The International Association for the Study of Lung Cancer Thymic Epithelial Tumor Staging Project: A Re-Assessment of the International Thymic Malignancy Interest Group/International Association for the Study of Lung Cancer Lymph Node Map for Thymic Epithelial Tumors for the Forthcoming Ninth Edition of the TNM Classification of Malignant Tumors.

INTRODUCTION: A lymph node map is the pillar on which accurate assignment and documentation of nodal classification stands. The International Thymic Malignancy Interest Group created the first map for thymic epithelial malignancies in conjunction with the eighth edition of the TNM classification, representing the first official TNM classification of thymic epithelial malignancies. The map was based on clinical experience and published studies, but it was largely empirical because of limited available data. Dissemination of the map and implementation of a standard thymic stage classification across the world in 2017 have provided more consistent and granular data. METHODS: More than twice as many cases of node involvement are available for analysis in the current database compared with that of the eighth edition database, allowing validation of many aspects of the eighth edition map. This article details the process and considerations for refinement of the thymic map for the ninth TNM used by the Thymic Domain of the Staging and Prognostic Factors Committee of the International Association for the Study of Lung Cancer. The committee evaluated a large international collaborative data set, published anatomical and clinical studies pertaining to lymph node spread from thymic epithelial tumors, in conjunction with the analysis underlying refinements of the TNM components for the ninth edition TNM classification. RESULTS: The node map boundaries of the N1 and N2 categories remain unchanged. Visual clarifications have been added to the nomenclature of nodal stations within these regions. CONCLUSIONS: On the basis of the recommendation to keep the N component unchanged for the ninth edition TNM classification, the lymph node map remains unchanged as well; however, clarifications have been added to facilitate clinical use.

Pathophysiology and human cancer risk assessment of pharmaceutical-induced thymoma in carcinogenicity studies.

Thymoma, a tumor of thymic lymphocytes or thymic epithelial cells (TECs), is a common spontaneous tumor in Wistar Han rats, especially in females with up to 18% incidence in controls. In addition to sex, there are rat strain differences in background incidence of thymomas such as Sprague Dawley versus Wistar Han rats. Human thymomas are very rare and without clear differences in incidence between males and females. Immunomodulatory and anti-inflammatory pharmaceutical drug classes, including Janus kinase inhibitors, increase the incidence of benign thymoma in two-year rat carcinogenicity studies. Potential non-genotoxic mechanisms that might contribute to the pathogenesis of thymoma development in one sex (female) Wistar Han rats include: (1) hormonal differences, (2) high proliferation rate of TECs, (3) delayed physiologic thymic involution, and/or (4) significant level of immunosuppression at high doses of a pharmaceutical drug. Factors to consider in the human cancer risk assessment of pharmaceutical-induced thymoma are: the genotoxicity of the test article, sex and strain of rats, exposure safety margins, and pathophysiologic differences and similarities of thymoma between rats and humans. Totality of weight of evidence approach and available data suggest thymomas observed in carcinogenicity studies of pharmaceutical drugs are not relevant for human risk at clinically relevant therapeutic doses.

Pleural Invasion Depth of Disseminated Nodules in Patients with Stage IVa or Recurrent Thymoma: Assessment, Curative Impact, and Surgical Outcomes.

