Adjuvant radiotherapy for thymic epithelial tumors: a systematic review and meta-analysis

Postoperative radiotherapy results in 192 epithelial thymic tumours patients with 10 years of follow-up

PURPOSE

To assess the prognostic factors and patterns of failure of patients consecutively treated with surgery and postoperative radiation therapy (PORT) for thymic epithelial tumours (TET).

PATIENTS AND METHODS

Data from 192 TET patients who were operated and received PORT at a single centre from 1990 to 2019 was retrospectively analysed.

RESULTS

Most patients had thymoma (77 %, B247%), were classified Masaoka-Koga stage III (35 %) or IV (32 %) and had a R0 (75 %) resection. Radiotherapy was delivered at a median dose of 50.4 Gy (range, 42-66 Gy; ≥ 60 Gy in 17 %), 63 (33 %) patients were treated by intensity-modulated radiation therapy and elective nodal radiotherapy was used for 37 %. At a median follow-up of 10.9 years, the 10-year overall survival (OS) and progression-free survival (PFS) rates were 62 % (95 % CI: 54-70 %) and 47 % (95 % CI: 39-55 %), respectively. Locoregional recurrence (LRR) occurred in 72/192 (38 %) patients, distributed as 6 local, 45 regional and 21 both local and regional. LRR were mainly located to the pleura: 66/72 (92 %) and 16/72 (22 %; 16/192 in total, 8 %) were in-field. Distant relapse (DR) were observed in 30 patients (16 %), resulting in 10-year locoregional (LRC) and distant control rates of 58 % (95 % CI: 50-66 %) and 82 % (95 % CI: 77-88 %), respectively. In the multivariate analysis, Masaoka-Koga stage (HR [hazard ratio]: 1.9; p = 0.001), thymic carcinomas/neuroendocrine tumours (TC) (HR: 1.6; p = 0.045) and ECOG PS > 1 (HR: 1.9; p = 0.02) correlated with poorer OS. Higher Masaoka-Koga stage (HR: 2.6; p < 0.001) associated with a decreased LRC but not R1 status (HR: 1.2; p = 0.5) or WHO histology classification. TC (HR: 3.4; p < 0.001) and a younger age (HR: 2.5; p = 0.02) correlated with DR.

CONCLUSION

Approximately one-third of the TET in our study experienced a LRR, mainly to the pleura, and 8% in total were in-field. The place of radiotherapy should be better defined in higher risk thymoma patients within prospective randomized studies.

Role of radiotherapy in the management of rare solid thoracic tumors of the adults

Thoracic tumors include more than one hundred histopathological subtypes. Rare thoracic malignancies can be defined as representing less than 1% of all thoracic tumors. The European Rare Cancer Surveillance Project (RARECARE) identified rarity as an incidence less than 6 for 100,000 people, with significant difference of prevalence between them. Modalities of treatment for these pathologies include surgery, radiotherapy, and systemic therapies. In this article, we aim to discuss role and techniques of radiotherapy in management of rare solid thoracic tumors in adults, focusing on different anatomical locations such as lung parenchyma, mediastinum, vessels, chest wall and pleural cavity.

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.

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.

Thymic tumours and their special features

Thymic tumours are rare thoracic malignancies, that may be aggressive and difficult to treat. The pillars of the management include pathological review, consideration of differential diagnoses, staging and multidisciplinary discussion. Assessment of resectability is key to drive the treatment sequencing. Association with autoimmune diseases, especially myasthenia gravis, is observed, which impacts the oncological management. Networks are being built at the national and international levels. This article provides an overview of the most recent findings in the diagnosis, staging, histology, and management strategies of thymic tumours.

Thymic tumours are rare and heterogeneous tumours. Management is based on multidisciplinary discussion and networking.https://bit.ly/3kYAZ7u

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.

Invasive thymoma - Which patients benefit from post-operative radiotherapy?

BACKGROUND

The aim of this study is to identify patients with thymoma who should receive post-operative radiotherapy.

METHODS

The Surveillance, Epidemiology, and End Results database was queried for stage IIB-IV thymoma patients diagnosed during 1988-2015. We analyzed the prognostic implications of various clinical-pathological factors by comparing the outcomes of those who received surgery with and without post-operative radiotherapy.

RESULTS

A total of 1120 patients were identified; 62% received post-operative radiotherapy and 38% underwent surgery alone. In a propensity-matched cohort of 812 patients, no survival difference was seen in World Health Organization A, AB, B1, B2, or B3 tumors with the addition of post-operative radiotherapy to surgery (p>0.05). Post-operative radiotherapy also did not improve survival over surgery alone for tumors ≥ or < less than the 4 cm, 7 cm, 10 cm, and 13 cm cutoffs, all p>0.05. Post-operative radiotherapy was an independent, positive prognostic indicator only in the subgroup with stage III disease and in those receiving chemotherapy in addition to post-operative radiotherapy, both p<0.05.

