Clinical evaluation of a new tumour-node-metastasis staging system for thymic malignancies proposed by the International Association for the Study of Lung Cancer Staging and Prognostic Factors Committee and the International Thymic Malignancy Interest Group

Computed tomography radiomic feature analysis of thymic epithelial tumors: Differentiation of thymic epithelial tumors from thymic cysts and prediction of histological subtypes

PURPOSE

To investigate the value of computed tomography (CT) radiomic feature analysis for the differential diagnosis between thymic epithelial tumors (TETs) and thymic cysts, and prediction of histological subtypes of TETs.

MATERIALS AND METHODS

Twenty-four patients with TETs (13 low-risk and 9 high-risk thymomas, and 2 thymic carcinomas) and 12 with thymic cysts were included in this study. For each lesion, the radiomic features of a volume of interest covering the lesion were extracted from non-contrast enhanced CT images. The Least Absolute Shrinkage and Selection Operator (Lasso) method was used for the feature selection. Predictive models for differentiating TETs from thymic cysts (model A), and high risk thymomas + thymic carcinomas from low risk thymomas (model B) were created from the selected features. The receiver operating characteristic curve was used to evaluate the effectiveness of radiomic feature analysis for differentiating among these tumors.

RESULTS

In model A, the selected 5 radiomic features for the model A were NGLDM_Contrast, GLCM_Correlation, GLZLM_SZLGE, DISCRETIZED_HISTO_Entropy_log2, and DISCRETIZED_HUmin. In model B, sphericity was the only selected feature. The area under the curve, sensitivity, and specificity of radiomic feature analysis were 1 (95% confidence interval [CI]: 1-1), 100%, and 100%, respectively, for differentiating TETs from thymic cysts (model A), and 0.76 (95%CI: 0.53-0.99), 64%, and 100% respectively, for differentiating high-risk thymomas + thymic carcinomas from low-risk thymomas (model B).

CONCLUSION

CT radiomic analysis could be utilized as a non-invasive imaging technique for differentiating TETs from thymic cysts, and high-risk thymomas + thymic carcinomas from low-risk thymomas.

The Prognostic Role of the Number of Involved Structures in Thymic Epithelial Tumors: Results from the ESTS Database

BACKGROUND

The role of the number of involved structures (NIS) in thymic epithelial tumors (TETs) has been investigated for inclusion in future staging systems, but large cohort results still are missing. This study aimed to analyze the prognostic role of NIS for patients included in the European Society of Thoracic Surgeons (ESTS) thymic database who underwent surgical resection.

METHODS

Clinical and pathologic data of patients from the ESTS thymic database who underwent surgery for TET from January 2000 to July 2019 with infiltration of surrounding structures were reviewed and analyzed. Patients' clinical data, tumor characteristics, and NIS were collected and correlated with CSS using Kaplan-Meier curves. The log-rank test was used to assess differences between subgroups. A multivariable model was built using logistic regression analysis.

RESULTS

The final analysis was performed on 303 patients. Histology showed thymoma for 216 patients (71.3%) and NET/thymic carcinoma [TC]) for 87 patients (28.7%). The most frequently infiltrated structures were the pleura (198 cases, 65.3%) and the pericardium in (185 cases, 61.1%), whereas lung was involved in 96 cases (31.7%), great vessels in 74 cases (24.4%), and the phrenic nerve in 31 cases (10.2%). Multiple structures (range, 2-7) were involved in 183 cases (60.4%). Recurrence resulted in the death of 46 patients. The CSS mortality rate was 89% at 5 years and 82% at 10 years. In the univariable analysis, the favorable prognostic factors were neoadjuvant therapy, Masaoka stage 3, absence of metastases, absence of myasthenia gravis, complete resection, thymoma histology, and no more than two NIS. Patients with more than two NIS presented with a significantly worse CSS than patients with no more than two NIS (CSS 5- and 10-year rates: 9.5% and 83.5% vs 93.2% and 91.2%, respectively; p = 0.04). The negative independent prognostic factors confirmed by the multivariable analysis were incomplete resection (hazard ratio [HR] 2.543; 95% confidence interval [CI] 1.010-6.407; p = 0.048) and more than two NIS (HR 1.395; 95% CI 1.021-1.905; p = 0.036).