BACKGROUND: Thymoma patients with pleural dissemination are difficult to manage, and their treatment strategy remains undefined. This study aimed to investigate the clinicopathologic features of these patients, focusing on the association between the depth of pleural invasion and prognosis. METHODS: Between 2003 and 2019, the study identified 120 disseminated lesions in 20 thymoma patients. Seven patients had de novo stage IVa thymoma and 13 were recurrent cases. Extrapleural pneumonectomy was performed for 8 patients and debulking surgery for 12 patients. Invasion depth of pleural tumors was classified into two groups: when the disseminated tumors invaded the pleura beneath the elastic layer, the tumor was diagnosed as Da, and when the disseminated tumors invaded the pleura beyond the elastic layer, the tumor was diagnosed as Db. RESULTS: Of 120 nodules, 31 (26%), found in eight patients with recurrent malignancies, were classified as Db. The pathologic status of the surgical margin (PSM) was positive in eight patients, seven of whom had Db nodules. The 5-year overall survival (OS) rate was 100% in the Da group and 75% in the Db group (P = 0.02). The 5-year progression-free survival (PFS) rate was 66.7% in the Da group and 25% in the Db group (P = 0.02). Cox univariate analysis showed that PFS was significantly influenced by the depth of invasion (P = 0.04) and PSM (P = 0.03). CONCLUSION: Depth of pleural invasion may influence survival outcomes for thymoma patients with pleural dissemination. The patients in this study with Da-disseminated nodules had an increased probability of a longer OS and PFS and tended to achieve negative PSM compared with the patients with Db.

Thymic epithelial tumor treatment in Japan: analysis of hospital cancer registry and insurance claims data, 2012-2014.

INTRODUCTION: Thymic epithelial tumors are a rare type of neoplasm. Accordingly, it is difficult to perform phase III trials in patients with thymic epithelial tumors, and thus, no standard treatment has been established for these tumors. In this study, we aimed to investigate the current status of thymic epithelial tumor treatment in Japan. METHODS: This retrospective observational study enrolled patients with thymic epithelial tumor whose data were recorded in a nationwide Hospital-based Cancer Registry that was linked with health insurance claims data for the registered patients between 2012 and 2014. The patients' treatment details were obtained from a health insurance claims database. RESULTS: A total of 813 patients with thymoma and 547 with thymic carcinoma were included in the analysis. Overall, 549 (67.5%) thymoma patients underwent surgical resection alone. Among patients with thymic carcinoma, 230 (42.0%) underwent initial surgery, and 124 (53.9%) received subsequent radiotherapy and chemotherapy. Chemotherapy regimens varied across the hospitals; overall, 21 and 22 regimens were used to treat thymoma and thymic carcinoma, respectively. Platinum-based combination regimens were predominantly selected for both diseases. CONCLUSIONS: This study revealed the real-world patterns of thymic epithelial tumor treatment in Japan. Although the nature of this study did not enable the determination of optimal treatment strategies, the simultaneous analysis of nationwide registry, insurance, efficacy and prognostic data may contribute to the establishment of a standard treatment strategy for rarely occurring cancers such as thymic epithelial tumor.

Radiographic Assessment of Objective Responses Using the ITMIG-Modified Criteria in Thymic Carcinoma.

INTRODUCTION: Pleural metastases are common among patients with thymic carcinoma. Accurate and consistent measurement of pleural lesions is often difficult because of their unique locations and growth patterns. To minimize intraobserver variability, the International Thymic Malignancies Interest Group (ITMIG) proposed modified criteria for measurement of tumor response for thymic epithelial tumors. METHODS: We conducted a retrospective review of the medical records of advanced or recurrent thymic carcinoma patients treated with chemotherapy between 1980 and 2016 in our institution. The best objective responses were assessed using the Response Evaluation Criteria in Solid Tumor version 1.1 (RECIST 1.1) and the ITMIG-modified criteria. RESULTS: A total of 26 patients were included in the present study. According to the RECIST criteria, 1 (3.8%) patient showed complete response (CR), and 13 (50.0%), 10 (38.5%), and 2 (7.7%) showed partial response (PR), stable disease (SD), and progressive disease (PD), respectively. All 26 patients had the same best overall response using the ITMIG criteria. The median time to progression (TTP) according to the RECIST criteria and the ITMIG-modified criteria was 5.5 months (95% confidence interval [CI] 3.8-8.6) and 7.0 months (95% CI 3.8-9.3), respectively (p = 0.993). CONCLUSION: The ITMIG-modified criteria showed a high concordance rate with RECIST 1.1 criteria in response assessment of thymic carcinoma.

Assessment of the prognostic role of neutrophil-to-lymphocyte ratio following complete resection of thymoma.

