Prognosis of thymic epithelial tumors according to the new World Health Organization histologic classification

On the Histologic Classification of Thymoma

The classification of thymoma continues to be a source of controversy in pathology. The difficulties in histologic classification are evident from the number of proposals that have been offered over the years, as well as for the continuous changes and modifications introduced by the World Health Organization to their classification system over the past 20 years. We analyze here some of the issues involved in the classification of these tumors and the difficulties encountered for practicing pathologists in deciphering the "letters and numbers" system devised by the World Health Organization. We would like to propose an alternate approach to thymoma histologic classification that capitalizes on the basic observation of their cytologic features and incorporates the pattern of growth resulting from the interplay of the tumor cells with other cellular constituents as a secondary characteristic. The proposed histologic classification provides a simplified, reproducible means of histologically categorizing these tumors and can be easily understood by most practicing pathologists in simple and clear morphologic terms.

American Radium Society Appropriate Use Criteria for Radiation Therapy in the Multidisciplinary Management of Thymic Carcinoma

Importance

Thymic carcinoma is rare, and its oncologic management is controversial due to a paucity of prospective data. For this reason, multidisciplinary consensus guidelines are crucial to guide oncologic management.

Objective

To develop expert multidisciplinary consensus guidelines on the management of common presentations of thymic carcinoma.

Evidence Review

Case variants spanning the spectrum of stage I to IV thymic carcinoma were developed by the 15-member multidisciplinary American Radium Society (ARS) Thoracic Appropriate Use Criteria (AUC) expert panel to address management controversies. A comprehensive review of the English-language medical literature from 1980 to 2021 was performed to inform consensus guidelines. Variants and procedures were evaluated by the panel using modified Delphi methodology. Agreement/consensus was defined as less than or equal to 3 rating points from median. Consensus recommendations were then approved by the ARS Executive Committee and subject to public comment per established ARS procedures.

Findings

The ARS Thoracic AUC panel identified 89 relevant references and obtained consensus for all procedures evaluated for thymic carcinoma. Minimally invasive thymectomy was rated as usually inappropriate (regardless of stage) due to the infiltrative nature of thymic carcinomas. There was consensus that conventionally fractionated radiation (1.8-2 Gy daily) to a dose of 45 to 60 Gy adjuvantly and 60 to 66 Gy in the definitive setting is appropriate and that elective nodal irradiation is inappropriate. For radiation technique, the panel recommended use of intensity-modulated radiation therapy or proton therapy (rather than 3-dimensional conformal radiotherapy) to reduce radiation exposure to the heart and lungs.

Conclusions and Relevance

The ARS Thoracic AUC panel has developed multidisciplinary consensus guidelines for various presentations of thymic carcinoma, perhaps the most well referenced on the topic.

Prognostic CT features in patients with untreated thymic epithelial tumors

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.

Resection of Thymic Neuroendocrine Carcinoma Guided by Three-Dimensional Reconstruction: A Case Report

Primary thymic small cell neuroendocrine carcinoma (SCNEC), which possesses a more aggressive biological behaviour, including invasion of proximal structures, local recurrence, and distant metastasis, is extremely rare. According to a previous literature report, only a few patients with this disease have been reported, compared to patients with distant metastasis of bones, lungs, spleen, liver, and adrenal glands (1, 2). The report data suggest that SCNEC is a highly malignant tumour compared to most other tumours of the human body. In this study, we presented the case of a patient who underwent surgery guided by three-dimensional reconstruction modelling before the operation. We were fully prepared for the resection of this tumour using three-dimensional reconstruction modelling, even after reading the computed tomography (CT) images that showed a closed relationship with the pericardium, the vein of the right middle lung lobe, and the phrenic nerve. All these features demonstrate that SCNEC is highly malignant. To date, there are no procedural reports for three-dimensional reconstruction modelling in malignant thymus tumours.

"Radiotherapy for thymic epithelial tumors: What is the optimal dose? A systematic review."

Thymic epithelial tumors (TETs) are rare thoracic tumors, often requiring multimodal approaches. Surgery represents the first step of the treatment, possibly followed by adjuvant radiotherapy (RT) and, less frequently, chemotherapy. For unresectable tumors, a combination of chemotherapy and RT is often used. Currently, the optimal dose for patients undergoing radiation is not clearly defined. Current guidelines on RT are based on studies with a low level of evidence, where 2D RT was widely used. We aim to shed light on the optimal radiation dose for patients with TETs undergoing RT through a systematic review of the recent literature, including reports using modern RT techniques such as 3D-CRT, IMRT/VMAT, or proton-therapy. A comprehensive literature search of four databases was conducted following the PRISMA guidelines. Two investigators independently screened and reviewed the retrieved references. Reports with < 20 patients, 2D-RT use only, median follow-up time < 5 years, and reviews were excluded. Two studies fulfilled all the criteria and therefore were included. Loosening the follow-up time criteria to > 3 years, three additional studies could be evaluated. A total of 193 patients were analyzed, stratified for prognostic factors (histology, stage, and completeness of resection), and synthesized according to the synthesis without meta-analysis (SWIM) method. The paucity and heterogeneity of eligible studies led to controversial results. The optimal RT dose neither for postoperative, nor primary RT in the era of modern RT univocally emerged. Conversely, this overview can spark new evidence to define the optimal RT dose for each TETs category.

Does size affect the prognosis of resectable thymoma beyond the eighth edition TNM?

Background

Thymoma is a type of rare mediastinal tumor whose clinical characteristics and indicators of prognosis are poorly understood. This single‐institution retrospective study aimed to assess the predictive value of tumor, node, metastasis (TNM) staging incorporating tumor size in predicting the risk of thymoma recurrence after resection.