CONCLUSIONS

The study showed that more than two involved structures are a negative independent prognostic factor in infiltrative thymic epithelial tumors that could be used for prognostic stratification.

The International Association for the Study of Lung Cancer Thymic Epithelial Tumors Staging Project: Proposal for a Stage Classification for the Forthcoming (Ninth) Edition of the TNM Classification of Malignant Tumors

INTRODUCTION

A TNM-based system for all types of thymic epithelial tumors was introduced in the eighth edition of the TNM classification of thoracic malignancies. The Thymic Domain of the Staging and Prognostic Factors Committee of the International Association for the Study of Lung Cancer, composed of multispecialty international experts, was charged to develop proposals for the ninth edition. This article outlines the proposed definitions for the T, the N, and the M components and their combination into stage groups.

METHODS

A large central database of 11,347 patients with thymic epithelial tumors was assembled thanks to the contribution of the major thymic organizations worldwide and analyses were carried out for the T, the N, and the M components and the stage groups. Overall survival was the outcome measure for patients with completely and incompletely resected tumors, and recurrence for those with complete resection. When the number of patients was sufficient, analyses were performed separately for thymomas, thymic carcinomas, and neuroendocrine thymic tumors.

RESULTS

Tumor size is included in the T1 category as T1a (≤5cm) and T1b (>5 cm); the mediastinal pleura is dropped as a T descriptor; invasion of the lung or phrenic nerve is reclassified as T2 (instead of T3). No changes are proposed for the N and the M components from the eighth edition. The stage groups remain the same.

CONCLUSIONS

The proposed changes for the ninth edition of the TNM classification set the stage for further progress in the future for these rare tumors.

Risk factor analysis for major mediastinal vessel invasion in thymic epithelial tumors based on multi-slice CT Imaging

Objective

To explore the characteristics and risk factors for major mediastinal vessel invasion in different risk grades of thymic epithelial tumors (TETs) based on computed tomography (CT) imaging, and to develop prediction models of major mediastinal artery and vein invasion.

Methods

One hundred and twenty-two TET patients confirmed by histopathological analysis who underwent thorax CT were enrolled in this study. Clinical and CT data were retrospectively reviewed for these patients. According to the abutment degree between the tumor and major mediastinal vessels, the arterial invasion was divided into grade I, II, and III (< 25%, 25 - 49%, and ≥ 50%, respectively); the venous invasion was divided into grade I and II (< 50% and ≥ 50%). The degree of vessel invasion was compared among different defined subtypes or stages of TETs using the chi-square tests. The risk factors associated with TET vascular invasion were identified using multivariate logistic regression analysis.

Results

Based on logistic regression analysis, male patients (β = 1.549; odds ratio, 4.824) and the pericardium or pleural invasion (β = 2.209; odds ratio, 9.110) were independent predictors of 25% artery invasion, and the midline location (β = 2.504; odds ratio, 12.234) and mediastinal lymphadenopathy (β = 2.490; odds ratio, 12.06) were independent predictors of 50% artery invasion. As for 50% venous invasion, the risk factors include midline location (β = 2.303; odds ratio, 10.0), maximum tumor diameter larger than 5.9 cm (β = 4.038; odds ratio, 56.736), and pericardial or pleural effusion (β = 1.460; odds ratio, 4.306). The multivariate logistic model obtained relatively high predicting efficacy, and the area under the curve (AUC), sensitivity, and specificity were 0.944, 84.6%, and 91.7% for predicting 50% artery invasion, and 0.913, 81.8%, and 86.0% for 50% venous invasion in TET patients, respectively.

Conclusion

Several CT features can be used as independent predictors of ≥50% artery or venous invasion. A multivariate logistic regression model based on CT features is helpful in predicting the vascular invasion grades in patients with TET.

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.

Prognostic factors and genetic markers in thymic epithelial tumors: A narrative review

Thymic epithelial tumors (TET) are a group of rare neoplasms of the anterior mediastinum comprising thymomas and thymic carcinomas. The carcinogenesis of TET is mostly unknown. Many studies, mostly retrospective case series, have tried to establish prognostic factors in TET. TET is a very heterogeneous group of tumors with many subtypes for which diagnosis and treatment remains a very challenging task. Despite the disparities among retrospective studies, there are some prognostic factors that are more pertinent such as the completeness of resection, TNM stage and the Masaoka-Koga classification. On the other hand, the identification of different genetic pathways that result in the pathogenesis of TET represents a fascinating field of study that could possibly lead to the development of new targeted therapies. The aim of this review is to discuss the different prognostic factors and genetic markers of TET. The meticulous use of national and international databases could provide sufficient number of patients in order to draw more valid conclusions.