BACKGROUND: The introduction of the new TNM staging system for thymic epithelial malignancies produced a significant increase in the proportion of patients with stage I disease. The identification of new prognostic factors could help to select patients for adjuvant therapies based on their risk of recurrence. Neutrophil-to-lymphocyte ratio (NLR) has recently gained popularity as reliable prognostic biomarker in many different solid tumors. The aim of this study is to assess the utility of NLR evaluation as a prognostic marker in patients with surgically-treated thymoma. METHODS: A retrospective analysis was conducted among patients who underwent resection for thymoma in a single center. Patients were divided in two groups, under (low-NLR-Group = 47 patients, 60%) and above (high-NLR-Group = 32 patients, 40%) a ROC-derived NLR cut-off (2.27). Associations with clinical-pathological variables were analyzed; disease-free survival (DFS) was identified as the primary endpoint. RESULTS: Between 2007 and 2017, 79 patients had surgery for thymoma. Overall 5-year DFS was 80%. Univariate survival analysis demonstrated that NLR was significantly related to DFS when patients were stratified for TNM stage (p = 0.043). Five-year DFS in the low-NLR-Group and in the high-NLR-Group were respectively 100 and 84% in stage I-II, and 66 and 0% in stage III. TNM stage resulted as the only independent prognostic factor at multivariate analysis, with hazard ratio of 3.986 (95% CI 1.644-9.665, p = 0.002). CONCLUSIONS: High preoperative NLR seems to be associated to a shorter DFS in patients submitted to surgery for thymoma and stratified for TNM stage.

Prospective Study of Stereotactic Body Radiation Therapy for Thymoma and Thymic Carcinoma: Therapeutic Effect and Toxicity Assessment.

Stereotactic body radiation therapy (SBRT) is an important modality in treatment of tumors. We hypothesized that SBRT can achieve excellent local control with limited toxicity in patients with thymic tumors. A single-institution prospective study was performed with 32 patients who underwent SBRT of thymoma and thymic carcinoma between 2005 and 2014. Thirty-two patients including 39 target lesions were analyses in this study. Almost half of the patients (46.9%) were type C by histopathology and more than half (56.3%) were classified into stage IVA or IVB. The median dose of SBRT for gross tumor volume (GTV) was 56 Gy (range 49-70 Gy). Results showed that the response rate was 96.9% after SBRT and the median tumor shrinkage rate was 62.2% (range 3.8-100%). For the patients with both stage II-III and type A-B (n = 6), the median PFS was 28 months. In-field failure was only observed in 4 patients, and outside-field failure was seen in 2 patients. The local control rate was 81.25%. Patients treated with SBRT had an excellent local control with mild toxicities, which suggests that SBRT is feasible for the patients with thymic tumors who are unable to undergo either surgery or conventionally fractionated radiation therapy.

Assessment of the ITMIG Statement on the WHO Histological Classification and of the Eighth TNM Staging of Thymic Epithelial Tumors of a Series of 188 Thymic Epithelial Tumors.

INTRODUCTION: Thymic epithelial tumors (TETs) are rare intrathoracic malignancies that are categorized histologically according to the WHO classification, which was recently updated in 2015 on the basis of a consensus statement of the International Thymic Malignancy Interest Group (ITMIG); at the same time, the standard Masaoka-Koga staging system is scheduled to be replaced by the eighth edition of the TNM staging classification by the American Joint Committee on Cancer/Union for International Cancer Control consortium. Our objectives were to analyze the feasibility of assessing ITMIG consensus major and minor morphological and immunohistochemical criteria and the eighth edition of the TNM staging classification in a routine practice setting. METHODS: This is a single-center study conducted at the Louis-Pradel Hospital of Lyon University, one of the largest centers for TETs in France. Overall, a large surgical series of 188 TETs diagnosed in 181 patients between 2000 and 2014 at our center were analyzed. RESULTS: There were 89 men (49%) and 92 women (51%); 57 patients (31%) presented with myasthenia gravis at time of diagnosis. According to the WHO classification, there were nine type A thymomas (5%), 67 type AB thymomas (36%), 19 type B1 thymomas (10%), 46 type B2 thymomas (24%), 27 type B3 thymomas (14%), and 20 thymic carcinomas (11%). ITMIG consensus major criteria were identified in 100% of type A, AB, B1, and B2 thymomas. After restaging according to the eighth edition of the TNM staging classification, there were 127 stage I (84%), three stage II (2%), 17 stage IIIa (11%), no stage IIIb, two stage IVa (1%), and three stage IVb (2%) thymomas. Significant correlation between histological type and stage at diagnosis was maintained after restaging according the TNM classification. CONCLUSION: Comprehensive analysis of our well-characterized surgical series of 188 TETs indicates the feasibility and the diagnostic value of the ITMIG consensus statement on WHO histological classification and highlights the major switch in staging when the eighth edition of the TNM staging classification is applied.