Methods

Four binary logistic regression models were developed. Models I and II included median tumor size and TNM stage, respectively. Model III included the above two variables. Model IV was model III containing these two variables and their interaction terms. All models were adjusted for WHO histological type, operational time, and adjuvant therapy.

Results

A total of 276 patients with a median age of 51.0, including 21 patients with thymoma recurrence, were included in this study. Models II or III showed a lower ‐2LogL and higher AUC (0.735 and 0.738 vs. 0.576) with significantly better discrimination than model I, and model III and model II shared similar discrimination. In model III, TNM stage was positively correlated with thymoma recurrence. The recurrence risk of patients with TNM stage IV was significantly higher than those with TNM stage I (OR of 11.03, p = 0.022). No significant correlation between the tumor size and recurrence risk (p = 0.779) and no interaction was found between medium tumor size and TNM stage in model IV.

Conclusions

This study suggests that the prediction contribution of the TNM stage combined with tumor size is similar to the TNM stage alone for tumor recurrence in patients with thymoma after surgical resection.

The effects of pharmacological interventions on smoking cessation in people with alcohol dependence: A systematic review and meta-analysis of nine randomized controlled trials

BACKGROUND

Pharmacotherapies are widely used for smoking cessation. However, their efficacy for people with alcohol dependence remains unclear.

OBJECTIVE

This study aimed to explore the effects of pharmacotherapies on smoking cessation for people with alcohol dependence.

METHODS

Five electronic databases were searched in January 2021 for randomized controlled trials (RCTs) reporting the use of pharmacotherapies to promote smoking cessation in people with alcohol dependence. The risk of bias was assessed using the Cochrane tool. RevMan version 5.3 was used to perform meta-analyses of the changes in smoking behaviour, and the Grades of Recommendation, Assessment, Development and Evaluation (GRADE) approach was used to assess the certainty of the evidence.

RESULTS

The search identified nine RCTs involving 908 smokers with alcohol dependence; eight were published in the USA and one in Canada. The risk of bias was low in three studies and unclear in the remaining six. The meta-analysis results showed that, compared with the placebo group, Varenicline had a significant effect on short-term smoking cessation (three RCTs, odds ratio [OR] = 6.27, 95% confidence interval [CI]: [2.49, 15.78], P < .05, very low certainty). Naltrexone had no significant effect on smoking cessation in short-term or long-term observations (three RCTs, OR = 0.99, 95% CI: [0.54, 1.81], P = .97, moderate certainty), and Topiramate had no significant effects (two RCTs, OR = 1.56, 95% CI: [0.67, 3.46], P > .05, low certainty). Only one trial reported that Bupropion did not affect smoking cessation.

CONCLUSION

Varenicline may promote smoking cessation in people with alcohol dependence. However, Naltrexone, Topiramate and Bupropion have no clear effect on increasing smoking abstinence among drinkers. The small number of studies and the low certainty of evidence indicate that the results should be interpreted cautiously.

Outcomes of thymoma after multimodal therapy and determinants of survival: A 16-year experience of a tertiary cancer center

Background

In this study, we aimed to evaluate the factors that contribute to survival outcomes in patients with thymoma treated with multimodal approaches.

Methods

A total of 203 patients (105 males, 98 females; median age: 49 years; range, 17 to 77 years) with Masaoka-Koga Stage II-IV thymoma between January 2002 and December 2018 were retrospectively analyzed. Data including diagnosis of myasthenia gravis, diagnosis of diabetes mellitus, disease stage, histological type of tumor, capsule invasion and surgical margin status, lymphadenectomy, adjuvant radiotherapy or chemotherapy, time from surgery to the first day of adjuvant treatment, length of hospital stay, and overall and disease-free survival rates were recorded.

Results

Of the patients, 91 had Stage II, 67 had Stage III, and 45 had Stage IV disease. A total of 123 patients (61%) had myasthenia gravis. Seventy-six patients received adjuvant radiotherapy and 48 patients received either neoadjuvant (n=35) or adjuvant (n=25) chemotherapy. Higher disease stage, presence of R1 resection, and treatment with chemotherapy were significant factors for decreased disease-free survival time. Older age, higher disease stage, longer postoperative hospital stay, chemotherapy, and disease recurrence were effective contributors to decreased overall survival time. Adjuvant radiotherapy had a statistically significant positive effect on overall survival only in patients with completely resected Stage IV disease (five-year overall survival: 94.7% vs. 79.1%, respectively; p=0.015). In the multivariate analysis, older age (hazard ratio: 4.26), higher disease stage (hazard ratio: 2.95), and longer hospitalization time (hazard ratio: 3.81) were significant prognostic factors for overall survival. Patients with local recurrence who underwent complete resection had a survival time comparable to non-recurrent patients (p=0.753).

Conclusion

For patients with thymoma, higher disease stage, age ≥50 years, longer hospitalization, and need for chemotherapy are associated with worse survival rates. Adjuvant chemotherapy has a positive impact on Stage IV disease. Resection of recurrent lesions has a valuable impact on survival.

Fibrous bands associated with higher Masaoka stage and poor recurrence-free survival in patients with thymoma

Background

Fibrous bands (FBs) are one of the histological features in tumors which can be confirmed by hematoxylin and eosin (H&E)‐stained slides. FBs have been reported to correlate with malignancy in various tumors. This study aimed to investigate whether the presence of FBs is associated with malignancy in thymoma.

Methods

A total of 123 consecutive patients with thymoma who underwent microscopically complete resections from January 2000 to December 2018 were enrolled into this study. H&E‐stained slides of all thymoma patients were re‐examined. Study patients were classified into two groups: with FBs (n = 36) and without FBs (n = 87). Clinicopathological characteristics, overall survival (OS), and recurrence‐free survival (RFS) were compared between the two groups. Furthermore, multivariate analyses were performed to identify whether the presence of FBs was associated with higher Masaoka stage and poor prognosis in patients with thymoma.