Prognostic Value of Preoperative Serum Carcinoembryonic Antigen for Overall Survival and Recurrence-Free Survival in Resectable Thymic Epithelial Tumors

Introduction: Tumor markers have been shown to be closely related to the long-term survival of patients with cancer and the recurrence of various malignant tumors. However, their role in thymic epithelial tumors (TETs) remains to be elucidated. We aimed to investigate whether the preoperative tumor biomarkers carcinoembryonic antigen (CEA) and neuron-specific enolase (NSE) could serve as independent predictors of postoperative prognosis in patients with TETs. Materials and Methods: We retrospectively included a total of 111 patients with TETs who underwent thymectomy at our hospital. Cox regression analysis was used to evaluate the statistical significance of CEA and NSE as independent predictors of overall survival (OS) and recurrence-free survival (RFS). Kaplan-Meier curves were used to present the results of our survival analyses. Results: Cox regression analysis showed that T stage, World Health Organization (WHO) histologic type, tumor size, and CEA levels served as independent prognostic factors for OS (P < .05). Whereas for RFS, multivariate analysis showed that only T stage, WHO histologic type, and drinking history were independently associated with it (P < .05). Conclusion: Our study found that preoperative serum CEA levels and tumor size may be strong predictors of postoperative OS in patients with TETs.

Masaoka-Koga and TNM Staging System in Thymic Epithelial Tumors: Prognostic Comparison and the Role of the Number of Involved Structures

Simple Summary

Thymic epithelial tumors were originally staged using the Masaoka–Koga staging system, even if recently the adoption of the tumor node metastases staging system was recommended. However, it remains controversial as to which staging system is the most effective in prognosis prediction for these patients. The aim of this study was to analyze the prognostic effectiveness of these staging systems and to verify a possible improvement.

Abstract

Background: The aim of this study was to evaluate the Masaoka–Koga and the tumor node metastases (TNM) staging system in thymic epithelial tumors (TET) considering possible improvements. Methods: We reviewed the data of 379 patients who underwent surgical resection for TET from 1 January 1985 to 1 January 2018, collecting and classifying the pathological report according to the Masaoka–Koga and the TMN system. The number of involved organs was also considered as a possible prognostic factor and integrated in the two staging systems to verify its impact. Results: Considering the Masaoka–Koga system, 5- and 10-year overall survival (5–10YOS) was 96.4% and 88.9% in stage I, 95% and 89.5% in stage II and 85.4% and 72.8% in stage III (p = 0.01), with overlapping in stage I and stage II curves. Considering the TNM system, 5–10YOS was 95.5% and 88.8% in T1, 84.8% and 70.7% in T2 and 88% and 76.3% in T3 (p = 0.02), with overlapping T2–T3 curves. Including the number of involved structures, in Masaoka–Koga stage III, patients with singular involved organs had a 100% and 76.6% vs. 87.7% 5–10YOS, which was 76.6% in patients with multiple organ infiltration. Considering the TNM, T3 patients with singular involved structures presented a 5–10YOS of 100% vs. 62.5% and 37.5% in patients with multiple organ involvement (p = 0.07). Conclusion: The two staging systems present limitations due to overlapping curves in early Masaoka–Koga stages and in advanced T stages for TNM. The addition of the number of involved organs seems to be a promising factor for the prognosis stratification in these patients.

Nomogram predict relapse-free survival of patients with thymic epithelial tumors after surgery

Background

Hematological indicators and clinical characteristics play an important role in the evaluation of the progression and prognosis of thymic epithelial tumors. Therefore, we aimed to combine these potential indicators to establish a prognostic nomogram to determine the relapse-free survival (RFS) of patients with thymic epithelial tumors undergoing thymectomy.