Assessment of objective responses in thymic epithelial tumors using ITMIG modified criteria.

OBJECTIVES: Pleural metastases of thymic epithelial tumors (TETs) are relatively common, and this unique growth pattern makes the use of RECIST (response evaluation criteria in solid tumors) response criteria difficult. To standardize tumor measurement in TETs, the International Thymic Malignancy Interest Group (ITMIG) has proposed newly developed criteria. We compared evaluation of objective response between ITMIG modified criteria and RECIST 1.1 in patients with TET treated with systemic chemotherapy. PATIENTS AND METHODS: We retrospectively evaluated the tumor response of 40 patients with unresectable TET who were enrolled in a phase II clinical trial using ITMIG modified criteria, and compared the findings with prospectively evaluated tumor response assessed by RECIST 1.1. Agreement analyses for the response at each time point, including overall response and declaring progression, were performed and the time to progression (TTP) was also assessed using the two different measurements. RESULTS: The overall response rate assessed by the two methods did not differ significantly, with kappa value of 0.897. Agreement analysis for declaring progression of disease (PD) at the date of RECIST 1.1-designated PD showed 95% concordance rate with ITMIG modified criteria (p=1.000, kappa index=0.875). The median TTP according to RECIST 1.1 and ITMIG modified criteria was 8.4 and 7.9 months (p=0.983), respectively. Validation with another cohort of 27 TET patients treated with neoadjuvant chemotherapy also showed a 96% concordance rate in overall response between the two different criteria. CONCLUSIONS: ITMIG modified criteria showed a high concordance rate with RECIST 1.1 criteria in response assessment of TETs. Given the rarity of TETs, further evaluation of ITMIG modified criteria in a larger number of patients will be required before their implementation in clinical trials.

Comparison of CT and chemical-shift MRI for differentiating thymoma from non-thymomatous conditions in myasthenia gravis: value of qualitative and quantitative assessment.

AIM: To evaluate the usefulness of computed tomography (CT) and chemical-shift magnetic resonance imaging (MRI) in patients with myasthenia gravis (MG) for differentiating thymoma (THY) from thymic lymphoid hyperplasia (TLH) and normal thymus (NT), and to determine which technique is more accurate. MATERIALS AND METHODS: Eighty-three patients with generalised MG who underwent surgery were divided into the TLH/NT group (A; 65 patients) and THY group (B; 24 patients). Differences in qualitative characteristics and quantitative data (CT: radiodensity in Hounsfield units; MRI: signal intensity index [SII]) between groups were tested using Fisher's exact test and Student's t-test. Logistic regression models were estimated for both qualitative and quantitative analyses. At quantitative analysis, discrimination abilities were determined according to the area under the receiver operating characteristic (ROC) curve (AUROC) with computation of optimal cut-off points. The diagnostic accuracies of CT and MRI were compared using McNemar's test. RESULTS: At qualitative assessment, MRI had higher accuracy than CT (96.4%, 80/83 and 86.7%, 72/83, respectively). At quantitative analysis, both the radiodensity and SII were significantly different between groups (p<0.0001). For CT, at quantitative assessment, the AUROC of the radiodensity in discriminating between groups was 0.904 (optimal cut-off point, 20 HU) with an accuracy of 77.1% (64/83). For MRI, the AUROC of the SII was 0.989 (optimal cut-off point, 7.766%) with an accuracy of 96.4% (80/83), which was significantly higher than CT (p<0.0001). By using optimal cut-off points for cases with an erroneous diagnosis at qualitative assessment, accuracy improved both for CT (89.2%, 74/83) and MRI (97.6%, 81/83). CONCLUSION: Quantitative analysis is useful in evaluating patients with MG and improves the diagnostic accuracy of CT and MRI based on qualitative assessment. Chemical-shift MRI is more reliable than CT in differentiating THYs from non-thymomatous conditions.

