Thymoma: a multivariate analysis of factors predicting survival

TNM Staging System in Thymoma: A Critical Appraisal?

Thymomas are rare tumors of the anterior mediastinum with peculiar clinical and pathological features. They have been deeply analyzed by pioneer authors, who strictly linked their name to the main pathological and staging classifications. Before the latest edition of the WHO classification of thymic epithelial tumors, the history of thymoma pathological classification inherited the name of the pathologists who systematically addressed the issue, from Levine-Rosai to Muller-Hermelink. Similarly, the thymoma staging system is intimately related to the name of two surgeons, Masaoka and Koga, who historically dealt with this disease. More recently, the traditional tumor-nodes-metastasis (TNM) system has been developed for the staging of this condition, in a rational attempt to put thymomas in conformity with the other solid tumors. The efforts of the International Thymic Malignancies Interest Group (ITMIG) and the Thymic Domain of the Staging and Prognostic Factors Committee (TD-SPFC) of the International Association for the Study of Lung Cancer (IASLC) resulted in the TNM classification of thymic tumors, which have been included in the eighth edition of the American Joint Committee on Cancer's (AJCC) Cancer Staging Manual. Herein, we report a narrative review of the evolution of the thymic epithelial tumors (TET) staging system and present a critical appraisal of the actual TNM classification compared with the historical Masaoka-Koga classification, with special focus on the proposal for the ninth edition of the TNM, expected in 2024.

The International Association for the Study of Lung Cancer Thymic Epithelial Tumors Staging Project: Proposals for the N and the M Components for the Forthcoming (Ninth) Edition of the TNM Classification of Malignant Tumors

INTRODUCTION

Stage classification is an important underpinning of management in patients with cancer and rests on a combination of three components-T for tumor extent, N for nodal involvement, and M for distant metastases. This article details the revision of the N and the M components of thymic epithelial tumors for the ninth edition of the TNM classification of malignant tumors proposed by the Thymic Domain of the International Association for the Study of Lung Cancer Staging and Prognostic Factors Committee.

METHODS

The N and M components of the eighth edition staging system were verified by a large international collaborative data source through a data-driven analysis. A total of 9147 cases were included for analysis, including 7662 thymomas, 1345 thymic carcinomas, and 140 neuroendocrine thymic tumors.

RESULTS

Lymph node involvement rates were 1.5% in thymomas and 17.6% and 27.7% in thymic carcinomas and neuroendocrine thymic tumors, respectively. Rates of lymph node metastasis were increasingly higher in tumors with higher T stage and higher-grade histologic type. Survival analysis validated the differences in the N and M categories proposed in the eighth edition staging system. Good discrimination in overall survival was detected among pathologic (p)N and pM categories in patients with thymoma and thymic carcinoma.

CONCLUSIONS

No changes are proposed from the eighth edition for the N and M components. The proposed stage classification will provide a useful tool for management of the disease among the global thymic community.

Long-term outcomes following surgical treatment for thymic epithelial tumor in Japan and an analysis of prognostic factors based on the Japanese Association for Research on the Thymus nationwide database

PURPOSE

Patients with a thymic epithelial tumor (TET), comprising thymoma, thymic carcinoma (TC), and thymic neuroendocrine neoplasm (TNEN), are rarely encountered. The present study was conducted to determine the recent outcomes of surgical treatment for TET in Japan and clarify the significance of prognostic factors by analyzing a nationwide database created by the Japanese Association for Research on the Thymus (JART).

METHODS

The JART database includes records of 2471 thymoma, 285 TC, and 56 TNEN cases surgically treated between 1991 and 2010. At the time of the final follow-up examination, 439 patients had died, with tumor the cause of death in 188. The disease-specific survival was examined using the Kaplan-Meier method, with Cox's proportional hazards model utilized to determine independent prognostic factors.

RESULTS

The 10-year survival rate according to TNM-based Stage I, II, IIIA, IIIB, IVA, and IVB classification was 98.7%, 76.8%, 85.0%, 68.9%, 66.2%, and 59.8%, respectively. The T factor, M factor, and tumor size were independent prognostic factors in both thymoma and thymic carcinoma cases, while the N factor had tendency to be a prognostic factor in thymoma but not in thymic carcinoma cases. The WHO histological type was an independent factor in thymoma cases.

CONCLUSION

The significance of pathology and TNM classification as prognostic factors was confirmed.

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.

Thymic Epithelial Tumors: An Evolving Field

Despite their rarity, thymic epithelial tumors (TETs) have attracted much interest over the years, leading to an impressive number of histological and staging classifications. At present, TETs are divided by the WHO classification into four main subtypes: type A, type AB, and type B thymomas (subdivided into B1, B2, and B3), and thymic carcinomas, going from the more indolent to the most aggressive ones. Among many debated staging proposals, the TNM and the Masaoka-Koga staging systems have been widely accepted and used in routine practice. The four-tiered histological classification is symmetrically mirrored by the molecular subgrouping of TETs, which identifies an A-like and an AB-like cluster, with frequent GTF2I and HRAS mutations; an intermediate B-like cluster, with a T-cell signaling profile; and a carcinoma-like cluster comprising thymic carcinomas with frequent CDKN2A and TP53 alterations and a high tumor molecular burden. Molecular investigations have opened the way to tailored therapies, such as tyrosine kinase inhibitors targeting KIT, mTOR, and VEGFR, and immune-checkpoints that have been adopted as second-line systemic treatments. In this review, we discuss the crucial events that led to the current understanding of TETs, while disclosing the next steps in this intriguing field.

Post-Operative Outcomes Associated With Open Versus Robotic Thymectomy: A Propensity Matched Analysis

To compare post-operative outcomes associated with thymectomy performed using either open or robotic approaches. Retrospective cohort study from a single-center prospective registry consisting of patients undergoing thymectomy between 2000 and 2020. Patients were grouped according to surgical approach (open vs robotic). A propensity-score matching analysis was performed in a 2:1 open to robotic ratio, and surgical outcomes were evaluated. We analyzed 234 thymectomies (155 open; 79 robotic). Myasthenia gravis was present in 23.2% and 32.9% (P = 0.249) in the open and in the robotic group, respectively. All covariates were balanced in the matched groups (open n = 114; robotic n =5 9), except lesion size. The robotic approach was significantly associated with shorter surgical time (median 95 vs 65 minutes, P < 0.001), lesser clinical (21.1% vs 6.8%, P = 0.016) and surgical (11.4% vs 1.7%, P = 0.036) complications during the same hospitalization, less Clavien-Dindo grade 2 or higher complication rates (28.1 vs 15.3%, P = 0.048), chest tube duration (median: 3 vs 0 days, P < 0.001) and in-hospital length of stay (median: 5 vs 0 days, P < 0.001). Bleeding (P = 0.214), ICU length of stay (P = 0.167), reoperation rate (open, 1.8% vs robotic 0%), 90-day mortality (P = 0.341) and readmission rate post discharge (P = 0.277) were similar between the groups. In the matched population with primary thymic epithelial tumors, the completeness of resection rate was similar (open, 92.1% vs robotic 96.8%, P = 0.66.). Robotic thymectomy is associated with improved post-operative outcomes when compared to open thymectomy, without compromising the goals of oncologic surgery. Longer follow-up is needed to ensure oncologic equivalence.