Methods

This retrospective study was conducted on 156 patients who underwent thymectomy between May 2004 and August 2015. Cox regression analysis were performed to determine the potential indicators related to prognosis and combine these indicators to create a nomogram for visual prediction. The prognostic predictive ability of the nomogram was evaluated using the consistency index (C-index), receiver operating characteristic (ROC) curve, and risk stratification. Decision curve analysis was used to evaluate the net benefits of the model.

Results

Preoperative albumin levels, neutrophil-to-lymphocyte ratio (NLR), T stage, and WHO histologic types were included in the nomogram. In the training cohort, the nomogram showed well prognostic ability (C index: 0.902). Calibration curves for the relapse-free survival (RFS) were in good agreement with the standard lines in training and validation cohorts.

Conclusions

Combining clinical and hematologic factors, the nomogram performed well in predicting the prognosis and the relapse-free survival of this patient population. And it has potential to identify high-risk patients at an early stage. This is a relatively novel approach for the prediction of RFS in this patient population.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08585-y.

Prognostic factors for survival in advanced thymomas: The role of the number of involved structures

BACKGROUND AND OBJECTIVES

The Masoka-Koga and tumor node metastases staging systems for thymoma are based on structures involved, but the prognostic role of the number of infiltrated/involved structures is still debated. We analyzed the prognostic role of involved structures and their combinations in locally advanced thymomas patients.

METHODS

Data on 174 surgically treated locally advanced thymoma patients from 1/01/1990 to 31/12/2015 were reviewed. Clinical and pathological characteristic, involved structures, number of involved structures and different combinations were correlated to cancer specific survival (CSS) using Kaplan-Meier product-limit method.

RESULTS

Five and 10-year CSS was 92% and 87%. Masaoka Stage 3 (p < 0.001), absence of pericardial involvement (p = 0.001), number of involved structures (p = 0.018), R0 (p < 0.001) and adjuvant radiotherapy (p = 0.008) were favorable prognostic CSS factors. A significant better prognosis was present in ≤2 involved structures vs >2 involved structures (5- and 10-year CSS: 95% and 93% vs. 80% and 51%). Multivariable analysis confirmed as independent prognostic factor R0 (p = 0.033, hazard ratio [HR]: 0.093, 95% confidence interval [CI] 0.010-0.827) and number of involved structures (p = 0.046, HR: 0.187, 95% CI: 0.036-0.968). In Masaoka Stage 3, patients with ≤2 involved structures had a significant better CSS than patients with >2 (10-year CSS: 98% vs. 73%, p = 0.008).

CONCLUSIONS

The number of involved structures and the concomitant involvement of the pericardium seems to be associated with a poor prognosis in surgically treated advanced thymoma patients.

Different View on Tumor Size Dilemma in Tumor-Node-Metastasis Staging System for Thymoma

BACKGROUND

Although tumor size is included in the definition of T descriptor in the tumor-node-metastasis (TNM) classification of many solid tumors, it is not considered for thymomas. This study aimed to assess the relationship of tumor diameters (the largest tumor diameter [LTD] and the mean tumor diameter [MTD]) with survival in thymoma patients undergoing surgical resection in a single center.

METHODS

The study included 127 thymoma patients (age, 49.2 ± 15.2 years; 65 males), who were evaluated based on pathological tumor sizes according to the LTD and MTD ([largest diameter + shortest diameter] / 2) and divided into three subgroups for each parameter as: patients with an LTD of ≤5 cm, 5.1 to 10 cm, and >10 cm and patients with an MTD of ≤5, 5.1 to 10, and >10 cm.

RESULTS

In thymoma patients, survival significantly differed according to the presence of myasthenia gravis (p = 0.018), resection status (R0 or R1; p = 0.001), T status (p = 0.015), and the Masaoka-Koga stage (p = 0.003). In the LTD subgroups, the overall survival of those with R0 resection was lower in those with an LTD of 5.1 to 10 cm than in those with an LTD of ≤5 cm (p = 0.051) and significantly lower in those with an MTD of 5.1 to 10 cm than in those with an MTD of ≤5 cm (p = 0.027). In the MTD subgroups, survival decreased as the tumor size increased.

CONCLUSION

Both smaller tumor size and complete resection are associated with better survival in thymoma patients. Therefore, the largest or the mean tumor size might be considered as a criterion in the TNM staging for thymoma.