CONCLUSIONS

Patients with stage III thymoma are most likely to benefit from the addition of post-operative radiotherapy to surgical treatments. Tumor size or World Health Organization histology alone should not be criteria for determining the need for post-operative radiotherapy in locally advanced thymoma. Masaoka-Koga stage, which has traditionally been used to help make such decisions, appears to be the most reliable determinant of the use of post-operative radiotherapy.

GOECP/SEOR radiotherapy guidelines for thymic epithelial tumours

Thymic epithelial tumours (TET) are rare, heterogeneous neoplasms that range from resectable indolent tumours to aggressive thymic carcinomas with a strong tendency to metastasize. The pathological diagnosis is complex, in part due to the existence of several different classification systems. The evidence base for the management of TETs is scant and mainly based on non-randomised studies and retrospective series. Consequently, the clinical management of TETs tends to be highly heterogenous, which makes it difficult to improve the evidence level. The role of technological advances in the field of radiotherapy and new systemic therapies in the treatment of TETs has received little attention to date. In the present clinical guidelines, developed by the GOECP/SEOR, we review recent developments in the diagnosis and classification of TETs. We also present a consensus-based therapeutic strategy for each disease stage that takes into consideration the best available evidence. These guidelines focus primarily on the role of radiotherapy, including recent advances, in the management of TETs. The main aim of this document is to promote the standardisation of clinical practice and lay the foundations for future studies to clarify the main unresolved questions related to the optimal management of TET.

Radiotherapy for thymic epithelial tumours: a review

Thymic epithelial tumours (TETs) represent a rare disease, yet they are the most common tumours of the anterior mediastinum. Due to the rare occurrence of TETs, evidence on optimal treatment is limited. Surgery is the treatment of choice in the management of TETs, while the role of postoperative radiotherapy (PORT) remains unresolved. PORT remains debated for thymomas, especially in completely resected stage II tumours, for which PORT may be more likely to benefit in the presence of aggressive histology (WHO subtype B2, B3) or extensive transcapsular invasion (Masaoka-Koga stage IIB). For stage III thymoma, evidence suggests an overall survival (OS) benefit for PORT after complete resection. For incompletely resected thymomas stage II or higher PORT is recommended. Thymic carcinomas at any stage with positive resection margins should be offered PORT. Radiotherapy plays an important role in the management of unresectable locally advanced TETs. Induction therapy (chemotherapy or chemoradiation) followed by surgery may be useful for locally advanced thymic malignancies initially considered as unresectable. Chemotherapy only is offered in patients with unresectable, metastatic tumours in palliative intent, checkpoint inhibitors may be promising for refractory diseases. Due to the lack of high-level evidence and the importance of a multidisciplinary approach, TETs should be discussed within a multidisciplinary team and the final recommendation should reflect individual patient preferences.

The safety and efficacy of Cyberknife® for thymic malignancy

PURPOSE

To evaluate the safety and efficacy of Cyberknife® (CK) for the treatment of primary or recurring thymic tumours.

MATERIALS AND METHODS

We retrospectively reviewed 12 patients (16 tumour lesions) with primary or recurring thymic tumours who were treated with CK between March 2008 and October 2017. Their data was stored in prospectively collected database. Kaplan-Meier method was used to calculate survival curves.

RESULTS

Five patients (41.7%), who had inoperable disease or refused surgery, were treated with CK initially, and 7 patients (58.3%) were treated with CK when they had recurrence diseases. The disease sites treated with CK were primary tumour site (5), regional lymph nodes (4), tumour bed (3), chest wall (2), pleura (1), and bone (1). The median target volume was 43.8 cm³ (range, 13.1-302.5cm³) for the 16 tumour lesions. The median follow-up time was 69.3 months (range, 9.7-124.8 months). The median survival time was 48.2 months, and the 5-year and 10-year OS rates were 68.2% and 45.5%, respectively. A high response rate for the tumour lesions irradiated with CK was obtained. Only one patient (8%) experienced in-field recurrence, and the 5-year local recurrence free survival was 90.9%. A case indicated that CK may induce the abscopal effect, which provides the potential to combine CK and immunotherapy. No severe radiation related toxicities were observed, and no treatment related death occurred.

CONCLUSION

CK treatment resulted in good outcomes, particularly local control, with minimal side effects, in highly selected patients with primary and recurring thymic tumours. More studies with larger sample are needed.