Evaluation of the role of postoperative radiotherapy in locally invasive thymoma: A propensity-matched study based on the SEER database

OBJECTIVES

No consensus was reached on the efficacy of postoperative radiotherapy (PORT) in locally invasive thymomas because of the rarity of the thymic epithelial and the variations of study results. Therefore, we aimed to explore the efficacy of PORT in locally invasive thymomas using the Surveillance, Epidemiology, and End Results (SEER) database.

METHODS

Patients diagnosed with thymomas from 2004 to 2016 were identified using the SEER database. Prognostic factors of cancer-specific survival (CSS) and overall survival (OS) were identified using univariate and multivariate Cox regression analyses.Propensity score matching (PSM) was performed to balance the baseline characteristics.

RESULTS

A total of 700 eligible patients were identified. After PSM, 262 paired patients were selected from the two groups, those who received or did not receive PORT. Receiving PORT improved CSS and OS before and after PSM. In the matched population, the multivariate analyses showed that tumour invasion into adjacent organs/structures and non-utilisation of PORT were independent poor prognostic factors for CSS, whereas age ≥62 years,tumour invasion into adjacent organs/structures, and non-utilisation of PORT were independently associated with poorer OS. The subgroup analysis revealed that PORT improved CSS and OS in Masaoka-Koga stage III thymoma, but showed no OS benefit in Masaoka-Koga stage IIB thymoma.

CONCLUSION

Based on the SEER database, we found that PORT provides a significant survival benefit in Masaoka-Koga stage III thymoma with complete or incomplete resection. The role of PORT in thymoma requires further evaluation.

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.

The Prognostic Value of Postoperative Radiotherapy for Thymoma and Thymic Carcinoma: A Propensity-Matched Study Based on SEER Database

(1) Objectives: The effect of postoperative radiotherapy (PORT) for thymoma and thymic carcinoma remains controversial. This study aimed to investigate the prognostic value of PORT for thymoma and thymic carcinoma in a population-based registry. (2) Methods: This retrospective study used the Surveillance, Epidemiology, and End Results (SEER) database to identify patients diagnosed with thymoma and thymic carcinoma between 2010 and 2019. Propensity score matching was performed to adjust statistical influences between the PORT and non-PORT groups. (3) Results: A total of 2558 patients with thymoma (n = 2138) or thymic carcinoma (n = 420) were included. In the multivariate analysis, PORT was an independent prognostic factor for OS (overall survival; p < 0.001) and CSS (cancer-specific survival; p = 0.001) in thymoma and an independent prognostic factor for OS in thymic carcinoma (p = 0.018). Subgroup analyses revealed that PORT was beneficial to OS and CSS in patients with Masaoka-Koga stage IIB-IV thymoma (OS: IIB, p < 0.001; III-IV, p = 0.005; CSS: IIB, p = 0.015; III-IV, p = 0.002) and stage IIB thymic carcinoma (OS: p = 0.012; CSS: p = 0.029). (4) Conclusion: This propensity-matched analysis identified the prognostic value of PORT in thymoma and thymic carcinoma based on the SEER database. For patients with stage IIB-IV thymoma and stage IIB thymic carcinoma, PORT was associated with improved OS and CSS. A more positive attitude towards the use of PORT for nonlocalized thymoma and thymic carcinoma may be appropriate.

Nomogram predicts the prognosis of patients with thymic carcinoma: A population-based study using SEER data

BACKGROUND

Thymic carcinoma (TC) is a rare malignant tumor that can have a poor prognosis, and accurate prognostication prediction remains difficult. We aimed to develop a nomogram to predict overall survival (OS) and cancer-specific survival (CSS) based on a large cohort of patients.

METHODS

The Surveillance Epidemiology and End Results (SEER) database was searched to identify TC patients (1975-2016). Univariate and multivariable Cox regression analyses were used to identify predictors of OS and CSS, which were used to construct nomograms. The nomograms were evaluated using the concordance index (C-index), calibration curve, receiver operating characteristic curve, and decision curve analysis (DCA). Subgroup analysis was performed to identify high-risk patients.

RESULTS

The analysis identified six predictors of OS (Masaoka stage, surgical method, lymph node metastasis, liver metastasis, bone metastasis, and radiotherapy) and five predictors of CSS (Masaoka stage, surgical method, lymph node metastasis, tumor size, and brain metastasis), which were used to create nomograms for predicting three-year and five-year OS and CSS. The nomograms had reasonable C-index values (OS: 0.687 [training] and 0.674 [validation], CSS: 0.712 [training] and 0.739 [validation]). The DCA curve revealed that the nomograms were better for predicting OS and CSS, relative to the Masaoka staging system.

CONCLUSION

We developed nomograms using eight clinicopathological factors that predicted OS and CSS among TC patients. The nomograms performed better than the traditional Masaoka staging system and could identify high-risk patients. Based on the nomograms' performance, we believe they will be useful prognostication tools for TC patients.

Effect Evaluation of Subxiphoid and Intercostal Thymectomy: A Meta-Analysis and Systematic Review

Background

It still remains unclear whether subxiphoid video-assisted thoracoscopic surgery (SVATS) thymectomy is safe and reasonable. This meta-analysis aims at assessing the effectiveness and safety of SVATS for thymoma in comparison with that of intercostal video-assisted thoracoscopic surgery (IVATS) thymectomy.

Methods

All the relevant data systematically analyzed in this thesis were retrieved from PubMed, the Cochrane Library, web of science, EMBASE, and ClinicalTrials.gov. The time span for data retrieval was from the date of database establishment to March 2022. The outcome indicators include operation time, intraoperative blood loss, duration of postoperative drainage, postoperative hospital days, visual analogue scale (VAS) score on the day of operation, VAS score on postoperative day 3, and VAS score on postoperative day 7; postoperative complications were analyzed in our meta-analysis.