Thymic Malignancy-Updates in Staging and Management

Thymomas are relatively indolent tumors that present with locally advanced disease in 30% of the patients. Thymic carcinoma is a more aggressive histology with shorter disease-free and overall survival. Early-stage tumors are managed best with complete resection. Multimodal therapy is the standard of care for locally advanced tumors and neoadjuvant therapy may help improve respectability. Stage and complete resection are the strongest prognostic factors for long-term survival. Based on early experience, targeted and immunotherapies have shown limited promise in advanced disease.

Prognostic factors of stage I thymic epithelial tumors

OBJECTIVE

According to the tumor-node-metastasis classification for thymic malignancies, the proportion of patients diagnosed with stage I is expected to increase significantly. However, whether those patients have homogenous clinicopathological features and survival has not been fully evaluated.

METHODS

We reviewed 153 consecutive patients with stage I thymic epithelial tumors (133 thymomas, 15 thymic carcinomas, and 5 neuroendocrine tumors) who underwent complete resection at our institution between 2001 and 2016 and evaluated the prognostic significance of their clinicopathological factors.

RESULTS

The stage I patients accounted for 78% of all thymic epithelial tumors. The 5-year overall survival and recurrence-free survival rates of the 153 patients were 94% and 80%, respectively. The patients with the histology of thymic carcinoma or neuroendocrine tumor and with a tumor larger than 5.0 cm showed significantly worse recurrence-free survival in multivariate analysis (p = 0.027 and 0.038, respectively). Only the tumor size was revealed as a significant prognostic factor for recurrence-free survival when limited in the 133 cases of thymoma (p = 0.048).

CONCLUSIONS

Patients with large tumors showed significantly worse recurrence-free survival than those with small tumors both in stage I thymic epithelial tumors and thymomas.

Tumor size as a prognostic factor in limited-stage thymic epithelial tumors: A multicenter analysis

OBJECTIVE

The prognostic significance of tumor size in thymic epithelial tumors (TETs) has not been fully evaluated. We aimed to clarify the prognostic value of tumor size in limited-stage and advanced-stage TETs.

METHODS

Clinical records of patients with completely resected TETs were retrospectively collected from 4 tertiary centers between January 2000 and February 2013. Information on the Masaoka-Koga stage was available for 1215 patients (M-K group), and 433 patients were classified according to the eighth edition of the Tumor-Node-Metastasis staging system (TNM group). Limited-stage and advanced-stage TETs were defined according to whether they were confined within the surrounding fatty tissues without invasion. The optimal cutoff value was selected using a maximally selected log-rank statistic.

RESULTS

The median tumor size was 6.0 ± 2.8 cm in the M-K group and 6.5 ± 3.0 cm in the TNM group. In the multivariable analysis, tumor size had a significant effect on both overall survival (P = .003) and recurrence-free survival (P < .001) for limited-stage tumors (M-K stage I or II or TNM stage I), but not for advanced-stage tumors (M-K stage III or IV or TNM stage II-IV; P = .349 for overall survival and P = .439 for recurrence-free survival). The optimal cutoff value for tumor size was >5.5 cm for both overall survival and recurrence-free survival in limited-stage TETs.

CONCLUSIONS

Tumor size is an independent prognostic factor in patients with completely resected limited-stage TETs and a cutoff value >5.5 cm might help clinicians enact proper treatment strategies and surveillance.

High Neutrophil Count as a Negative Prognostic Factor for Relapse in Patients with Thymic Epithelial Tumor

PURPOSE

Preoperative neutrophil count is reportedly associated with poor prognosis in cancer patients. This study aimed to investigate the clinical significance of pre-treatment peripheral blood cell counts in patients with thymic epithelial tumors (TETs).

METHODS

A retrospective review of 71 patients with completely resected TETs [64 thymoma, 6 thymic carcinoma, and 1 thymic neuroendocrine tumor] between 2000 and 2018 was conducted. Associations between tumor recurrence and pre-treatment peripheral blood cell counts of leukocytes (WBC), neutrophils (Neut), lymphocytes (Lymph), monocytes (Mono), and platelets (Plt) were analyzed. Optimal cut-off points were selected using receiver operating characteristic curve analysis to predict tumor recurrence.