RADIORYTHMIC: Phase III, Opened, Randomized Study of Postoperative Radiotherapy Versus Surveillance in Stage IIb/III of Masaoka Koga Thymoma after Complete Surgical Resection

INTRODUCTION

Thymomas are rare intrathoracic malignancies that may be aggressive and difficult to treat. Knowledge and level of evidence for treatment strategies are mainly based on retrospective studies or expert opinion. Currently there is no strong evidence that postoperative radiotherapy after complete resection of localized thymoma is associated with survival benefit in patients. RADIORYTHMIC is a phase III, randomized trial aiming at comparing postoperative radiotherapy versus surveillance after complete resection of Masaoka-Koga stage IIb/III thymoma. Systematic central pathologic review will be performed before patient enrollment as per the RYTHMIC network pathway.

PATIENTS AND METHODS

Three hundred fourteen patients will be included; randomization 1:1 will attribute either postoperative radiotherapy (50-54 Gy to the mediastinum using intensity-modulated radiation therapy or proton beam therapy) or surveillance. Stratification criteria include histologic grading (thymoma type A, AB, B1 vs B2, B3), stage, and delivery of preoperative chemotherapy. Patient recruitment will be mainly made through the French RYTHMIC network of 15 expert centers participating in a nationwide multidisciplinary tumor board. Follow-up will last 7 years. The primary endpoint is recurrence-free survival. Secondary objectives include overall survival, assessment of acute and late toxicities, and analysis of prognostic and predictive biomarkers.

RESULTS

The first patient will be enrolled in January 2021, with results expected in 2028.

Postoperative Radiotherapy for Completely Resected Masaoka/Masaoka-Koga Stage II/III Thymoma Improves Overall Survival: An Updated Meta-Analysis of 4746 Patients

INTRODUCTION

Our systematic review and meta-analysis aimed to evaluate the effect of postoperative radiotherapy (PORT) on completely resected Masaoka/Masaoka-Koga (M/MK) stage II/III thymomas.

METHODS

We systematically searched four online databases and included studies that compared surgery alone versus surgery plus a PORT for completely resected M/MK stage II/III thymoma. The multivariate-adjusted hazard ratios (HRs) of overall survival (OS) and disease-free survival were evaluated as the primary and secondary end points, respectively. We performed a subgroup analysis for OS with respect to M/MK stage II, III, and inseparable II/III cases. A generic inverse variance meta-analysis using a random model was conducted.

RESULTS

Five studies including 4746 patients (among them, 2408 patients received PORT) met our selection criteria. A meta-analysis of these five studies revealed that PORT was associated with a significantly better OS (HR = 0.68, 95% confidence interval [CI]: 0.57-0.83, p < 0.001, I² = 0%, p for heterogeneity = 0.97). Subgroup analyses for M/MK stage II disease (HR = 0.63, 95% CI: 0.44-0.91, p = 0.01, I² = 0%, p for heterogeneity = 0.80) and M/MK stage III disease (HR = 0.72, 95% CI: 0.55-0.95, p = 0.02, I² = 0%, p for heterogeneity = 0.84) revealed similar results. PORT was not associated with an improved disease-free survival (HR = 0.96, 95% CI: 0.70-1.33, p = 0.83, I² = 0%, p for heterogeneity = 0.72).

CONCLUSIONS

Currently available evidence from observational studies suggests PORT for patients with completely resected M/MK stage II/III thymoma. A randomized trial is warranted.

Multimodality approach in treatment of thymic tumors

Thymic tumors are rare neoplasms showing important clinical and pathologic polymorphisms ranging from low-mitotic encapsulated tumors to a highly aggressive and disseminating one. Complete resection of the tumor with surrounding fatty and mediastinal tissue is of paramount importance and provides good prognosis. Diagnosis of the tumor, radiologic evaluation and implementation of multimodal treatment including preoperative chemotherapy, radiotherapy, postoperative radiotherapy, adjuvant chemotherapy or radiotherapy are important components of the treatment strategy. Some of the stage III tumors can be resected without additional treatment, however, there is a good evidence to support administering preoperative and postoperative chemotherapy and postoperative radiotherapy in these patients providing higher complete resection rate and better survival. For stage IVA thymomas, surgery alone should not be considered as an effective approach and these tumors are considered as unresectable. Chemo/radiotherapy can be administered to those patients. Of those, postoperative chemotherapy and radiotherapy should be considered if these patients who were deemed to be previously unresectable become resectable. The combined modality treatment should provide prevention of locoregional and intrathoracic recurrence and eventually long-term survival with cure. New targeted therapies including agents against PI3K, CDK, and immune checkpoint PD-1/PD-L1 may lead to higher response rates with less toxicity.