Results

In 13 studies of this paper, there were 1,198 cases included. Among them, 563 cases were treated by SVATS thymectomy and 635 cases by IVATS thymectomy. There was no significant difference in the operation time [113.38 vs. 119.91  min, 95% confidence interval (CI): −0.70–0.15, p = 0.20) and the incidence of intraoperative and postoperative complications (RR = 0.82, 95% CI: 0.58–1.15, p = 0.25) between SVATS thymectomy and IVATS thymectomy. However, SVATS thymectomy significantly reduced the amount of intraoperative blood loss (47.68 vs. 66.69  mL, SMD = −0.57, 95% CI: −0.95 to −0.18, p = 0.004), postoperative drainage days (2.12 vs. 2.72 days, SMD = −0.46, 95% CI: −0.74 to −0.18, p = 0.001), postoperative hospital stays (4.53 vs. 5.91 days, SMD = −0.64, 95% CI: −0.96 to −0.31, p = 0.0001), and VAS scores after the operation.

Discussion

SVATS thymectomy is safe and feasible, and the perioperative effect is better than IVATS thymectomy to a certain extent, which is worthy of popularization and further research.

Systematic Review Registration:https://www.crd.york.ac.uk/PROSPERO/

“Radiotherapy for Thymic Epithelial Tumors: What Is The Optimal Dose? A Systematic Review.”

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Thymic epithelial tumors(TETs) often require a multimodal approach, including RT.

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RT dose recommendations largely derive from old data, where 2D RT was widely used.

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This systematic review focused on the optimal dose for TETs with modern RT.

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5 eligible studies reporting dose response were analyzed and synthesized.

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Current guidelines remain valid, this work might be an eye-opener fostering new data.

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.

Prognostic impact of tumor volume in patients with complete resection of thymoma

Background

The impact of tumor volume on prognosis is unclear. We therefore investigated the correlation between tumor volume and prognosis in patients with complete resection of thymoma.

Methods

A total of 177 patients who underwent curative surgical resection for thymoma were retrospectively collected and reviewed. We performed a volumetric analysis of each case using the modified version of “Watchin GGO” and evaluated the relationship between tumor volume and recurrence.

Results

The median tumor size was 5.0 (range 0.5–15) cm, and the median tumor volume was 35.1 (range 0.265–881.0) cm³. The Pearson product–moment correlation coefficient was 0.658, suggesting a moderately strong connection between tumor volume and tumor size. To determine the impact of tumor volume on tumor recurrence, receiver operating characteristic curves of the recurrence and tumor volume were calculated. The area under the curve was 0.65 (95% confidence interval [CI]: 0.51–0.80), and the optimal cutoff level of the tumor volume for recurrence was 82.6 cm³, with a sensitivity and specificity of 0.64 (11/17) and 0.74 (119/160), respectively. Patients with tumors ≥82.6 cm³ had a significantly worse recurrence‐free survival than those with smaller tumors (p = 0.0122, hazard ratio: 2.99), with 5‐year recurrence rates of 74.9% (95% CI: 58.6%–86.3%) versus 88.9% (95% CI: 79.0%–94.4%).

Conclusion

The volume of completely resectable thymoma may be a useful prognostic indicator.

Occult pleural dissemination detected intraoperatively in patients with thymic tumors: a retrospective analysis

BACKGROUND

Thymic tumors usually present with adjacent organ invasion or pleural dissemination, but very few studies have reported on occult pleural dissemination detected intraoperatively. This study aimed to investigate the risk factors that can predict pleural dissemination preoperatively.

METHODS

Consecutive patients with thymic tumors who underwent surgery from January 2010 to January 2017 were reviewed. Only patients without pleural dissemination detected preoperatively were included in this study. Demographic, clinical, pathological, and survival data were collected for statistical analysis. Further analyses were performed to find the risk factors of occult pleural dissemination.

RESULTS

A total of 352 patients with thymic tumors were included in this study. Seven patients had pleural dissemination detected intraoperatively. All pleural dissemination cases were in clinical Masaoka-Koga stage III, and most underwent the video-assisted thoracoscopic surgery (VATS) approach (or VATS exploration). Univariate analysis showed that positive squamous cell carcinoma (SCC) antigen was the only predictor of pleural dissemination (p = 0.009). Tiny nodules close to the diaphragm were detected in the computed tomography scans of 1 case after reviewing the imaging data. Tumor recurrence occurred in 5 patients during follow-up. The disease-free survival rates were better in patients with a solitary nodule than those with multiple nodules (p = 0.019). No significant difference was detected in terms of disease-free survival rates between SCC antigen positive and SCC antigen negative patients.

CONCLUSIONS

Positive SCC antigen was the only detected risk factor for predicting pleural dissemination in thymic tumors preoperatively in this study. The VATS approach (including VATS exploration) is suggested for patients with clinical Masaoka-Koga stage III and SCC antigen positive thymic tumors, according to our experience.

Partial Versus Complete Thymectomy in Non-Myasthenic Patients With Thymoma: A Systematic Review and Meta-Analysis of Clinical Outcomes

The optimal extent of surgical resection for non-myasthenic patients with thymoma is controversial. The objective of this meta-analysis was to compare complete to partial thymectomy in non-myasthenic patients for oncological and postoperative clinical outcomes. We performed a PubMed and EMBASE search (from inception to January 2020) for English-language studies directly comparing partial to complete thymectomy for thymoma resection. Clinical endpoints studied included overall and disease-free survival, Masaoka and World Health Organization staging, adjuvant therapy, postoperative complications, postoperative drainage, length of hospital stay, thymoma-related deaths, postresection development of myasthenia gravis, incomplete resection, and recurrence. Random effects meta-analyses across all clinical endpoints was done. There was no statistically significant difference between the two approaches with regard to recurrence (odds ratio [OR], 1.22; 95% confidence interval [CI], 0.78-1.92), completeness of resection (OR, 1.17; 95% CI, 0.66-2.10), adjuvant therapy (OR, 0.71; 95% CI, 0.40-1.26), or thymoma-related deaths (OR, 0.76; 95% CI, 0.12-4.66). There was a statistically significant decrease in postoperative complications (OR, 0.61; 95% CI, 0.39-0.97), drainage (mean difference [MD], -0.99; 95% CI, -1.98 to -0.01), and length of hospital length (MD, -1.88; 95% CI, -3.39 to -0.36) with partial thymectomy. The evidence appeared to suggest that partial thymectomy is oncologically equivalent to complete thymectomy for non-myasthenic patients with early-stage thymoma. There is an additional advantage of reduced postoperative complications and decreased length of hospital stay with partial thymectomy.