Results

The Masaoka stage was found to be higher and recurrence more likely in thymoma patients with FBs than in those without. RFS was significantly poorer in thymoma patients with FBs than in those without, although no significant difference was observed in OS between them. The presence of FBs was significantly associated with higher Masaoka stage in the multivariate analysis using logistic regression. Additionally, the presence of FBs was an independent prognostic factor for poor RFS in multivariate analysis using Cox's proportional hazards model.

Conclusions

The presence of FBs in patients with thymoma was associated with higher Masaoka stage, higher recurrence rate, and poorer RFS.

Key points

Significant findings of the study

Fibrous bands (FBs) are bands of fibrosis dividing tumors into different‐sized irregular islands. The presence of FBs is associated with higher Masaoka stage and poor recurrence‐free survival in patients with thymoma.

What this study adds

The presence of fibrous bands might be associated with the malignant behavior of thymoma. Confirming the presence or absence of FBs may result in personalized medication for patients with thymoma.

Interobserver variation in the classification of thymic lesions including biopsies and resection specimens in an international digital microscopy panel

Aims

Thymic tumours are rare in routine pathology practice. Although the World Health Organization (WHO) classification describes a number of well‐defined categories, the classification remains challenging. The aim of this study was to investigate the reproducibility of the WHO classification among a large group of international pathologists with expertise in thymic pathology and by using whole slide imaging to facilitate rapid diagnostic turnover.

Methods and results

Three hundred and five tumours, consisting of 90 biopsies and 215 resection specimens, were reviewed with a panel‐based virtual microscopy approach by a group of 13 pathologists with expertise in thymic tumours over a period of 6 years. The specimens were classified according to the WHO 2015 classification. The data were subjected to statistical analysis, and interobserver concordance (Fleiss kappa) was calculated. All cases were diagnosed within a time frame of 2 weeks. The overall level of agreement was substantial (κ = 0.6762), and differed slightly between resection specimens (κ = 0.7281) and biopsies (κ = 0.5955). When analysis was limited to thymomas only, and they were grouped according to the European Society for Medical Oncology Clinical Practice Guidelines into B2, B3 versus A, AB, B1 and B3 versus A, AB, B1, B2, the level of agreement decreased slightly (κ = 0.5506 and κ = 0.4929, respectively). Difficulties arose in distinguishing thymoma from thymic carcinoma. Within the thymoma subgroup, difficulties in distinction were seen within the B group.

Conclusions

Agreement in diagnosing thymic lesions is substantial when they are assessed by pathologists with experience of these rare tumours. Digital pathology decreases the turnaround time and facilitates access to what is essentially a multinational resource. This platform provides a template for dealing with rare tumours for which expertise is sparse.

Thymoma diagnosis and categorization in the current scenario: Morphological analysis based on interobserver variability

BACKGROUND:

Thymomas are not so common tumors that are encountered in day-to-day pathology reporting. The WHO system was proposed in 2015. Although, through its detailed reporting, the WHO elaborates all subtypes and morphological clinches to diagnosis, it was important to ascertain its reproducibility in our day-to-day reporting.

AIMS:

The aims of the study were (1) to study the interobserver agreement, concordance rates, and variability in the classification of a large number of thymomas received in our department as per the WHO 2015, (2) to correlate the WHO subtype with Masaoka–Koga stage, and (3) to study the variations in demography of thymomas in Indian patients as compared to those reported in the literature.

SETTING AND DESIGN:

This retrospective study was done at a tertiary care teaching hospital with huge surgical oncology patient load, also pertaining to the cardiothoracic surgeries. It is predominantly an interobserver agreement design to study the reproducibility of the WHO 2015 classification on thymic epithelial tumors.

METHODS:

Four pathologists have independently reviewed histopathology slides of 65 cases of thymomas and classified them into predefined categories. Kappa statistics was applied to the observations.

RESULTS:

There was a substantial interobserver agreement in overall classification of thymomas with a Cohen's kappa score of 0.66. A better score was achieved for the classification of Group B thymomas. The WHO subtypes correlate well with the Masaoka–Koga staging system, and this finding is statistically significant. This article also presents the clinical details of a large number of thymoma cases.

CONCLUSION:

The new WHO classification has good reproducibility among pathologists in thymoma reporting.

Impact of Definitive Radiotherapy and Surgical Debulking on Treatment Outcome and Prognosis for Locally Advanced Masaoka-Koga stage III Thymoma

The role of definitive radiotherapy (dRT) and debulking surgery (DS) for patients with locally advanced, unresectable, Masaoka-Koga stage III thymomas was not well studied. Unresectable tumor refers to tumor that could not be completely resected because of invasion of surrounding organs. Consecutive patients with unresectable stage III thymomas between 2000 and 2017 were reviewed. According to the treatment intent and radiation dose, patients were categorized into a dRT group and a non-dRT group. The former group included patients who received radiotherapy at doses ≥ 54 Gy after DS or biopsy. The latter group included patients who did not receive radiotherapy and those who received a radiation dose < 54 Gy. A total of 82 patients were included. Compared with non-dRT, dRT significantly improved 5-year overall survival (OS, P = 0.003), progression-free survival (PFS, P = 0.008), and freedom from locoregional failure (FFLF, P < 0.001). Compared with biopsy alone, DS did not improve OS, PFS, FFLF. On multivariate analysis, dRT was an independent prognostic factor for OS (hazard ratio [HR]: 2.37, P = 0.024), PFS (HR: 2.40, P = 0.004), and FFLF (HR: 3.83, P = 0.001). In conclusion, dRT was an effective and beneficial treatment for patients with unresectable Masaoka-Koga stage III thymoma.