RESULTS

High WBC (≥ 7000), Neut (≥ 4450), and Plt (≥ 226 × 10³) counts had significantly poor relapse-free survival (RFS), but high Lymph (≥ 1950) and Mono (≥ 400) did not. High Neut had the strongest correlation with recurrence (area under curve, 0.800); we focused on the analysis between high-Neut and low-Neut groups. High Neut count significantly correlated with smoking history, pre-treatment C-reactive protein level, and advanced stage; high Neut count and aggressive histology tended to show correlations. RFS was significantly poorer in the high-Neut group than in the low-Neut group (p = 0.003), with 5-year RFS rates of 63.8% and 96.8%, respectively. High Neut count was a significant adverse predictor for RFS and cumulative incidence of recurrence (p = 0.005 and p < 0.001, respectively). The risk scoring system comprising high Neut count, advanced stage, and aggressive histology demonstrated better prognostic ability than any prognostic factors alone.

CONCLUSIONS

High Neut count significantly correlated with TET recurrence, suggesting a negative prognostic effect of latent inflammation in TET patients.

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.

Can 18F-FDG PET predict the grade of malignancy in thymic epithelial tumors? An evaluation of only resected tumors

Objective

Although 18-fluorine fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET) is thought to be useful for predicting the histological grade of thymic epithelial tumors (TETs), it remains controversial. To date, just a few of many previous studies have included only resected cases. Therefore, we investigated ¹⁸F-FDG PET findings only in patients with resected TETs.

Patients and methods

A total of 112 patients with TETs consisting of 92 thymomas and 20 thymic carcinomas (TCs), resected at two institutes (Shizuoka Cancer Center [Shizuoka] and National Cancer Center Hospital [Tokyo]) between October 2002 and December 2015, were evaluated. Spearman rank correlation coefficient was used to assess the association between the maximum standardized uptake value (SUVmax) in the tumor and both the histological subtype and tumor stage. The cutoff value of SUVmax for differentiating thymoma from TC was calculated.

Results

The SUVmax was strongly related to both the World Health Organization (WHO) histological subtype and tumor stage based on the eighth edition of the tumor-node-metastasis (TNM) classification (Spearman rank correlation coefficient =0.485 and 0.432; p = 0.000 and 0.000, respectively). There was a significant difference between thymoma and TC. The optimal SUVmax cutoff value for differentiating thymoma from TC was 4.58 (sensitivity: 80% and specificity: 78.3%). In contrast, there was no significant difference between low-risk (type A, AB, and B1) and high-risk (type B2 and B3) thymoma, or between type B3 thymoma and the other subtypes.

Conclusion

Our results suggest that ¹⁸F-FDG PET is useful for differentiating thymoma from TC, but not for predicting the histologic grade of thymoma.

Evaluation of the new TNM-staging system for thymic malignancies: impact on indication and survival

Background

The objective of this study is the evaluation of the Masaoka-Koga and the International Association for the Study of Lung Cancer (IASLC)/International Thymic Malignancy Interest Group (ITMIG) proposal for the new TNM-staging system on clinical implementation and prognosis of thymic malignancies.

Methods

A retrospective study of 76 patients who underwent surgery between January 2005 and December 2015 for thymoma. Kaplan–Meier survival analysis was used to determine overall and recurrence-free survival rates.

Results

Indication for surgery was primary mediastinal tumor (n = 55), pleural manifestation (n = 17), or mediastinal recurrence (n = 4) after surgery for thymoma. Early Masaoka-Koga stages I (n = 9) and II (n = 14) shifted to the new stage I (n = 23). Advanced stages III (Masaoka-Koga: n = 20; ITMIG/IASLC: n = 17) and IV (Masaoka-Koga: n = 33; ITMIG/IASLC: n = 35) remained nearly similar and were associated with higher levels of WHO stages. Within each staging system, the survival curves differed significantly with the best 5-year survival in early stages I and II (91%). Survival for stage IV (70 to 77%) was significantly better compared to stage III (49 to 54%). Early stages had a significant longer recurrence-free survival (86 to 90%) than advanced stages III and IV (55 to 56%).

Conclusions

The proportion of patients with IASLC/ITMIG stage I increased remarkably, whereas the distribution in advanced stages III and IV was nearly similar. The new TNM-staging system presents a clinically useful and applicable system, which can be used for indication, stage-adapted therapy, and prediction of prognosis for overall and recurrence-free survival.