Thymoma Staging: An Analysis of the Different Schemas

Over the last years, a number of changes has taken place in the evaluation of thymomas. More recently, the introduction of a TNM staging system in the assessment of thymic epithelial tumors, in general, has been put forward. Important to highlight is that this TNM system is not based on tumor size, and because of that shortcoming, it was in need to borrow most if not all of the information from the experience derived from other schemas that over the years have been tested with larger series of cases. Also important to recognize is that this TNM system is nothing new as previous authors in the past had already attempted to provide a TNM system for thymomas without much success. Therefore, it becomes important that those involved with the staging of thymomas become familiar with previous schemas as the TNM system provides a slight different spin in the T component, while the M component truly represents advance stages of previous schemas. More importantly is to also highlight that despite the specific anatomic structures addressed in the T or M assessment, there is little information in the most important aspect of any staging system-clear definitions of invasion and metastasis and the gross assessment of these tumors to provide an accurate staging. Capsular integrity still remains paramount in such assessment. A critical assessment of TNM system compared with previously proposed staging systems and whether there is a real advancement in applying it is discussed as well as the gross assessment of these tumors to highlight the importance of the staging protocol.

The International Thymic Malignancy Interest Group Classification of Thymoma Recurrence: Survival Analysis and Perspectives

INTRODUCTION

The International Thymic Malignancy Interest Group (ITMIG) classifies thymoma recurrences on the basis of the topographic location, but its effectiveness in prognosis prediction has not been well investigated yet. Aims of this study are to analyze survival outcome of patients surgically treated for thymoma recurrence according to the ITMIG recurrence classification and to investigate possible alternatives.

METHODS

From January 1, 1990, to January 7, 2017, data on 135 surgically treated patients for thymoma recurrence from three high-volume centers were collected and retrospectively analyzed. Patients were classified according to the ITMIG classification as local, regional, and distant. The ITMIG classification and alternative classifications were correlated to overall survival (OS).

RESULTS

According to the ITMIG classification, recurrence was local in 17 (12.5%), regional in 97 (71.8%), and distant in 21 (15.7%) patients, with single localization in 38 (28.2%) and multiple localizations in 97 (71.8%). The 5- and 10-year OS were 79.9% and 49.7% in local, 68.3% and 52.6% in regional, and 66.3% and 35.4% in distant recurrences, respectively, but differences were not statistically significant (p = 0.625). A significant difference in survival was present considering single versus multiple localizations: 5- and 10-year OS of 86.2% and 81.2% versus 61.3% and 31.5% (p = 0.005, hazard ratio = 7.22, 95% confidence interval: 0.147-0.740), respectively. Combining the localization number with the recurrence site, ITMIG locoregional single recurrence had a statistically significant better survival compared with patients with ITMIG locoregional multiple recurrence or ITMIG distant recurrence (p = 0.028). Similarly, a significant difference was present considering intrathoracic single versus intrathoracic multiple versus distant recurrence (p = 0.024).

CONCLUSIONS

The ITMIG classification for thymoma recurrence did not have significant survival differences comparing local, regional, and distant recurrences. Integrating this classification with the number of the localizations may improve its effectiveness in prognosis prediction.

Limited resection for early-stage thymoma: minimally invasive resection does not mean limited resection

Standard resection for patients with thymoma is resection of thymoma with total thymectomy (TTx) via median sternotomy. Hence, limited resection for thymoma means a lesser extent of resection of normal thymus compared with a standard procedure, i.e. resection of thymoma with partial thymectomy (PTx). In contrast, minimally invasive resection has been defined as resection of thymoma with TTx via a less-invasive approach. However, to date, few studies have precisely evaluated the differences in surgical and oncological outcomes among these three procedures. This report summarizes the differences among these three procedures with a review of studies (January 2000 to December 2020) focusing on the difference in surgical and oncological outcomes and presents current issues in the surgical management of thymoma. In this report, 16 studies were identified; 5 compared standard resection to limited resection, 9 compared standard resection to minimally invasive resection and 2 compared limited resection to minimally invasive resection. Most studies reported that the surgical and oncological outcomes of limited resection or minimally invasive resection were similar to those of standard resection in patients with early-stage thymoma. However, they did not include a sufficient follow-up period. Both limited resection and minimally invasive resection for early-stage thymoma might be reasonable treatment options. However, they are still promising modes of resection. Further studies with a long follow-up period are needed.

Thymic Carcinoma With Multiple Paraneoplastic Disorders

Thymic neoplasms are rare and may run an indolent course. Among them, thymic epithelial carcinoma is exceptional as it may be presented with extensive local invasion and distant metastases. There is a wide spectrum of autoimmune/paraneoplastic syndromes associated with thymic tumors including autoimmune diseases, some of which may precede the diagnosis of thymoma. This article describes a 37-year-old woman with metastatic malignant thymoma and a combination of manifestations from different organs. Vitiligo, Raynaud's phenomenon and anti-centromere antibodies were preceded while eosinophilia, interstitial lung disease, rash, thickening of the skin and asymptomatic cryoglobulinemia were diagnosed concomitantly with the neoplasm. We have reviewed the literature and found only twenty case reports with a cluster of three or more autoimmune/paraneoplastic syndromes in the same patient but none with this unique constellation of disorders. The diversity of thymoma's clinical presentation and laboratory/histological features may cause diagnostic dilemmas and therapeutic challenges.

Thymic Epithelial Neoplasms: Tumor-Node-Metastasis Staging

Thymic epithelial neoplasms are a group of malignant tumors that includes thymoma, thymic carcinoma, and thymic neuroendocrine tumors. Although several staging systems have been developed over the years for use with these cancers, they have been interpreted and implemented in a nonuniform manner. Recently, the International Association for the study of Lung Cancer and the International Thymic Malignancy Interest Group developed a tumor-node-metastasis staging system that has been universally accepted and correlates with patient survival and outcomes. Although pathologic staging is determined by histologic examination of the resected tumor, imaging plays an important role in clinical staging and is important for informing therapeutic decisions.