Clinical prognostic scores for patients with thymic epithelial tumors

Several inflammation-based prognostic scores emerged in various types of cancer to predict clinical outcomes. So far, no accurate pre-treatment scoring systems exist for patients with thymic epithelial tumors (TETs), comprising thymomas and thymic carcinomas (TCs). Therefore, we sought to test the prognostic value of different clinical composite scores and their components, identify optimal cut-off values for TETs as well as combine predictive components to new suitable prognostic scores. One hundred eighty-four patients with TETs undergoing surgical tumor resection were analyzed. A significant advantage in Freedom-from-Recurrence and/or Cause-specific survival (CSS) was evident for patients with high Advanced-Lung- Cancer-Inflammation-Index, low CRP-Fibrinogen-Score (CFS), low Glasgow-Prognostic-Score (GPS), low high-sensitivity-modified GPS, low TET-adapted GPS (TET-aGPS) and low Systemic-Immune-Inflammation Index. On multivariable analysis high TET-aGPS (HR = 14.9;p = 0.001), incomplete resection status (HR = 13.5;p = 0.001) and TC (HR = 26.0;p = 0.001) were significant independent prognostic factors for worse CSS. The CFS had the highest coefficient of determination (R² = 0.188) to predict tumor recurrence of all composite scores, comprising CRP (R² = 0.141) and fibrinogen (R² = 0.158), the best single factor predictors. Inflammation-based prognostic scores and selected components are suitable to predict survival and/or tumor recurrence in TET patients undergoing primary surgery. Due to excellent long-term survival and frequent tumor recurrence, cut-off values were tailored to increase prognostic power.

Eukaryotic Translation Initiation Factor 3b is both a Promising Prognostic Biomarker and a Potential Therapeutic Target for Patients with Clear Cell Renal Cell Carcinoma

Eukaryotic translation initiation factors (eIFs) constitute a new class of therapeutic cancer targets. EIF3b is the major scaffold protein of eIF3 (the largest core of eIFs). We sought to define the role played by and the mechanism of action of eIF3b in patients with clear cell renal cell carcinoma (ccRCC). We found that high-level eIF3b expression in tumors was not only associated with an aggressive tumor phenotype, but was also independently prognostic for patients with ccRCC. Knockdown of eIF3b impaired the action of the Akt pathway, thus inhibiting cell proliferation by disrupting the cell cycle and triggering apoptosis. Furthermore, the epithelial-to-mesenchymal transition was impaired after eIF3b depletion, via suppression of cell migration and invasion. Additionally, eIF3b knockdown significantly inhibited the growth of subcutaneous xenografts in mice. Together, these data show that eIF3b is both a promising prognostic biomarker and a potential therapeutic target for patients with ccRCC.

[Pretreatment Biopsy for Histological Diagnosis and Induction Therapy in Thymic Tumors]

背景与目的

探讨术前病理学诊断在胸腺肿瘤诊断和治疗中的价值及其对胸腺肿瘤治疗的影响。

方法

对中国胸腺肿瘤协作组（Chinese Alliance for Research in Thymomas, ChART）收集的1994年-2012年的多中心且具有明确活检状态的胸腺肿瘤患者的临床病理资料进行回顾性分析，探讨术前病理学诊断的应用趋势及其对胸腺肿瘤患者预后的影响。

结果

1, 902例胸腺肿瘤患者中，术前病理学诊断患者336例（17.1%）。近年来术前病理学诊断的比例较前明显增加（P=0.008），胸腔镜/纵隔镜/超声内镜下经支气管活检（endobronchial ultrasound, E-BUS）比例较前升高（P=0.029）。术前行病理学诊断患者的生存明显差于无病理学诊断患者（P < 0.001），术前病理学诊断后的目的与肿瘤的Masaoka分期（P < 0.001）、切除程度（P=0.025）、病理类型（P < 0.001）具有相关性。术前病理学诊断后直接手术患者的生存要明显优于诱导治疗后再手术患者（P < 0.001）。

结论

胸腺瘤诊断主要依靠临床及组织学判断，近年来术前病理学诊断在胸腺肿瘤的诊断和治疗中起重要作用；根治性手术切除是胸腺肿瘤的首先治疗手段；术前病理学诊断后直接手术患者的预后要明显优于诱导治疗后患者。

Patterns of metastasis and recurrence in thymic epithelial tumours: longitudinal imaging review in correlation with histological subtypes

AIM

To determine the patterns of metastasis and recurrence in thymic epithelial tumours based on longitudinal imaging studies, and to correlate the patterns with World Health Organization (WHO) histological classifications.

MATERIALS AND METHODS

Seventy-seven patients with histopathologically confirmed thymomas (n=62) and thymic carcinomas (n=15) who were followed with cross-sectional follow-up imaging after surgery were retrospectively studied. All cross-sectional imaging studies during the disease course were reviewed to identify metastasis or recurrence. The sites of involvement and the time of involvement measured from surgery were recorded.

RESULTS

Metastasis or recurrence was noted in 24 (31%) of the 77 patients. Patients with metastasis or recurrence were significantly younger than those without (median age: 46 versus 60, respectively; p=0.0005), and more commonly had thymic carcinomas than thymomas (p=0.002). The most common site of involvement was the pleura (17/24), followed by the lung (9/24), and thoracic nodes (9/24). Abdominopelvic involvement was noted in 12 patients, most frequently in the liver (n=8). Lung metastasis was more common in thymic carcinomas than thymomas (p=0.0005). Time from surgery to the development of metastasis or recurrence was shortest in thymic carcinoma, followed by high-risk thymomas, and was longest in low-risk thymoma (median time in months: 25.1, 68.8, and not reached, respectively; p=0.0015).

CONCLUSIONS

The patterns of metastasis and recurrence of thymic epithelial tumours differ significantly across histological subgroups, with thymic carcinomas more commonly having metastasis with shorter length of time after surgery. The knowledge of different patterns of tumour spread may contribute to further understanding of the biological and clinical behaviours of these tumours.

