According to the random-effects model, studies employing ISH yielded lower point estimates of EBV prevalence (5%) than those employing other methods (33%). Using the random-effects model, we found a lack of significant heterogeneity among studies from different geographic regions (p = 0.0848). Further, 12 of 23 lymphoepithelioma-like carcinoma (LELC) cases tested EBV-positive. The prevalence of EBV in benign TET with or without MG was lower than in nasopharyngeal carcinoma, suggesting that EBV plays a minor role in TET pathogenesis. Although the prevalence of EBV in TC was also low, EBV may play an important causal role in LELC. Further research is needed to clarify these associations.

Comparison of clinical features and survival between thymic carcinoma and thymic carcinoid patients.

OBJECTIVES: Thymic carcinoma (TC) and thymic carcinoid (TCD) are aggressive thymic epithelial neoplasms with a poor prognosis. Due to rarity, little is known about their comparative clinical characteristics, treatment outcomes and patterns of relapse. METHODS: A retrospective cohort study was performed on 287 patients with TC and 56 patients with TCD who were treated at the Shanghai Chest Hospital between February 2003 and April 2014. Patient demographics, tumour stage, treatment, pathologic findings and postoperative outcomes were compared between the two tumour types using both multivariable Cox regression analysis and propensity-matched analysis. RESULTS: Compared to patients with TC, significantly more patients with TCD were male, had larger tumours, and displayed a greater proportion of lymph node metastases. However, overall survival was similar (60.7% 5-year survival for TC, 80.7% for TCD, P = 0.159), as was disease-free survival (41.1% 5-year survival for TC, 37.6% for TCD, P = 0.696) and patterns of relapse. Multiple Cox regression analysis identified younger patients [hazard ratio (HR) 1.018; 95% confidence interval (CI) 1.000-1.035; P = 0.047], more completeness of resection (HR 1.424; 95% CI 1.105-1.836; P = 0.006), adjuvant radiotherapy (HR 0.455; 95% CI 0.276-0.751; P = 0.002), and no adjuvant chemotherapy (HR 1.799; 95% CI 1.017-3.183; P = 0.044) as independent factors predicting better overall survival. Completeness of resection (HR 1.258; 95% CI 1.022-1.548; P = 0.031) and TNM stage (HR 1.479; 95% CI 1.107-1.977; P = 0.008) were independent predictors of disease-free survival. Propensity matching produced 46 patients in each group and no significant difference on overall survival or disease-free survival was found. CONCLUSIONS: Patients with TCD have discrete features but share a similar clinical course to those with TC. The importance of complete resection in both of these thymic malignancies is emphasized. Further investigation at multiple centers with the longer follow-up data is required to substantiate our conclusion.

Cytoplasm estrogen receptor ß5 as an improved prognostic factor in thymoma and thymic carcinoma progression.

A number of previous studies have reported that sex steroid hormones, including estrogens, are involved in the regulation of the thymic function. The aim of the present study was to investigate the expression of estrogen receptor ß5 (ERß5) in thymic tumors and the correlation between ERß5 expression and thymoma biological characteristics. The expression levels of ERß5 in thymic epithelial tumors was evaluated in 103 patents using immunohistochemical staining and reverse transcription-quantitative polymerase chain reaction. In addition, an indirect immunofluorescence assay was performed to evaluate the ERß5 expression levels in the TC1889 and T1682 cell lines. The survival outcome was estimated using Kaplan-Meier plots. The results indicated that ERß5 expression was mainly located in the thymic tumor cell cytoplasm (87.37%; 90/103 cases) and overexpression was observed in thymic tumors compared with normal thymic tissues (P=0.001). Using the Kruskal-Wallis test, a statistically significant association was observed between cytoplasmic ERß5 (cERß5) expression and thymic tumor subtypes (P=0.024) and stages (P=0.003 and R=-0.376). The Kaplan-Meier plots revealed that cERß5 expression was significantly associated with improved overall and progression-free survival (P=0.008 and P=0.004, respectively). The present study suggested that overexpression of cERß5 may indicate an improved prognosis and may be involved in the underlying mechanism through which estrogen inhibits thymoma and thymic carcinoma development.

[Retrospective analysis of 50 thymic epithelial tumors in Rennes university hospital]. / Analyse rétrospective portant sur 50 tumeurs épithéliales thymiques au CHU de Rennes. Quelle concordance avec le référentiel RYTHMIC publié en 2010 ?

BACKGROUND: Thymic epithelial tumors (TET), including thymomas and thymic carcinomas, are rare and characterized by very different evolutionary patterns depending on histology and invasion stage. The therapeutic management is not well defined but is a subject of increasing interest. The descriptive and analytic objectives of this retrospective monocentric study were to analyze the clinical characteristics of patients with TET, and to assess the management of these tumors in our centre. METHODS: Adult patients with TET managed in the Rennes university hospital in the period 2000-2011 were selected via the pathology department. Their clinical and pathological features and survival were analyzed retrospectively. RESULTS: Fifty TET were retrieved (46 thymomas and 4 thymic carcinomas). Their clinical and histological features and their invasion stages were concordant with published studies. Their diagnostic and therapeutic managements were also in accordance with current guidelines. In univariate analysis, myasthenia and surgery were associated with better survival rates. CONCLUSION: Management of TET in Rennes university hospital is in accordance with guidelines.

A review of thymic tumors.

Thymic tumors represent 0.2-1.5 % of all malignancies with an incidence of 0.15 per 100,000 population. Thymic tumors are most common tumors of the anterior mediastinum accounting for 20 % of all mediastinal tumors and 50 % of all anterior mediastinal tumors. Over 90 % of all thymic tumors occur in anterior mediastinum, remainder occurring in neck or other mediastinal areas especially aortopulmonary window and retro cardiac area which are common sites for ectopic thymic tissues and possible explanation for failure in some cases of simple thymectomy to improve Myasthenia Gravis(MG). The aim of this review is to discuss histologic classification, diagnostic features, evaluation, management and prognosis of thymic tumors.