Management of bleeding complications during thymectomy by subxiphoid approach with double elevation of the sternum: a case report

Thymoma is the most common tumor of the anterior mediastinum and surgical resection for thymoma has been recommended as the principal treatment. Bleeding control remains as a challenging task under minimally invasive approach. Subxiphoid approach with double elevated of sternum was a novel method which might provide good surgical view and space for operating. In this study we reported a case of bleeding control with this approach after unexpected damage to innominate vein to address the advantage of bleeding control using this specific surgical approach. The case was a 66-year-old female patient with an anterior mediastinal mass incidentally detected during physical examination and was diagnosed with thymoma with a diameter of 5 cm. Injury to the joint of innominate vein and the vena cava occurred during a subxiphoid approach with double elevation of the sternum. It was well managed by controlling the bleeding site with Alice forceps and suture under thoracoscope view without conversion to median sternotomy. A 4-0 PROLENE line was used with an elbow needle holder under the thoracoscope to suture continuously. Intraoperative blood loss was 350 mL. The drainage tubes were removed on postoperative day (POD) 2, and the patient was discharged on POD 3. This case indicated that thymectomy by subxiphoid approach with double elevation of the sternum has more advantages when there is an emergency for bleeding during the operation compared with traditional intercostal approach or subxiphoid approach with carbon dioxide inflation.

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.

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.

Surgical management of thymic epithelial tumors

Resection is the mainstay of treatment for thymic epithelial tumors (TETs), with complete removal of the tumor and involved organs being the ultimate aim. The choice of surgical approach plays a major role in defining treatment success, and the optimal choice of method should thus provide an adequate surgical view to achieve complete tumor resection. While median sternotomy is considered the gold standard for access to the mediastinum, several minimally invasive approaches to thymectomy have been described, including video-assisted robotic-assisted thymectomy, although the oncological outcomes of that procedure remain unclear. A multimodal approach incorporating chemotherapy or chemoradiotherapy followed by extended surgery may improve resectability and outcomes for patients with advanced TETs. Surgical debulking is also reportedly acceptable for invasive thymoma because of its potential for achieving favorable outcomes. Re-resection is an acceptable option for patients with recurrent thymoma after initial resection, and repeat resection for recurrent pleural dissemination seems effective. Here, the literature on current clinical practices in the surgical management and treatment of TETs is reviewed.

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.

Does size matter? A national analysis of the utility of induction therapy for large thymomas

Background

Tumor size of 8 cm or greater is a risk factor for recurrence after thymoma resection, but the role of induction therapy for large thymomas is not well defined. This study tested the hypothesis that induction therapy for thymomas 8 cm and larger improves survival.

Methods

The use of induction therapy for patients treated with surgical resection for Masaoka stage I–III thymomas in the National Cancer Database between 2006–2013 was evaluated using logistic regression, Kaplan-Meier analysis, and Cox-proportional hazards methods.

Results

Of the 1,849 patients who met inclusion criteria, 582 (31.5%) had tumors ≥8 cm. Five-year survival was worse in patients with tumors ≥8 cm compared to smaller tumors [84.6% (95% CI: 81.2–88.1%) vs. 89.4% (95% CI: 87.2–91.7%), P=0.003]. Induction therapy was used in 166 (9.0%) patients overall and was more likely in patients with tumors ≥8 cm [adjusted odds ratio (AOR) 3.257, P<0.001]. Induction therapy was not associated with improved survival in the subset of patients with tumors ≥8 cm in either univariate [80.9% (95% CI: 72.6–90.1%) vs. 85.4% (95% CI: 81.8–89.3%), P=0.27] or multivariable analysis [hazard ratio (HR) 1.54, P=0.10]. Increasing age (HR 1.56/decade, P<0.001) and Masaoka stage III (HR 1.76, P=0.04) were associated with worse survival in patients with tumors ≥8 cm.

Conclusions

Survival after thymoma resection is worse for tumors 8 cm or larger compared to smaller tumors and is not improved by induction therapy. Size alone should not be a criterion for using induction therapy prior to thymoma resection.

Treatment Outcome and Prognostic Factors of Malignant Thymoma - A Single Institution Experience

Objective:

Our objectives are to investigate the clinicopathological features, treatment modalities, and prognostic and prognostic factors in order to estimate long-term outcomes for patients with thymoma and thymic carcinoma at our institution.

Methods:

We reviewed all patients diagnosed with thymic malignancies malignancies over a period of 38 years (from 1976 to 2014). Patients were identified using a single institution database at King Faisal Specialist Hospital and Research Center (KFSH and RC), Riyadh. Demographic data, clinical staging, histopathology classification, treatment approaches, and survival data were collected. Data Analysis was performed using both the Kaplan–Meier method and Cox proportional hazards modeling.

Results:

The fifty-six identified patients consists of 30 females (53.6%) and 26 males (46.4%). The median age at diagnosis was 39 years. About 37% of the patients were diagnosed with myasthenia gravis (MG). There was a significant association between the WHO histologic classification and the Masaoka stage (p= 0.018). The estimated 5-year overall survival rate was 88.6% for patients with thymic malignancies. The median survival time of thymoma and thymic carcinoma was 61 and 14 months, respectively. The univariate analysis suggested that histology (thymoma versus thymic carcinoma, p= 0.044) and Masaoka stage (II-III versus IV, p= 0.048) were independent prognostic factors affecting overall survival. Histology (p = 0.044) was found to be an independent predictor of overall survival.

Conclusion:

The findings of this study indicates that late Masaoka-Koga staging and histology types are significantly associated with extended overall survival. Similarly, surgical resection and multimodality treatments play a significant role in thymic malignancies neoplasms therapy strategies to prolong survival rates.

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.

The Role of Adjuvant Therapy in Advanced Thymic Carcinoma: A National Cancer Database Analysis

BACKGROUND

There is area of controversy and variability in the recommendation for the role of adjuvant therapy after R0 resection of a Masaoka stage IIB and III thymic carcinoma. This study investigated the role of adjuvant therapy in patients who had complete surgical resection for thymic carcinoma.

METHODS

Patients with stage IIB and III thymic carcinoma who underwent curative resection were queried and categorized according to Masaoka-Koga stage groups from the National Cancer Database. Patients were grouped by treatment status (surgery only or surgery followed by adjuvant therapy). Kaplan-Meier estimates of overall survival and univariate and multivariate Cox proportional hazards regression analyses were performed.

RESULTS

From 2004 to 2013, 632 surgical patients with stage IIB and III thymic carcinoma were selected for analysis. In stage IIB patients, the adjuvant therapy group had improved survival compared with the surgery only group (P = .01), although no survival difference was observed in patients who had R0 resection between the 2 groups (P = .59). In multivariate analysis, age (P < .001) and grade III and IV (P = .02) negatively impacted survival; the adjuvant therapy improved survival (P < .02). For stage III cancer, the adjuvant therapy group had improved survival compared with the OS group regardless of margin status. In multivariate analysis, tumor size exceeding 70 mm (P = .02) and positive margin (P < .01) negatively affected survival; adjuvant therapy improved survival (P < .01).