Prognostic stratification of thymic epithelial tumors based on both Masaoka-Koga stage and WHO classification systems

BACKGROUND

The aims of this study were to stratify the risk of recurrence based on the Masaoka-Koga stage and World Health Organization (WHO) classification systems after R0-resection for thymic epithelial tumors (TETs).

METHODS

A retrospective analysis was conducted on 479 patients who underwent surgery between Jan 1994 and Feb 2014 for TETs. The study group comprised 251 males and 228 females, with a median age of 52 years (range, 15-84 years).

RESULTS

Of the 479 patients, 406 (84.8%) patients underwent R0-resection. Recurrence after R0-resection occurred in 32 patients during a median follow-up of 53 months (range, 2-227 months). A multivariate analysis revealed that the preoperative treatment including chemotherapy (P=0.036), Masaoka-Koga stage (P=0.011) and the WHO classification (P=0.001) were predictors for recurrence after R0-resection. Patients were stratified into four risk groups using a potential model incorporating both the Masaoka-Koga stage and WHO classifications. Group 1 comprised WHO types A/AB/B1 in stage I/II; Group 2 comprised WHO type A/AB/B1 in stage III or WHO type B2/B3 in stage I/II or WHO type C in stage I; Group 3 comprised Type B2/B3/C in stage III, or WHO type C in stage II/III; and Group 4 comprised WHO type B2/B3/C in stage IV. The 5-year freedom-from-recurrence (FFR) rates were 99.4% for group 1, 84.7% for group 2, 63.7% for group 3, and less than 44.4% for group 4 (P<0.001). In group 3, the rate of locoregional recurrence of patients treated with postoperative radiation therapy was lower than patients treated without postoperative radiation therapy (P=0.032).

CONCLUSIONS

A risk model incorporating both Masaoka-Koga stage and WHO classification systems may provide multi-faceted information about recurrence and adjuvant treatment after R0-resection of TETs.

Clinicopathological analysis of 241 thymic epithelial tumors-experience in the Shanghai Chest Hospital from 1997-2004

BACKGROUND

To assess the correlation of WHO histological classification of thymomas and thymic carcinomas (TCs) with prognosis in recently treated patient cohort compared to a historical one from a single institution.

METHODS

Retrospective review of clinical charts and histological sections of 241 patients treated during 1997-2004. Univariate and multivariate analysis of associations between risk factors including gender, age, tumor size, myasthenia gravis, WHO histological subtype, Masaoka stage, resection status, (neo-)adjuvant therapies, and survival.

RESULTS

The 5-year overall survival (OS) of A, AB, B1, B2, B3 thymomas and TCs patients was 100%, 100%, 94%, 80%, 94% and 45%. Five-year progression-free survival (PFS) was 100%, 96%, 78%, 80%, 78% and 39%, respectively. The 5-year OS of patients with Masaoka stage I, II, III and IV thymomas and TCs was 96%, 89%, 59% and 50%. (Neo-)adjuvant therapies were administered more often than in the historical cohort. Tumor-related death mainly occurred in patients with stage III, IV and B2, B3 thymomas and TCs. By univariate analysis, gender, tumor size, myasthenia gravis (MG) status, histotype, Masaoka stage, resection status and treatment were associated with OS. By multivariate analysis, histological subtype, Masaoka stage, and (neo-)adjuvant therapy were revealed as independent prognostic indicators.

CONCLUSIONS

WHO histological subtype, Masaoka stage and (neo-)adjuvant treatment have remained independent determinants of OS in patients with thymomas and TCs. Compared with the historical cohort during 1969-1996, prognosis of patients with B2, B3 thymomas has improved, which may be partly due to the increased use of adjuvant therapies. Prognosis of patients with TCs remained unsatisfactory, suggesting that neoadjuvant treatment should be tested to improve survival.

The impact of thymoma histotype on prognosis in a worldwide database

INTRODUCTION

The rarity of thymomas and lack of multi-institutional studies have hampered therapeutic progress for decades. To overcome this, the members of the International Thymic Malignancy Interest Group created a worldwide retrospective database. This database was analyzed regarding the demographic and geographic distribution of thymomas and the impact of different variables on survival and recurrence.

METHODS

This study analyzed 4221 thymomas diagnosed between 1983 and 2012 with World Health Organization histotype information from the International Thymic Malignancy Interest Group database. Associations to survival and recurrence were studied by univariate and multivariate analyses.

RESULTS

Type B2 thymoma is the most common (28%) and type A the least common (12%) histotypes. They are significantly more frequent in Europe and the United States than Asia. Type A and AB occur at significantly higher age than other thymomas (64 and 57 years, respectively). There are no differences in gender distribution. Stage is lower in type A (90% in stages I-II) and AB than B1 to B3 thymomas (38% of type B3 in stage III). In univariate analysis, recurrence is significantly less frequent among stage I/II tumors, in type A and AB (recurrence rates, 1-2%) than B1 to B3 thymomas (2-7%). Multivariate analysis reveals an impact of age, stage, and resection status on survival and recurrence, whereas for histology there is only a significant impact on recurrence.

CONCLUSION

New findings are (1) geographic differences such as a lower incidence of type A and B2 thymoma in Asia; and (2) impact of stage and histology, the latter partially limited to early stage disease, on recurrence.

Reproducibility of the WHO classification of thymomas: practical implications

BACKGROUND

The WHO-classification was shown to be an independent prognostic marker in some but not all retrospective studies possibly due to lack of reproducibility. We investigated the reproducibility of the WHO-classification and its prognostic implication using a large series of resected thymomas.