Value of 18F-FDG PET/CT for Predicting the World Health Organization Malignant Grade of Thymic Epithelial Tumors: Focused in Volume-Dependent Parameters.

PURPOSE: We investigated whether preoperative parameters of 18F-FDG PET/CT were correlated with the World Health Organization (WHO) classification and/or Masaoka staging of thymic epithelial tumors. PATIENTS AND METHODS: We reviewed 61 patients retrospectively who were diagnosed with thymic epithelial tumors after surgical resection and PET/CT. A volume of interest was drawn on the primary lesion, using an SUV cutoff of 2.5, and metabolic indices such as SUVmax, metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were measured. RESULTS: There were 24 male patients (38.7%), and the mean (SD) age was 50.23 (12.54) years. The mean (SD) tumor size was 6.11 (3.41) cm. There were 22 low-risk thymomas (36.9%) (A, AB, B1), 32 high-risk thymomas (51.6%), and 7 thymic carcinomas (11.5%). The Masaoka stage was I in 15 (24.6%), II in 30 (49.2%), III in 11 (18.0%), and IV in 5 patients (8.2%). Mean (SD) SUVmax was 3.43 (1.01) in low-risk thymomas, 4.42 (1.70) in high-risk thymomas, and 8.23 (2.61) in thymic carcinoma; the differences were significant (P < 0.001). Mean (SD) MTV and TLG were 90.74 (114.56) and 229.36 (300.56) in low-risk thymomas, 80.82 (112.49) and 233.93 (340.91) in high-risk thymomas, and 90.63 (90.74) and 390.94 (437.62), respectively, in thymic carcinomas. MTV and TLG showed no correlation with the WHO classification. On receiver operating characteristic curve analysis, the cutoff value for discriminating thymomas and thymic carcinomas was 5.05. SUVmax and TLG were correlated with Masaoka stage. CONCLUSIONS: Although volume-dependent parameters were not correlated with the WHO classification, a significant relationship was observed between SUVmax and WHO classification and Masaoka stage.

The impact of neoadjuvant chemotherapy on the histopathological assessment of thymomas: a clinicopathological correlation of 28 cases treated with a similar regimen.

BACKGROUND: Twenty-eight patients treated with neoadjuvant chemotherapy for invasive thymoma are presented. METHODS: The patients were 16 men and 12 women between the ages of 23 and 75 years (mean = 50.8 years). All patients were treated with a similar modality consisting of three courses of cyclophosphamide, doxorubicin, cisplatin, and prednisone prior to their surgical resection. RESULTS: Grossly, all tumors were ill-defined invasive masses ranging in size from 5 to 18 cm in greatest dimension. Histological evaluation of the resected tumors showed a gamut of histological features, including necrosis, cystic changes, hemorrhage, histiocytic proliferation, calcifications, and cholesterol cleft granulomas in varying proportions. In addition, we found that some histological types of thymoma appeared to be affected less by neoadjuvant chemotherapy, while others, mainly those tumors with a more prominent lymphocytic component, showed more extensive histological changes. CONCLUSIONS: Based on the results of this study, it appears that the response to induction chemotherapy in thymomas may be determined by the histological characteristics of the tumor, with treatment-related changes being present predominantly in cases in which the tumor had a prominent lymphocytic component (WHO type B1 and B2), while tumor viability was highest in cases where the histological type corresponded to spindle cell and atypical thymomas (WHO types A and B3, respectively). In addition, it has to be noted that the histological changes attributed to treatment effect may also be seen in untreated tumors thereby not allowing for definitive separation of treated from nontreated thymomas.