CONCLUSIONS

Adjuvant therapy showed no benefit in patients with stage IIB cancer who had R0 resection. Use of adjuvant therapy should be strongly considered for stage IIB cancer patients with positive margins and all stage III thymic cancer patients.

Thymoma appearing 9 years after the resection of squamous cell carcinoma of the lip: A case report of triple primary tumors and literature review

The occurrence of second primary tumor (SPT)following malignancy treatment is common. In patients with head and neck (H&N) cancer, SPTs principally occur in the H&N region, lungs or esophagus. Therefore, patient follow-up after cancer treatment is important in order to detect recurrence, metastasis and new primary tumors. However, no standard guidelines on lifelong follow-up imaging are available. Herein, we report a patient who presented with three metachronous primary tumors-squamous cell carcinoma (SCC) of the tongue, SCC of the lip and type A thymoma. The third tumor was incidentally detected during follow-up using contrast-enhanced computed tomography (CT) 9 years following resection of the second tumor. To the best of our knowledge, this specific combination of metachronous tumors has not yet been reported. Based on the literature review, we observed that thymoma occurs following H&N cancer treatment. Therefore, to ensure that the presence of subsequent thymomas is not overlooked, we suggest regular lifelong follow-up using contrast-enhanced CT in patients who had previously been diagnosed with H&N cancer. The literature review revealed that thymomas occur in patients with H&N cancer and should be detected at the earliest convenience.

Multilobulated thymoma with an acute angle: a new predictor of lung invasion

OBJECTIVE

Imaging features of thymomas such as lobulation, infiltration into lung, and adjacent lung abnormality have been associated with lung invasion but are unreliable. The goal of this study was to develop a more objective and reproducible method for predicting lung invasion by thymomas.

SUBJECTS AND METHODS

Fifty-four thymomas resected from 2007 to 2017 were included for analysis. Pre-operative CT scans for these thymomas were reviewed, and multiple features were evaluated, including the interface of each thymoma with the adjacent lung. A multilobulated thymoma with at least one acute angle between lobulations was considered suspicious for lung invasion. Two blinded radiologists then tested this hypothesis by reviewing all 54 CT scans and using this single criterion to predict lung invasion.

RESULTS

Twelve thymomas invaded the lung. All lung-invasive thymomas were multilobulated. Twenty-nine thymomas had a multilobulated interface with the lung. Multilobulated thymomas were more likely to invade the lung than thymomas with a single lobulation or no lobulation (p = 0.0008). Using the criterion of multilobulation with at least one acute angle between lobulations to predict lung invasion, the two readers achieved a sensitivity of 67-83%, specificity of 93-98%, positive predictive value of 77-89%, and negative predicted value of 91-95%. Nine lung-invasive thymomas also invaded mediastinal structures or disseminated to the pleura.

CONCLUSIONS

A multilobulated thymoma with at least one acute angle between lobulations predicts lung invasion with a high degree of accuracy. When lung invasion is suspected, the findings are indicative of a locally aggressive tumor, and the pleura and mediastinal structures should also be closely inspected for invasion.

KEY POINTS

• A multilobulated thymoma with at least one acute angle between lobulations is predictive of lung invasion. • Coronal and sagittal reformations and thin sections are helpful in challenging cases. • Lung invasion indicates a locally aggressive tumor, and the pleura and other mediastinal structures should also be closely inspected for invasion.

Volumetric analysis of the thymic epithelial tumors: correlation of tumor volume with the WHO classification and Masaoka staging

BACKGROUND

The purpose of our study was to investigate the correlation between tumor volume (TV) and each subtype of thymic epithelial tumors (TETs) based on the World Health Organization (WHO) classification and Masaoka staging.

METHODS

Sixty-one consecutive patients (45 thymomas and 16 thymic carcinomas) were studied. All were classified according to Masaoka staging: 31 non-invasive TETs (stage I) and 30 invasive TETs (8 stage II, 11 stage III, 3 stage IVa, and 8 stage IVb). TV on computed tomography (CT) were semi-automatically calculated using our software. The correlation of TV with each WHO subtype and Masaoka staging was analyzed using Mann-Whitney U and Scheffe's F test.

RESULTS

Thymic carcinoma (mean ± SD, 117.5±143.6 cm3) was significantly larger than thymoma (53.4±78.4 cm3) (P=0.0016). Stage IVb tumor (190.8±156.8 cm3) was significantly larger than stage I (33.1±42.6 cm3) (P<0.05). Invasive TETs were significantly larger than non-invasive TETs (P=0.0016). TV >54.3 cm3 indicated invasive TETs.

CONCLUSIONS

TV of invasive TETs may be larger at the time of initial presentation. TV >54.3 cm3 indicates invasive TETs.

A Phase II Study of Partial and Subtotal Thymectomy for Thymoma (JART02)

BACKGROUND

We believe the merit of preservation of a part of the thymus following surgery for thymoma. We evaluated the efficacy of partial or subtotal thymectomy for early-stage thymoma in the prospective study.

METHODS

The Japanese Association for Research on the Thymus conducted a multiple institutional study of thymectomy for thymoma localized in the thymus without total thymectomy. Patients without autoimmune disease who had an anterior mediastinal tumor that had been clinically diagnosed as an early-stage thymoma were enrolled in the study. Patients who were positive for anti-acetylcholine receptor antibodies were excluded.

RESULTS

Sixty-three patients were enrolled preoperatively; 27 patients were judged as being inappropriate based on the other thymic pathologies or tumor invasion. The remaining 36 cases were diagnosed as early-staged thymoma and analyzed. The mean age of the patients was 61 years. The mean maximal tumor diameter in the resected specimens was 3.6 cm. The most common pathological types of thymoma were AB (n = 10) and B1 (n = 10). The Masaoka stages were classified as stage I (n = 22) and II (n = 14). The mean observation period was 63 months. Two patients died due to respiratory dysfunction, which was not related to thymoma. One hundred percent of the patients remained recurrence-free.

CONCLUSIONS

This prospective study suggested the efficacy of partial or subtotal thymectomy for early-stage thymoma in patients without any apparent evidence of autoimmune disease. We can preserve a part of the thymus even following surgery for thymoma to prepare the possible second malignancies or diseases in future.