METHODS

Four independent pathologists histologically classified a surgical series of 129 thymic tumors in a blinded fashion. Fleiss' kappa-coefficient was used to assess the pathologists' overall agreement, and Cohen-Kappa to assess the agreement between two observers. Disease-related-survival (DRS) and progression-free-survival (PFS) curves were generated by Kaplan-Meier method and compared by log-rank test.

RESULTS

In 63/129 (48.8%) cases there was a complete agreement; in 43/129 (33.3%) cases 3/4 pathological diagnoses were identical; in 15/129 (11.6%) cases the diagnoses were identical by pair; in 8/129 (6.2%) cases three different pathological diagnoses were on record. The Kappa-correlation coefficient was only moderate (0.53). A following web review carried out on the 23 cases with at least two different diagnoses reached a complete consensus. The histotype showed a statistically significant impact on PFS and DRS in the classification provided by only two pathologists.

CONCLUSIONS

In this study, the agreement on WHO classification of thymomas was only moderate and this impacted on patients management. Web consensus conference on the diagnosis, more stringent diagnostic criteria or the adoption of referral diagnostic centres may substantially reduce discrepancies.

Expression of c-Jun, p73, Casp9, and N-ras in thymic epithelial tumors: relationship with the current WHO classification systems

Background

To evaluate the expression and differential significance of c-Jun, p73, Casp-9 and N-ras in thymic epithelial tumors (TETs) with the aim to provide useful information for tumor biology and prospective therapy.

Methods

In this study, we analyzed the expression of four chromosome 1-related genes, namely c-Jun, p73, Casp-9 and N-ras, in 60 cases of thymic epithelial tumors. The tumors included 52 thymomas and 8 thymic carcinomas which were categorized according to the current WHO classification systems.

Results

Compared with the normal thymus tissue, all thymic epithelial tumors demonstrated higher expression of c-Jun and p73. The expression of c-Jun and p73 in type B2, B3 thymoma and thymic carcinomas was similar, and significantly higher than that in all other subtypes of thymomas. Unlike type A thymoma, the expression of Casp-9 was relatively lower in type B thymoma and thymic carcinomas. With respect to the clinical staging systems, c-Jun was more expressed in progressive tumors harboring higher stages. In contrast to c-Jun, p73 and Casp-9, there was no significant aberration with N-ras expression irrespective of either tissue or tumor types.

Conclusions

The overexpression of c-Jun, p73 and Casp-9 in thymic epithelial tumors is closely related with the pathogenesis and biological behavior of the neoplasms. These candidate biomarkers provided useful information for prospective personalized therapy in the clinical management.

Additional non-English language abstract language: Chinese

背景:评估c-Jun, p73, Casp-9 和 N-ras在胸腺上皮性肿瘤诊断和鉴别诊断中的运用.

方法:根据世界卫生组织最新的诊断标准60例胸腺上皮性肿瘤分类,运用Envision法检测c-Jun,p73,Casp-9 和N-ras在不同亚型肿瘤中的表达情况,并结合临床病理学特征进行分析.

结果:c-Jun和p73在肿瘤中的表达明显高于正常胸腺组织;c-Jun和p73在B3,B2型胸腺瘤和胸腺癌的表达类似,且表达明显高于其他类型的胸腺肿瘤;Caspase-9在B型胸腺瘤和胸腺癌中的表达相对低于A型胸腺瘤;c-Jun的表达更常见于高级别的胸腺肿瘤.

结论:c-Jun,p73和Casp-9在胸腺肿瘤中的表达很好地反映了肿瘤的生物学特点,为胸腺肿瘤的诊断和鉴别诊断提供了较好的理论基础.

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En bloc extended total thymectomy and extrapleural pneumonectomy in Masaoka stage IVA thymomas

BACKGROUND

Surgical excision is the primary treatment for a thymoma. However, for advanced thymoma that extends to within the thoracic cavity and for recurrent cases with pleural dissemination (Masaoka stage IVA), the appropriate treatment is controversial. We evaluated the safety of surgery and outcomes of seven patients that underwent an en bloc extended total thymectomy and extrapleural pneumonectomy for stage IVA thymomas.

METHODS

From 1994 to 2009, five patients initially diagnosed with pleural dissemination and two patients with recurrent tumors in the pleura and lungs after a total thymectomy, were identified. Seven patients had an extrapleural pneumonectomy performed. For the first operation, five patients underwent additional en bloc extended total thymectomy.

RESULTS

Two recurrent cases were identified 55.2 and 12.3 months after first operation. Two patients had WHO type B1-B2 tumors, two had B2, two had B2-B3, and one had a B3 tumor. The mean hospital stay was 15.3 days (range: 7-29). There was no operative mortality. Four patients had neoadjuvant chemotherapy and five were treated with adjuvant chemotherapy. The median survival was 30.6 months and the Kaplan-Meier 2-year survival was 100% (95% confidence interval: 24.6-36.6 months). One patient, who did not receive induction chemotherapy, had distant metastases after surgery.

CONCLUSIONS

En bloc extended total thymectomy and extrapleural pneumonectomy can be safely performed on selected patients with stage IVA thymomas and is expected to achieve complete local control. Although the treatment strategy has yet to be standardized, complete resection with appropriate systemic therapy may improve survival in otherwise fatal disease.

Management of stage I and II thymoma

With a knowledgeable assessment of the clinical presentation and demographic and radiologic characteristics, most thymomas can be reliably identified preoperatively without the need for a biopsy. Surgery is the mainstay of treatment for stage I and II thymoma. The rate of complete resection is essentially 100% by open techniques, and recurrences are rare. A complete thymectomy via a sternotomy is the standard approach. Adjuvant radiotherapy after a complete resection does not appear to be of benefit. In the rare event of a recurrence, an aggressive approach should be taken with re-resection whenever possible.