Thymomas II: a clinicopathologic correlation of 250 cases with a proposed staging system with emphasis on pathologic assessment.

We present 250 cases of thymomas with emphasis on their clinical staging and follow-up. The patients were 120 males and 130 females between the ages of 13 and 92 years. Surgical resection was performed and histopathologic material evaluated in every case. Grossly, the tumors resected varied in size from 3 to 20 cm in greatest diameter. According to our proposed staging system, 31 cases were stage 0, 128 were stage I, 70 stage II, and 21 stage III at the time of resection. Histologically, approximately 53% of thymomas were of mixed histologic types. Follow-up information ranging from 1 to 16 years was obtained, showing significant statistical P values of .044 and .016 for overall and recurrence-free survival, respectively. We consider that our proposed staging system offers better stratification of cases and improved histologic definitions for proper staging of cases of thymoma.

Pathological comparative assessment of two cases of thymic cyst and cystic thymoma and review of the literature.

Cystic changes of the thymus are rare lesions. In addition to their appearance in non-neoplastic congenital and acquired conditions, they have been seen in association with certain malignancies of the thymus. Our aim is to highlight the possibility of confusing between benign and malignant thymus cysts having different cure approach. We report two thymic cyst cases, one congenital ectopic condition, and the other one, a cystic thymoma. Investigations included blood counts, echograms, and computed tomography. The cysts were excised by mediastinal route and examined pathologically. The final diagnosis was made only after histopathological examination of the surgery biopsy revealing two types of cystic thymic lesions: congenital and tumoral. Because thymic cysts may present malignant transformation, they represent a diagnostic challenge that is resolved only by surgical excision and histological examination. Due to cystic changes masking tumoral features in these cases, thorough sampling is required to ensure that a malignancy is not overlooked.

Assessment of objective responses using volumetric evaluation in advanced thymic malignancies and metastatic non-small cell lung cancer.

INTRODUCTION: Measurement of tumor response by standard response criteria is challenging in thymic malignancies, especially when the pleura is involved, as it often is in stage IV disease. In this study, we aimed to determine the effectiveness of volumetric response evaluation criteria in solid tumors (volumetrics) for evaluating response in patients with thymic malignancies treated on a phase II study of belinostat. METHODS: We evaluated the tumor responses of 25 patients with thymic cancer using computed tomography-based RECIST, World Health Organization (WHO), modified RECIST, and volumetrics. As a control, we assessed 37 patients with non-small cell lung cancer (NSCLC) with RECIST and volumetrics. RESULTS: Agreement analyses in 23 patients with thymic cancer at the time of RECIST-determined progressive disease (PD) compared volumetrics with RECIST, modified RECIST, and WHO criteria. Use of volumetrics was associated with 22% discordance compared with RECIST, 15% versus modified RECIST, and 22% versus WHO criteria. Volumetrics revealed PD 72 days earlier than RECIST (p = 0.016). In another cohort of 35 patients with NSCLC, there was 9% discordance between volumetrics and RECIST at the time of PD. Volumetrics demonstrated PD 32 days earlier than RECIST in NSCLC (p = 0.0078). CONCLUSIONS: Our study suggests that volumetrics might improve detection of PD. Prospective evaluation of this technique in a larger series of patients with thymic malignancies will be required.

Role of fluorine-flurodeoxyglucose positron emission tomography/computed tomography in preoperative assessment of anterior mediastinal masses.