Thoracoscopic Thymectomy Using a Subxiphoid Approach for Anterior Mediastinal Tumors

PURPOSE

Video-assisted thoracic surgery (VATS) techniques have been widely used for resection of mediastinal tumors. This study investigated the usefulness of the subxiphoid approach in thoracoscopic thymectomy.

METHODS

In all, 36 patients with anterior mediastinal tumor underwent thymectomy using the subxiphoid approach in two Japanese institutions. These patients were retrospectively reviewed and analyzed.

RESULTS

There were 16 females and 20 males with a mean age of 57 years. Five patients underwent partial thymectomy (PT), 27 underwent total or subtotal thymectomy, and 4 underwent thymectomy with combined resection (CR) of the surrounding organs or tissues. The mean maximum tumor diameter, amount of resected tissue, and blood loss were 4.1 cm, 72.5 g, and 20.6 g, respectively. More than half of tumors were diagnosed as thymoma (n = 19). The operation time was prolonged with a greater volume of thymectomy. The duration of chest tube drainage and postoperative stay were 1.7 ± 1.0 days and 5.9 ± 7.6 days, respectively. Four patients suffered intraoperative and postoperative complications, as follows: bleeding of the innominate vein, bleeding of the internal thoracic vein, crisis of myasthenia gravis (MG), pericarditis, and phrenic nerve paralysis. There were no mortalities after surgery.

CONCLUSION

Subxiphoid thoracoscopic thymectomy might be a safe and useful approach for mediastinal tumors.

The Subxiphoid Approach Leads to Less Invasive Thoracoscopic Thymectomy Than the Lateral Approach

OBJECTIVE

Video-assisted thoracic surgery (VATS) is widely used in thoracic surgery. This study investigated the usefulness of the subxiphoid approach in thymectomy using VATS techniques.

METHODS

Sixty operations were performed using the lateral approach (n = 46) and subxiphoid approach (n = 14). Using the lateral approach, 39 partial thymectomies (PT), 5 total or subtotal thymectomies (TT), and 2 total or subtotal thymectomies with combined resection of the surrounding organs (or tissues) (CR) were performed. Using the subxiphoid approach, 11 TT and 3 CR were performed.

RESULTS

There were 33 females and 27 males, with a mean age of 55 years. The mean maximum tumor diameter was 4.0 cm. The operation time was prolonged according to the volume of thymectomy (PT: 119, TT: 234, CR: 347 min). Additionally, the intraoperative blood loss increased according to the volume of thymectomy (PT: 29, TT: 47, CR: 345 g). To compare the invasiveness of both approaches, we compared 16 TT operations. In the group using the subxiphoid approach, the operation time became shorter (158 vs. 392 min), and the blood loss decreased (5 vs. 135 g) compared with the lateral approach. Regarding laboratory data, white blood cell counts on postoperative day 1 (1POD) (8200 vs. 10,300/μl) and CRP on 1POD and 3POD (2.8 and 2.8 vs. 7.9 and 10.2 mg/dl, respectively) decreased in the subxiphoid approach compared with the lateral approach.

CONCLUSIONS

The subxiphoid approach leads to a less invasive operation for anterior mediastinal tumors and extends the indications for VATS for invasive anterior mediastinal tumors.

Is thymomectomy sufficient for non-myasthenic early stage thymoma patients? A retrospective, single center experience

Background

Thymic complete resection is considered the standard treatment for all thymic tumors; however, the ideal resection for non‐myasthenic early stage thymic tumors has not yet been determined. We conducted a retrospective study to examine this unique scenario.

Methods

We retrospectively analyzed the data of 118 early stage thymoma patients who underwent thymectomy (TM) or thymomectomy (TMM) with curative intent between January 2003 and December 2013 at our institution. Patients with myasthenia, thymic carcinomas, tumors with undetermined histology, and more advanced stage thymoma patients were excluded. We compared overall survival (OS) and disease‐free survival (DFS) according to the extent of thymic resection, tumor staging, and size.

Results

One hundred and eighteen patients were staged as early thymoma. TM was performed in 43 (35.6%) patients and TMM in 75 (64.4%). Forty‐nine (65.3%) patients with a tumor ≤ 3 cm underwent TMM, and 9 (20.9%) TM. Twenty‐six (34.7%) patients with a tumor > 3 cm underwent TMM, and 34 (79.1%) TM. Seventy‐four patients were categorized as stage I: 57 (76%) underwent TMM and 17 (39.5%) TM. Forty‐four patients were categorized as stage II: 18 (24%) underwent TMM and 26 (60.5%) TM. There was no statistically significant difference in recurrence between the groups (P = 0.250).

Conclusion

No difference in the rate of recurrence was observed in early stage non‐myasthenic patients following thymic resection and Masaoka–Koga staging. However, TM is considered a better option for early stage thymoma patients with tumors > 3 cm.

Could thymomectomy be a reasonable option for non-myasthenic thymoma patients?

Background

Complete resection is the mainstay of treatment for thymoma, but few studies have investigated the extent of resection on normal thymus. Extended thymectomy is considered the treatment of choice for myasthenic patients with thymoma, while the optimal therapy for non-myasthenic patients is still a matter of debate. The aim of this retrospective study was to compare extended thymectomy vs. thymomectomy in non-myasthenic thymoma patients for (I) oncological outcome, (II) multicentric thymoma occurrence and (III) postoperative myasthenia gravis (MG) development.

Methods

A retrospective comparative study was conducted on 92 non-myasthenic patients with completely resected thymoma, according to the extent of resection: extended thymectomy (70 patients) vs. R0-mediastinal thymomectomy (22 patients). Clinical and pathological characteristics, oncological outcome and postoperative MG occurrence were compared between the two study groups.

Results

We did not observe any significant differences in gender, age, symptomology, preoperative chemotherapy, histology, tumour size, adjuvant therapy or complications. There were no recorded postoperative mortalities. Stage distribution was different between the two groups: similar percentages of early stage thymoma for both groups were present, but there was a prevalence of stage III for extended thymectomy and stage IV for thymomectomy (P<0.01). At a median follow-up of 77.4 months (range 1-255 months), no statistically significant differences were recorded in local recurrence (P=0.396), thymoma related deaths (P=0.504), multicentric thymoma occurrence (P=0.742) and postoperative MG development (P=0.343). A high preoperative anti-acetylcholine receptor antibodies (ARAb) serum titer assay was statistically correlated with postoperative MG occurrence (r=0.49, P<0.05).

Conclusions

Thymomectomy appears to be a valid treatment option for non-myasthenic thymoma patients, as this procedure was associated to the same 5-year oncological results, compared to extended thymectomy, for both stage I-II small thymomas and patients with giant unilateral masses, as well as advanced diseases. Moreover, thymomectomy was not associated to an increased rate of postoperative MG.