The role of postoperative radiotherapy in stage II and III thymoma: a Korean multicenter database study

Background

Complete resection is a standard treatment for patients with Masaoka-Koga stages II and III thymoma, however the role of postoperative radiotherapy (PORT) is controversial. We analyzed data collected from 4 Korean hospitals to determine the effectiveness of PORT in stage II and III thymoma patients.

Methods

Between January 2000 and December 2013, 1,663 patients underwent surgery for thymic tumors at the 4 hospitals. Among them, 668 patients (527 with stage II and 141 with stage III) were investigated, among whom, 443 received PORT (335 with stage II and 108 with stage III). Propensity score matching (PSM) was performed, and 404 patients (346 with stage II and 58 with stage III) were selected.

Results

Perioperative characteristics were similar in the PORT and non-PORT groups after PSM. On survival analysis of stage II patients, the PORT and non-PORT groups showed no difference in either 5-year recurrence-free survival (RFS) (96.3% vs. 96.6%, P=0.622) or 5-year overall survival (OS) (94.6% vs. 93.8%, P=0.839). However, among stage III patients, the PORT group showed significantly better 5-year RFS (75.7% vs. 50.1%, P=0.040) and 5-year OS (86.5% vs. 54.7%, P=0.001). On multivariate Cox regression analysis, PORT was a significant positive prognostic factor in terms of both RFS (P=0.005) and OS (P=0.004) in patients with stage III thymomas, but not in those with stage II disease (P=0.987 and 0.968, respectively).

Conclusions

PORT improved the RFS and OS in stage III thymoma patients, but showed no survival benefit in stage II patients.

Volumetric modulated arc therapy versus intensity-modulated proton therapy in the postoperative irradiation of thymoma

BACKGROUND

To investigate the role of intensity-modulated proton therapy (IMPT) compared to volumetric modulated arc therapy (VMAT) for the radiation treatment of thymoma cancer.

METHODS

Twenty patients were retrospectively planned for IMPT [with (IMPT_R1 or IMPT_R2 according to the approach adopted) and without robust optimization] and VMAT. The results were compared according to dose-volume metrics on the clinical and planning target volumes (CTV and PTV) and the main organs at risk (heart, breasts, lungs, spinal cord and oesophagus). Estimates of the excess absolute risk (EAR) of secondary cancer induction were determined for the oesophagus, the breasts and the composite lungs. For the heart, the relative risk (RR) of chronic heart failure (CHF) was assessed.

RESULTS

IMPT and VMAT plans resulted equivalent in terms of target coverage for both the CTV and the PTV. The CTV homogeneity index resulted in 0.03 ± 0.01 and 0.04 ± 0.01 for VMAT and all IMPT plans, respectively. The conformality index resulted in 1.1 ± 0.1 and 1.2 ± 0.1 for VMAT and all IMPT plans. The mean dose to the breasts resulted in 10.5 ± 5.0, 4.5 ± 3.4, 4.7 ± 3.5 and 4.6 ± 3.4 Gy for VMAT, IMPT, IMPT_R1 and IMPT_R2. For the lungs, the mean dose was 9.6 ± 2.3, 3.5 ± 1.5, 3.6 ± 1.6 and 3.8 ± 1.4 Gy; for the heart: 8.7 ± 4.4, 4.3 ± 1.9, 4.5 ± 2.0 and 4.4 ± 2.4 Gy and for the oesophagus 8.2 ± 3.5, 2.2 ± 3.4, 2.4 ± 3.6 and 2.5 ± 3.5 Gy. The RR for CHF was 1.6 ± 0.3 for VMAT and 1.3 ± 0.2 for IMPT (R1 or R2). The EAR was 3.6 ± 0.v vs 1.0 ± 0.6 or 1.2 ± 0.6 (excess cases/10,000 patients year) for the oesophagus; 17.4 ± 6.5 vs 5.7 ± 3.2 or 6.1 ± 3.8 for the breasts and 24.8 ± 4.3 vs 8.1 ± 2.7 or 8.7 ± 2.3 for the composite lungs for VMAT and IMPT_R, respectively.

CONCLUSION

The data from this in-silico study suggest that intensity-modulated proton therapy could be significantly advantageous in the treatment of thymoma patients with particular emphasis to a substantial reduction of the risk of cardiac failure and secondary cancer induction. Robust planning is a technical pre-requisite for the safety of the delivery.