Prediction of thymoma histology and stage by radiographic criteria

Thymic epithelial tumors, such as thymomas and thymic carcinomas, are the most common primary neoplasms of the mediastinum. In 1999, the World Health Organization (WHO) proposed a consensus classification of thymic epithelial tumors based on the morphology of the epithelial cells and the ratio of lymphocytes to epithelial cells, which was revised in 2004. The latest classification system stratifies thymic epithelial tumors into six categories: types A, AB, B1, B2, B3, and thymic carcinoma. This article describes the prediction of thymoma histology and stage on the basis of radiographic criteria by reviewing the following: the WHO histologic classification of thymic epithelial tumors, the clinical staging of thymomas based on prognosis, and the radiographic appearance of thymomas according to the WHO histologic classification.

Staging system of thymoma

INTRODUCTION

Thirty years have gone by since the Masaoka staging system of thymoma was proposed in 1981. Although the Masaoka staging system has been accepted by many surgeons and pathologists, some proposals of revision and improvements have been suggested. At this time, I reinvestigated the Masaoka staging system based on the recent follow-up study of the thymomas resected at Nagoya City University.

METHODS

Using the follow-up results of 211 thymomas in Nagoya, I analyzed the following aspects: (1) evaluation of the Masaoka staging system as a prognostic factor in the Nagoya series and (2) critical assessment of the proposals of revision to the Masaoka staging system.

RESULTS

(1) Univariate analysis showed that Masaoka stages were significantly prognostic for overall survival (p < 0.0001). (2) The difference of survivals between stage I and II was not significant, but progression-free survival of stage I was 100% for up to 20 years, whereas one tumor death case in stage II was found. (3) Differences of survival between the cases with and without great vessel invasion in stage III were not significant. (4) Prognosis of N tumors was yet better defined.

CONCLUSION

(1) The Masaoka staging system remains a valuable prognostic factor. (2) Combination of stage I with II and separation of stage III into subgroups are not recommended. (3) At the moment, it is better to include N tumors in stage IVb.

WHO types A and AB thymomas: not always benign

The 2004 WHO classification of thymic tumors recognizes five major subtypes of thymomas and thymic carcinoma. Subtypes A and AB thymomas are purported to be benign neoplasms, although prior studies have suggested a potential for malignant behavior. The purpose of this study was to assess the clinical behavior of A and AB thymomas identified from a large institutional pathologic database. A retrospective slide review of 500 thymic epithelial tumors identified 71 (∼ 14%) cases of types A and AB thymomas. Clinical history and follow-up information were obtained through retrospective chart review. There were 38 and 33 cases of types A and AB thymomas, respectively. Complete follow-up data were available in 37 (52%) cases. Eighteen (49%) patients (type A, n=9 and type AB, n=9) had evidence of recurrent/metastatic disease at an average of 62 months (range from 6 to 244 months) after initial diagnosis. Survival curves for patients with types A and AB thymomas, with and without recurrences, show a statistically significant difference (P=0.001 and 0.005, respectively). Analysis of this large cohort confirms the potential for subtypes A and AB thymomas to show malignant behavior. Long-term clinical monitoring, therefore, appears to be justified in these cases. This study also shows the poor correlation between the WHO classification and tumor behavior.

World Health Organization classification of thymomas provides significant prognostic information for selected stage III patients: evidence from an international thymoma study group

Information regarding prognosis of thymoma patients stratified by both World Health Organization classification and Masaoka staging system is very limited. Analyze 5-year survival data from a large number of thymoma patients stratified by both World Health Organization histologic type and Masaoka stage using meta-analysis. Perform power analysis to estimate the number of cases that would be needed to test the null hypothesis to a power of 80%. Five-year survival data from 905 thymoma patients treated with thymectomy at seven hospitals in America, Japan, Korea, India, Italy, and Germany. Survival data was reported as "dead" or "alive" to facilitate meta-analysis. Significant differences were detected only when comparing survival rates of thymoma patients in stages I to III with those of stage IV disease. Analysis by World Health Organization histologic type and stage yielded significant differences only in patients with thymomas A vs. B2 and A vs. B3 in stage III disease. No significant data heterogeneity was detected with funnel plots and Egger's regression test. Power analysis estimated that a study with 7077 patients is needed to evaluate the prognostic significance of all thymomas stratified by both World Health Organization histologic type and stage to a power of 80%. Selected World Health Organization histologic types are significantly associated with prognosis in stage III thymoma patients and may help select individuals benefiting from neoadjuvant therapy. Power analysis shows that studies with much larger number of patients are needed to exclude the possibility that histologic type may provide significant prognostic information in other stages of the disease.

Thymoma: Results of treatment and role of radiotherapy

PURPOSE

The aim of this study is to assess results of treatment, factors influencing prognosis with regard to causes of failure and treatment tolerance in patients with thymoma.

MATERIAL AND METHODS

Between 1966 and 2006, 63 patients with thymoma had been treated at the Centre of Oncology in Krakow. Patients were treated by means of different treatment modalities: surgery followed by radiotherapy (52%), radiotherapy alone (13%), chemoradiotherapy alone (15%), surgery followed by chemoradiotherapy (5%), surgery alone (5%) and others.

RESULTS

The 10-year locoregional recurrence-free survival (LRRFS) was 79%, disease free survival (DFS) was 57% and overall survival (OS) was 57%. Masaoka stage was the only independent prognostic factor for LRRFS. Masaoka stage and method of radiotherapy delivery (higher photon energies), were independent prognostic factors for OS. For DFS, the independent prognostic factors were age, type of treatment (favoured surgery followed by radiotherapy or chemoradiotherapy), Masaoka stage and year of start of treatment. Most common reactions were lung fibrosis in 36% of patients (mainly asymptomatic in most patients), pneumonitis (9%) and oesophagitis (4%).