OBJECTIVE: The purpose of the study was to explore the usefulness of fluorine-fluorodeoxyglucose positron emission tomography/computed tomography (F-FDG PET-CT) in the preoperative assessment of isolated anterior mediastinal lesions, especially in the planning of operative strategy (biopsy or upfront resection). METHODS: During the last 36 months, 19 consecutive patients (10 males, mean age 54+/-16 years) underwent PET-CT in the preoperative work-up of isolated anterior mediastinal diseases. Maximal transverse diameter at CT and the postoperative histology and Masaoka staging for thymomas were collected and related to the maximum standardised uptake values (SUVs). Thymomas were divided into low-risk thymoma (LRT=A, AB and B1) and high-risk thymoma (HRT=B2, B3 and C). RESULTS: There were 13 thymomas (six LRT and seven HRT), three lymphomas and three other primitive thymic tumours (one paraganglioma, two non-seminomatous germ cell tumours). In LRT, the mean SUV was 3.3+/-0.5 resulting significantly lower than HRT, 13.5+/-7 (p=0.009). The SUV in LRT was also significantly lower with respect to lymphoma, 12.4+/-4 (p=0.001), and the other primitive anterior mediastinal tumours, 8+/-0.8 (p=0.001). Between thymomas we found a significant correlation between Masaoka stage and SUV, r=0.718, p=0.006. No correlation was found between transverse diameters and SUV, r=0.141, p=0.6. CONCLUSIONS: In our experience, low SUV (<5) is associated with LRT and minimal invasive thymoma (Masaoka stages I-II) and, therefore, susceptible to upfront surgery. For lesions with an infiltrative aspect on CT scan associated with a higher SUV (>5), an open biopsy is mandatory to exclude mediastinal lymphomas or, in case of HRT, to address a neoadjuvant treatment.

Novel prognostic groups in thymic epithelial tumors: assessment of risk and therapeutic strategy selection.

PURPOSE: To assess the role of multimodality treatment on patients with thymic epithelial tumors (TETs) (i.e., thymomas and thymic squamous cell carcinoma) and to define the prognostic classes according to the Masaoka and World Health Organization histologic classification systems. METHODS AND MATERIALS: Primary surgery was the mainstay of therapy. Extended thymectomy was performed in all cases. The cases were primarily staged according to the Masaoka system. Adjuvant radiotherapy was given to patients diagnosed with Masaoka Stage II, III, and IVA TET. Adjuvant chemotherapy was administered in selected cases. RESULTS: We reviewed the records of 120 patients with TETs, with a mean follow-up of 13.8 years. Of the 120 patients, 98 (81.6%) received adjuvant radiotherapy. Of these 98 patients, Grade 1-2 pulmonary or esophageal toxicity was acute in 12 (12.2%) and late in 8 (8.2%). The median overall survival was 21.6 years. Of the 120 patients, 106 were rediagnosed and reclassified according to the World Health Organization system, and the survival rate was correlated with it. Three different prognostic classes were defined: favorable, Masaoka Stage I and histologic grade A, AB, B1, B2 or Masaoka Stage II and histologic grade A, AB, B1; unfavorable, Stage IV disease or histologic grade C or Stage III and histologic grade B3; intermediate, all other combinations. The 10- and 20-year survival rate was 95% and 81% for the favorable group, 90% and 65% for the intermediate group, and 50% and 0% for the unfavorable group, respectively. Local recurrence, distant recurrence, and tumor-related deaths were also evaluated. CONCLUSION: The analysis of our experience singled out three novel prognostic classes and the assessment of risk identified treatment selection criteria.

PET: other thoracic malignancies.

The vast majority of esophageal cancers are fluorodeoxyglucose (FDG) avid; the primary use for positron emission tomography (PET) in patients with esophageal cancer is in the detection of distant metastases, because known distant metastatic disease precludes surgical resection. High standardized uptake values (SUVs) may be predictive of poor prognosis. PET findings may be used to assess therapy response and evaluate for esophageal tumor recurrence after treatment. PET findings may be non-specific in different types of thymic lesions, although thymic carcinomas tend to be extremely FDG avid. PET can be helpful in detecting distant spread from invasive thymomas and thymic carcinomas. Similarly, PET may be used to assess the extent of disease in patients with malignant pleural mesothelioma, thereby facilitating optimal therapy approaches.