Optimal management of thymic malignancies: current perspectives

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

Type B3 thymoma with marked neuroendocrine differentiation: Report of a case

Thymomas are tumors originating from the thymus epithelial cells and are the most common tumors of the anterior mediastinum. They have been classified into types A, AB, B1, B2, and B3 by the World Health Organization. Type B3 thymoma is composed of epithelial cell sheets with mild to moderate atypia and scant lymphocytes. An association between thymic carcinoma and neuroendocrine differentiation has been observed by some authors. However, cases of type B3 thymoma with neuroendocrine differentiation are very rarely discussed in the literature. A 68-year-old woman was referred to our hospital with an abnormal shadow on a chest roentgenogram. Chest computed tomography showed that the lesion was located in the anterior mediastinum. She underwent surgery, and the tumor was diagnosed as a type B3 thymoma with neuroendocrine differentiation. An extremely rare case of a type B3 thymoma showing neuroendocrine differentiation is presented herein.

Prognostic significance of the preoperative neutrophil-to-lymphocyte ratio for complete resection of thymoma

PURPOSE

The preoperative peripheral neutrophil-to-lymphocyte ratio (NLR) is associated with a poor prognosis for various cancers. We evaluated the prognostic role of the preoperative NLR in patients with thymoma.

METHODS

We reviewed the medical records of 254 patients who underwent resection of thymic epithelial tumors at our institution. Patients were excluded if they had received steroid therapy, neoadjuvant therapy, or incomplete resection, or if they had thymic carcinoma or Good's syndrome, recurrence of thymoma, or missing data. The NLR was measured preoperatively, and outcomes of patients with a low (< 1.96) vs those with a high (≥ 1.96) NLR were compared statistically.

RESULTS

Of 159 eligible patients, 59 (37.1%) had a high NLR and 100 (62.9%) had a low NLR. Overall survival (OS), recurrence-free survival (RFS), disease-specific survival (DSS), disease-related survival (DRS), and the cumulative incidence of recurrence (CIR) differed significantly between the groups. Multivariate analyses revealed that a high NLR was independently associated with disease-related survival and a cumulative incidence of recurrence. A high NLR was also associated with a higher risk of recurrence of Masaoka stage I or II thymoma.

CONCLUSIONS

An elevated preoperative NLR was associated with poor outcomes after thymoma resection. Thus, the NLR may be a useful biomarker of the postoperative prognosis of thymoma.

Multidisciplinary Tumor Board Decision Making for Postoperative Radiotherapy in Thymic Epithelial Tumors: Insights from the RYTHMIC Prospective Cohort

INTRODUCTION

Thymic epithelial tumors (TETs) are rare intrathoracic malignancies for which surgery represents the mainstay of the treatment. Current practice for postoperative radiotherapy (PORT) is highly variable, and there is a lack of prospective, high level evidence. Réseau Tumeurs Thymiques et Cancer (RYTHMIC) is the nationwide network for TETs in France. Established in 2012, it prospectively collects data on all TET patients, for whom management is discussed at a national multidisciplinary tumor board (MTB). We assessed whether PORT decisions at the MTB were in accordance with RYTHMIC guidelines and ultimately implemented in patients.

METHODS

All consecutive patients for whom PORT was discussed at the MTB from 2012 to 2015 were identified from the RYTHMIC prospective database, and a complete review of their medical records was performed.

RESULTS

A total of 274 patients, including 243 with thymoma (89%) and 31 with thymic carcinoma (11%), were analyzed. The decision of the MTB was in accordance with guidelines in 221 patients (92%) of the 241 with stage I or III TET. An MTB decision to deliver PORT was made for 117 patients (43%). PORT was ultimately initiated in 101 patients. The most frequent reason for not delivering PORT was excessive (>3 months) delay after surgery. Dose-volume constraints defined by the International Thymic Malignancy Interest Group were followed in all but four patients.

CONCLUSION

Our data provide a unique insight into the decision-making process for PORT in TETs, highlighting the need for systematic discussion at an expert MTB, while stressing the value of current available guidelines.

Surgery for malignant lesions of the chest which extensively involved the mediastinum, lung, and heart

OBJECTIVE

Radical resection for thoracic malignancies that invade the great vessels or heart structure is an uncommon, high-risk operation. To help surgeons determine therapeutic strategy, we reviewed the patient characteristics and outcomes of combined thoracic and cardiovascular surgery for thoracic malignancies.

METHODS

Surgical resections of lung cancer, mediastinal tumor and pulmonary artery sarcoma invading great vessels or heart structures were reviewed from the literature.

RESULTS

Pneumonectomy was often performed for lung cancer invading the aorta, superior vena cava, and left atrium. Complete resection (R0), no mediastinal lymph node metastasis and without using cardiopulmonary bypass led to a good prognosis. Induction therapy was often performed for complete resection. Regarding mediastinal tumors, thymic epithelial tumors or germ cell tumors occasionally invaded the great vessels or heart structures. For these malignancies, multimodality therapy was often performed, and complete resection could be one of the prognostic factors. The resection of primary pulmonary artery sarcoma (PPAS) is also a combined thoracic and cardiovascular surgery. The primary treatment for PPAS is surgical resection; specifically, pulmonary endarterectomy and pneumonectomy, because PPAS has substantial resistance to chemotherapy or radiotherapy. The prognosis of PPAS is poor, but surgical resection has potential for long-term survival.