CONCLUSIONS

Surgery combined with radiotherapy and chemoradiotherapy and modern radiotherapy techniques are correlated with improvement of survival in patients with early stage thymoma.

Association between thymoma and persistent hypothermia: a case report

INTRODUCTION

Thymomas are rare, slow-growing tumours that present in a variety of ways such as incidental findings on chest radiographs following symptoms of cough and dyspnoea. Thymomas may also present with symptoms due to intrathoracic spread such as superior vena cava obstruction, or with symptoms of an associated paraneoplastic disorder. Such paraneoplastic disorders are typified by the generation of autoantibodies directed against a variety of self antigens including myasthenia gravis, neuromyotonia, and hypogammaglobulinaemia. Significant hypothermia in association with thymoma has been described previously in one published case report. The basis for hypothermia in that case was not clear, but was postulated to relate to abnormal central thermal regulation and was resolved completely following treatment with intravenous gammablobulin, thus suggesting an autoimmune aetiology.

CASE PRESENTATION

We present the case of an 88-year-old man with Type A thymoma and persistent hypothermia. An extensive investigation of the hypothermia revealed no aetiology other than the thymoma itself. Symptoms of hypothermia were treated effectively with passive and active external rewarming. The patient's dyspnoea was much improved by intercostal drainage of a left-sided pleural effusion and talc pleurodesis. He was not offered definitive treatment for the thymoma in view of its relatively favourable prognosis, and because his symptoms were well controlled at the time of discharge.

CONCLUSION

We suggest that the possibility of thymoma be investigated once the more common causes of hypothermia have been excluded in an appropriate clinical context. To the best of our knowledge, this is only the second published case report describing such an association.

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

This study retrospectively reviewed the clinicopathological features of thymic epithelial tumors in 108 patients, and evaluated World Health Organization (WHO) histologic classification of thymic tumors. Other prognostic factors, including age, gender, clinical stage, and completeness of tumor resection were also analyzed. Seven type A tumors, 19 type AB, 23 type B1, 19 type B2, 27 type B3, and 13 thymic carcinomas were studied. The 5-year and 10-year survival rates were 100% after resection of tumor types A and AB; 93% and 81% for B1; 83% and 70% for B2; and 43% and 33% for B3. The overall 5-year and 10-year survival rates were 72.0% and 63.0%, respectively. Tumor classification was highly significant in predicting survival ( P .001) and also reflected the clinical behavior of tumors. The Masaoka stage was the most important independent prognostic index in thymomas. The WHO histologic subtype and completeness of resection were also important prognostic factors.

Postoperative radiotherapy after surgical resection of thymoma: differing roles in localized and regional disease

PURPOSE

To analyze the Surveillance, Epidemiology and End Results (SEER) registry data to determine the impact of postoperative radiotherapy (PORT) for thymoma and thymic carcinoma (T/TC).

METHODS AND MATERIALS

Patients with surgically resected localized (LOC) or regional (REG) malignant T/TC with or without PORT were analyzed for overall survival (OS) and cause-specific survival (CSS) by querying the SEER database from 1973-2005. Patients dying within the first 3 months after surgery were excluded. Kaplan-Meier and multivariate analyses with Cox proportional hazards were performed.

RESULTS

A total of 901 T/TC patients were identified (275 with LOC disease and 626 with REG disease). For all patients with LOC disease, PORT had no benefit and may adversely impact the 5-year CSS rate (91% vs. 98%, p = 0.03). For patients with REG disease, the 5-year OS rate was significantly improved by adding PORT (76% vs. 66% for surgery alone, p = 0.01), but the 5-year CSS rate was no better (91% vs. 86%, p = 0.12). No benefit was noted for PORT in REG disease after extirpative surgery (defined as radical or total thymectomy). On multivariate OS and CSS analysis, stage and age were independently correlated with survival. For multivariate CSS analysis, the outcome of PORT is significantly better for REG disease than for LOC disease (hazard ratio, 0.167; p = 0.001).

CONCLUSIONS

Our results from SEER show that PORT for T/TC had no advantage in patients with LOC disease (Masaoka Stage I), but a possible OS benefit of PORT in patients with REG disease (Masaoka Stage II-III) was found, especially after non-extirpative surgery. The role of PORT in T/TC needs further evaluation.

Evidence-Based Pathology and the Pathologic Evaluation of Thymomas: Transcapsular Invasion Is Not a Significant Prognostic Feature

Context.—Evaluation of transcapsular invasion is currently considered very important in the pathologic examination of thymomas. However, recent studies have questioned the prognostic value of stratifying thymoma patients into stage I and II disease. Evidence-based pathology promotes the use of systematic reviews of literature and meta-analysis of data to synthesize the results of multiple publications.

Objective.—To analyze the data in the literature regarding the prognostic importance of transcapsular invasion in thymoma stage I and II.

Design.—A systematic review of the English literature was carried out for “thymoma,” “stage,” and “prognoses.” Case reports, case series with fewer than 10 cases, and studies with follow-up periods shorter than 5 years were excluded. Twenty-one retrospective publications reporting the experience with 2451 thymomas were selected for review, including 1419 stage I and 1032 stage II patients. Meta-analysis was performed, and possible publication bias was studied with funnel plots of precision and various statistics.

Results.—Meta-analysis yielded no significant differences in disease-free or overall survival rates in stage I and II thymoma patients. Funnel plots of precision and statistical tests such as the Egger regression intercept test showed no significant publication bias.

Conclusions.—The lack of significant differences in the prognosis of patients with stages I and II thymoma suggests that evaluation of transcapsular invasion is of no clinical value in tumors that lack invasion of neighboring organs or the pleura. The data regarding the prognosis of stage II thymoma patients is somewhat heterogenous, with only some individuals having been treated with radiation therapy, suggesting the need for future randomized controlled trials.