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.

Adjuvant Radiotherapy for Stages II and III Resected Thymoma: A Single-institutional Experience

INTRODUCTION

The role of adjuvant radiation for Masaoka stages II and III thymoma remains controversial. The aim of this study was to evaluate the clinical benefit of radiation therapy for resected stages II and III thymoma patients.

METHODS

We retrospectively reviewed the medical records of 175 thymoma patients treated from July 1996 to January 2013 at University of Washington Medical Center; 88 patients with adequate follow-up and who met histologic criteria were included. We evaluated progression-free survival (PFS) and overall survival (OS), and compared these outcomes in patients treated by surgery (S) alone versus surgery plus radiotherapy (S+RT). Cox regression models and log-rank tests were used to compare PFS and OS for S versus S+RT, and they were further assessed by margin-positive versus margin-negative subgroups using Kaplan-Meier curves.

RESULTS

Among the 88 thymoma patients, 22 were stage II and 18 were stage III. For all stages II and III patients, adjuvant radiation was not identified as a significant predictor for PFS (P=0.95) or OS (P=0.63). A positive surgical margin predicted for a worse OS (hazard ratio=7.1; P=0.004). Further investigation revealed for resection margin-positive patients; S+RT had higher OS than S alone (P=0.006).

CONCLUSIONS

For stages II and III thymoma, postoperative adjuvant radiation was not associated with statistically significant differences in PFS or OS in this study. Our results indicated a potential OS benefit of adjuvant RT in patients with positive resection margins, and therefore may be considered in this patient population.

Thoracoscopic thymectomy is a feasible and less invasive alternative for the surgical treatment of large thymomas

OBJECTIVES

Thoracoscopic surgery is widely used for the surgical treatment of thymoma. However, large-sized thymomas are typically treated using open surgery. This study evaluated the feasibility of performing thoracoscopic thymectomy (TT) for thymoma ≥50 mm.

METHODS

A retrospective review was conducted on 135 patients who underwent TT or open thymectomy (OT) for Masaoka stage I-IVa thymoma between 1996 and 2014.

RESULTS

Patients were first divided into two groups based on thymoma size: thymoma ≥50 mm and thymoma <50 mm groups. There was no significant difference in the 5-year disease-free survival (DFS) between the groups ( P  = 0.5352). Patients in the thymoma ≥50 mm group were further subdivided into TT and OT groups. The length of postoperative hospital stay was significantly shorter in the TT group than in the OT group (5 vs 14 days, P  < 0.0001), with significantly fewer postoperative complications (6 patients vs 14 patients, P  = 0.0008). There was no significant difference in the 5-year DFS between patients with thymoma ≥50 mm in the TT and OT groups ( P  = 0.3501). Finally, patients undergoing TT were further subdivided into thymoma ≥50 mm and thymoma <50 mm groups and, no significant difference in the 5-year DFS was found between these groups ( P  = 0.6661). Masaoka stages III-IV, but not thymoma size, were an independent prognostic factor for DFS.

CONCLUSIONS

These results demonstrate the decreased invasiveness and feasibility of TT for large-sized thymomas.

[Preoperative Induction Therapy for Locally Advanced Thymic Tumors: A Retrospective Analysis Using the ChART Database]

背景与目的

探讨术前诱导治疗在胸腺瘤中的应用及其对局部进展期胸腺瘤预后的影响。

方法

收集中国胸腺肿瘤协作组（Chinese Alliance of Research for Thymomas, ChART）1994年1月1日至2012年12月31日回顾性数据库中局部进展期胸腺瘤（Masaoka-Koga分期为Ⅲ期-Ⅳa期）病例。分为诱导治疗组和直接手术组，对比分析两组的R0切除率、5年复发率及5年生存率等指标。诱导治疗组术后分期为Masaoka-Koga Ⅰ期-Ⅱ期的病例视为诱导治疗后降期。为更加精确评估诱导治疗效果，在剔除术后Ⅳ期病例的基础上，再次将诱导治疗组术后Masaoka-Koga Ⅰ期-Ⅲ期的病例与直接手术组Masaoka-Koga Ⅲ期的病例进行对比分析。

结果

ChART回顾性数据库1, 713例有效病例中，局部进展期胸腺瘤706例，仅68例（4%）作了术前诱导治疗，R0切除率为67.6%，5年复发率为44.9%，5年与10年生存率分别为49.7%和19.9%。其中17例诱导治疗后达到降期，降期亚组中胸腺瘤的比例高于胸腺癌（38.7% vs 13.9%, P=0.02）；与未降期亚组相比，降期亚组获得更高的5年生存率（93.8% vs 35.6%, P=0.013）。剔除术后Ⅳ期的病例后，直接手术组和诱导治疗组R0切除率接近（76.4% vs 73.3%, P=0.63），但5年生存率差异明显（85.2% vs 68.1%, P < 0.001），对于降期亚组，5年生存率优于直接手术组（93.8% vs 85.2%, P=0.438），未降期亚组5年生存率仅35.6%，明显差于降期亚组和直接手术组（P < 0.001）。

结论

术前诱导治疗目前尚未在局部进展期胸腺瘤中广泛应用，但ChART的回顾性数据研究显示通过有效的术前诱导治疗可以使难以彻底切除的病例降期后增加R0切除的机会，从而延长生存，特别是胸腺瘤的病例。这一初步结果将有助于未来的研究。

Surgical and oncological outcomes of thoracoscopic thymectomy for thymoma

Thymoma remains the most common primary anterior mediastinal neoplasm. Surgical resection remains central to the treatment of thymoma, with thoracoscopic thymectomy (TT) being increasingly performed. This present review article aimed to summarize current studies comparing TT and open thymectomy (OT). Recently, most patients with Masaoka stage I-II thymoma have been receiving TT. This procedure is associated with a significantly shorter post-operative hospital stay, decreased intraoperative blood loss, and fewer complications compared with OT. Recurrence rates of thymoma after TT range from 0% to 6.7%, and the 5-year disease-free survival (DFS) ranges from 83.3% to 96%. The oncological outcomes of TT are comparable to that of OT. Masaoka stage and the World Health Organization (WHO) type classification are valuable predictors of the prognosis of thymoma; hence, the optimal treatment for thymoma should be performed according to these two. TT is less invasive, with equivalent oncological outcomes, when compared with the OT. Minimally invasive surgery including TT for stage I-II thymomas is becoming the mainstay of therapy.