CONCLUSION

Although these surgeries are uncommon and invasive for the patients, selecting appropriate patients, aggressive multimodality therapy, and performing combined thoracic and cardiovascular surgery can contribute to a good outcome.

Robotic Resection of 3 cm and Larger Thymomas Is Associated With Low Perioperative Morbidity and Mortality

OBJECTIVE

The approach to thymoma resection has usually been determined by tumor size, although established guidelines do not exist. Minimally invasive approaches have been limited to tumors smaller than 5 cm, although 3 cm has been the suggested cutoff for performing an adequate oncologic procedure. No study has compared the perioperative outcomes of patients with 3 cm or larger tumors resected robotically versus sternotomy.

METHODS

We reviewed patients who underwent resection of 3 cm or larger thymomas from 2004 to 2014. Patients were divided based on approach: robotic and open thymectomy/thymomectomy.

RESULTS

Forty patients with tumors ranging from 3 to 13 cm were evaluated, 23 robotic and 17 open. Patient and tumor characteristics were similar. An R0 resection was primarily achieved: robotic, 91% (21/23); and open, 88% (15/17); P = 0.832. Adjuvant radiation rates were statistically equivalent: robotic, 17% (4/23) versus open, 41% (7/17); P = 0.191. Major postoperative complications were comparable: robotic, 4% (1/23) versus open, 29% (4/17); P = 0.184. Median chest tube duration was shorter for robotic (1 day) versus open (3 days); P = 0.001. The robotic approach had a shorter median intensive care unit stay compared to open (0 days vs 1 day); P = 0.024. The median hospital stay was shorter for robotic (2 days) versus open (5 days); P < 0.001.

CONCLUSIONS

In 3 cm or larger thymomas, robotic thymectomy is feasible based on the ability to achieve a complete resection with similar adjuvant radiation therapy rates. Perioperatively, robotic thymectomy is associated with lower morbidity; and shorter chest tube duration, intensive care unit stay, and hospital stay compared to open. However, oncologic outcomes are immature and require prolonged surveillance.

[Role of Postoperative Radiotherapy for Stage I/II/III Thymic Tumor - Results of the ChART Retrospective Database]

背景与目的

胸腺肿瘤术后放疗尚存在争议，此研究目的为评价术后放疗在Ⅰ期-Ⅲ期胸腺肿瘤中的作用。

方法

搜索中国胸腺瘤研究协作组（Chinese Alliance of Research for Thymomas, ChART）数据库中1994年至2012年接受手术切除未行新辅助治疗的Ⅰ期-Ⅲ期胸腺肿瘤患者的资料。对临床病理资料进行单因素、多因素分析，Cox比例风险模型用于决定死亡风险比。

结果

ChART数据库中Ⅰ期-Ⅲ期胸腺肿瘤共1, 546例。其中649例（41.98%）接受术后放疗。术后放疗与性别、组织学类型（World Health Organization, WHO）、胸腺切除程度、是否完全切除、Masaoka-Koga分期及辅助化疗相关。手术后辅助放疗患者5年、10年总生存和无瘤生存分别为90%和80%、81%和63%，而单纯手术者5年、10年总生存和无瘤生存分别为96%和95%、92%和90%，两组生存有统计学差异（P=0.001, P＜0.001）。单因素表明年龄、组织学分类（WHO）、Masaoka-Koga分期、是否完全切除和术后放疗与总生存相关。多因素分析提示组织学分类（WHO）（P=0.001）、Masaoka-Koga分期（P=0.029）和是否完全切除（P=0.003）是总生存的独立预后因素。单因素分析表明性别、重症肌无力、组织学分类、Masaoka-Koga分期、手术方式、术后放疗和是否完全切除与无瘤生存相关。多因素分析表明组织学类型（P＜0.001）、Masaoka-Koga分期（P=0.005）和是否完全切除（P=0.006）是无瘤生存的独立预后因素。亚组分析表明不完全切除患者接受术后放疗可以提高总生存和无瘤生存（P=0.010, P=0.017）。然而，完全切除者接受术后放疗则会降低总生存和无瘤生存（P＜0.001, P＜0.001）。

结论

此回顾性研究表明不完全切除Ⅰ期-Ⅲ期胸腺肿瘤患者术后放疗可以提高总生存和无瘤生存。但是，对于完全切除患者，术后放疗总体上并未显示出生存获益。

The Impact of Postoperative Radiotherapy for Thymoma and Thymic Carcinoma

INTRODUCTION

The optimal role for postoperative radiotherapy (PORT) for thymoma and thymic carcinoma remains controversial. We used the National Cancer Data Base to investigate the impact of PORT on overall survival (OS).