Prognostic impact of tumour size in completely resected thymic epithelial tumours

OBJECTIVES

The T descriptor of thymic epithelial tumours proposed by the International Association for the Study of Lung Cancer and the International Thymic Malignancy Interest Group as well as the Masaoka-Koga system is defined by the anatomical extent of primary tumours, regardless of their size. However, the prognostic significance of tumour size in thymic epithelial tumours has not been fully elucidated.

METHODS

We evaluated the prognostic significance of tumour size in 154 consecutive patients with thymic epithelial tumours including 124 thymomas, 21 thymic carcinomas and 9 neuroendocrine tumours, who underwent complete resection between 2001 and 2014.

RESULTS

Among all tumours, the median tumour size was 4.9 cm. The median thymoma, thymic carcinoma and neuroendocrine tumour sizes were 4.8, 5.7 and 5.8, respectively, although the differences were not significant. In survival analysis, the 5- and 10-year overall survival (OS) and recurrence-free survival (RFS) rates for all patients were 91 and 81%, and 80 and 69%, respectively. Under the stratification of tumour size, no trend was observed for OS, whereas RFS showed stepwise deterioration as tumour size increased. For 119 patients with Stage I disease, RFS showed deterioration as tumour size increased. Multivariate analysis revealed that tumour size >4.0 cm was an independent prognostic factor for worsening RFS (P = 0.03).

CONCLUSIONS

Patients with tumours >4.0 cm showed significantly worse outcomes in RFS compared with those with smaller tumours. This relationship was also noted in patients with Stage I disease.

Metastatic Thymoma in a Scarlet Macaw ( Ara macao )

A 49-year-old female scarlet macaw ( Ara macao ) was presented with a mass in the cervical region. The bird showed no evidence of pain or discomfort, it swallowed food normally, and its breathing pattern was unremarkable. Results of contrast radiographic imaging revealed a well-demarcated mass in the right cervical region not related to the crop. After surgical resection and histopathologic evaluation, a malignant nodular stage of an epithelioid cortical-type thymoma was diagnosed. One year later, metastasis of the thymoma to the lung was diagnosed and confirmed at postmortem examination. The final diagnosis was corrected to malignant nodular stage of an epithelioid cortical-type thymoma with metastasis to the lung. This is the first report in an avian species of a malignant thymoma with metastasis to the lung after complete resection of the initial cervical thymoma and a survival time of 1 year.

Increased expression of microRNA-503 and reduced expression of kangai-1 in B-cell non-Hodgkin's lymphoma

The aim of the present study was to determine the expression levels of microRNA-503 (miR-503) and the tumor suppressor gene, kangai-1 (KAI1), in B-cell non-Hodgkin's lymphoma (B-NHL). A total of 45 patients with B-NHL (including 29 cases with stage III/IV disease and 16 cases with stage I/II disease) were enrolled in this study. In addition, 26 patients with reactive lymphoid hyperplasia (RLH) were enrolled as the control patients. Reverse transcription-quantitative polymerase chain reaction was performed in order to measure the expression levels of miR-503 in B-NHL and RLH tissues, and to detect the expression levels of miR-503 and KAI1 in peripheral blood samples. In addition, KAI1 expression levels in B-NHL and RLH tissues were detected using western blotting and immunohistochemical analysis. The expression levels of miR-503 were found to be significantly increased in the tissues and peripheral blood of B-NHL patients when compared with those in RLH patients (P<0.05). However, KAI1 was strongly expressed in RLH tissues and weakly expressed in B-NHL tissues. Furthermore, the expression levels of KAI1 were significantly decreased in the tissues and peripheral blood of B-NHL patients when compared with those in the tissues and peripheral blood of RLH patients (P<0.05). The expression levels of miR-503 in the tissues and peripheral blood of patients with stage III/IV B-NHL were significantly higher compared with those with stage I/II B-NHL (P<0.05). By contrast, the expression levels of KAI1 in stage III/IV B-NHL tissues were significantly higher compared with those in stage I/II B-NHL tissues (P<0.05). In conclusion, miR-503 was highly expressed, whereas KAI1 was poorly expressed, in the tissues and peripheral blood of B-NHL patients. Thus, miR-503 may have an application as a novel therapeutic and diagnostic marker in B-NHL patients.