METHODS

Patients who underwent an operation for thymoma or thymic carcinoma were categorized into Masaoka-Koga stage groups I to IIA, IIB, III, and IV. Patients who did not undergo an operation or those who received preoperative radiation were excluded. Kaplan-Meier estimates of OS and univariate and multivariate Cox proportional hazards regression analyses were performed. Propensity score-matched analyses were performed to further control for baseline confounders.

RESULTS

From 2004 to 2012, 4056 patients were eligible for inclusion, 2001 of whom (49%) received PORT. On multivariate analysis of OS in the thymoma cohort adjusted for age, WHO histologic subtype, Masaoka-Koga stage group, surgical margins, and chemotherapy administration, PORT was associated with superior OS (hazard ratio [HR] = 0.72, p = 0.001). Propensity score-matched analyses confirmed the survival advantage associated with PORT. Subset analysis indicated longer OS in association with PORT for patients with stage IIB thymoma (HR = 0.61, p = 0.035), stage III (HR = 0.69, p = 0.020), and positive margins (HR = 0.53, p < 0.001). The impact of PORT for stage I to IIA disease did not reach significance (HR = 0.76, p = 0.156).

CONCLUSIONS

In this large database analysis of PORT for thymic tumors, PORT was associated with longer OS, with the greatest relative benefits observed for stage IIB to III disease and positive margins. In the absence of randomized studies assessing the value of PORT, these data may inform clinical practice.

Mutation analysis of the EGFR gene and its downstream signaling pathway in thymic carcinoma patients from a Chinese Han population

INTRODUCTION

For thymic carcinoma (TC), which is a rare epithelial neoplasm of the thymus gland, median survival with current treatments is only 2 years.

OBJECTIVES

Mutations in the epidermal growth factor receptor (EGFR) gene or its downstream effectors may cause constitutive activation that leads to cell proliferation and metastases. Thus, molecular profiling is essential for selecting TC patients who may respond to anti-EGFR therapies.

METHODS

Genomic DNA was extracted from 61 histological samples of TCs. Real-time polymerase chain reaction (PCR) and direct sequencing were used to assess the mutations in the EGFR downstream pathway.

RESULTS

Gene mutations were identified in seven patients (11.5%). In particular, the identified mutations included four mutations in the KRAS gene, one mutation in the BRAF gene, one mutation in the PIK3CA gene, and only one mutation in the EGFR gene itself. Gene mutations in the EGFR downstream pathway were associated with shorter survival time and were observed to be an independent prognostic factor for TC patients.

CONCLUSION

Mutations in the EGFR downstream pathway are not rare in TCs. These data offer interesting possibilities for the future management of TCs, particularly in the era of new targeted therapies.

Postoperative radiotherapy and tumor recurrence after complete resection of stage II/III thymic tumor: a meta-analysis of cohort studies

BACKGROUND

Whether postoperative radiotherapy (PORT) is effective for reducing the recurrence risk in patients who received complete resection of the stage II or III thymic tumors has not been determined. A meta-analysis was performed by combining the results of all available controlled trials.

METHODS

PubMed, Cochrane's Library, and the Embase databases were searched for studies which compared the recurrence data for patients with complete resection of the stage II or III thymic tumors assigned to an observing group, or a PORT group. A random effect model was applied to combine the results.

RESULTS

Nineteen studies, all designed as retrospective cohort studies were included. These studies included 663 patients of PORT group and 617 patients of observing group. The recurrence rate for the patients in PORT group and observing group were 12.4% and 11.5%, respectively. Results of our study indicated that PORT has no significant influence on recurrent risk in patients with stage II or III thymic tumor after complete resection (odds ratio 1.02, 95% confidence interval 0.55-1.90, P=0.96). When stratified by stages, our meta-analyses did not indicate any significant effects of PORT on recurrent outcomes in either the stage II or the stage III patients. Moreover, subsequent analysis limited to studies only including patients with thymoma or thymic carcinoma also did not support the benefits of PORT on recurrent outcomes.

CONCLUSION

Although derived from retrospective cohort studies, current evidence did not support any benefit of PORT on recurrent risk in patients with complete resection of the stage II or III thymic tumors.

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

背景与目的

探讨术前病理学诊断在胸腺肿瘤诊断和治疗中的价值及其对胸腺肿瘤治疗的影响。

方法

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

结果

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

结论

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

Postoperative Radiation Therapy Is Associated with Longer Overall Survival in Completely Resected Stage II and III Thymoma-An Analysis of the International Thymic Malignancies Interest Group Retrospective Database

OBJECTIVES

The aim of this study was to determine whether postoperative radiation therapy (PORT) is associated with an overall survival (OS) benefit in patients with completely resected Masaoka or Masaoka-Koga stage II and III thymoma.

METHODS

All patients with completely resected (R0) stage II or III thymoma were identified in a large database of the International Thymic Malignancy Interest Group. Clinical, pathologic, treatment, and follow-up information were extracted. OS was the primary end point. A univariate analysis using the log-rank test was performed, and a multivariate Cox model was created to identify factors associated with OS.

RESULTS

Of 1263 patients meeting the selection criteria, 870 (69%) had stage II thymoma. The WHO histologic subtype was A/AB in 360 patients (30%) and B1/B2/B3 in 827 (70%). PORT was given to 55% of patients (n = 689), 15% (n = 180) received chemotherapy, and 10% (n = 122) received both. The 5- and 10-year OS rates for patients having undergone an operation plus PORT were 95% and 86%, respectively, compared with 90% and 79% for patients receiving an operation alone (p = 0.002). This OS benefit remained significant when patients with stage II (p = 0.02) and stage III thymoma (p = 0.0005) were analyzed separately. On multivariate analysis, earlier stage, younger age, absence of paraneoplastic syndrome, and PORT were significantly associated with improved OS.

CONCLUSIONS

We observed an OS benefit with the use of PORT in completely resected stage II and III thymoma. In the absence of a randomized trial, this represents the most comprehensive analysis of individual patient data and strong evidence in favor of PORT in this patient population.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

The role of postoperative radiotherapy for stage I/II/III thymic tumor-results of the ChART retrospective database

BACKGROUND

Postoperative radiotherapy (PORT) for thymic tumor is still controversial. The object of the study is to evaluate the role of PORT for stage I to III thymic tumors.

METHODS

The Chinese Alliance for Research in Thymomas (ChART) was searched for patients with stage I to III thymic tumors who underwent surgical resection without neoajuvant therapy between 1994 and 2012. Univariate and multivariate survival analyses were performed. Cox proportional hazard model was used to determine the hazard ratio for death.

RESULT

From the ChART database, 1,546 stage I to III patients were identified. Among these patients, 649 (41.98%) received PORT. PORT was associated with gender, histological type (World Health Organization, WHO), thymectomy extent, resection status, Masaoka-Koga stage and adjuvant chemotherapy. The 5-year and 10-year overall survival (OS) rates and disease-free survival (DFS) rates for patients underwent surgery followed by PORT were 90% and 80%, 81% and 63%, comparing with 96% and 95%, 92% and 90% for patients underwent surgery alone (P=0.001, P<0.001) respectively. In univariate analysis, age, histological type (WHO), Masaoka-Koga stage, completeness of resection, and PORT were associated with OS. Multivariable analysis showed that histological type (WHO) (P=0.001), Masaoka-Koga stage (P=0.029) and completeness of resection (P=0.003) were independently prognostic factors of OS. In univariate analysis, gender, myasthenia gravis, histological subtype, Masaoka-Koga stage, surgical approach, PORT and completeness of resection were associated with DFS. Multivariate analysis showed that histological subtype (P<0.001), Masaoka-Koga stage (P=0.005) and completeness of resection (P=0.006) were independent prognostic factors for DFS. Subgroup analysis showed that patients with incomplete resection underwent PORT achieved better OS and DFS (P=0.010, 0.017, respectively). However, patients with complete resection underwent PORT had the worse OS and DFS (P<0.001, P<0.001, respectively).

CONCLUSIONS

The current retrospective study indicates that PORT after incomplete resection could improve OS and DFS for patients with stage I to III thymic tumors. However for those after complete resection, PORT does not seem to have any survival benefit on the whole.

Thymoma and thymic carcinomas

Thymomas (Ts) and thymic carcinomas (TCs) are rare tumours of the mediastinum with an incidence rate of 1.7/million per year in Europe. Histological classification is based on rate of non-malignant-appearing thymic epithelial cells and proportions of lymphocytes (A, AB, B1, B2, B3, and C), while staging system concerns localisation of the involved areas. Surgery is the mainstay of treatment with a 10-year survival of 80%, 78%, 75%, and 42% for stages I, II, III and IV, respectively, with an R0 resection. Radiotherapy has a role in selected cases (stage III patients or R1-2 residual) and platinum-based chemotherapy remains the standard of care for patients with advanced disease. A multimodality approach would be advisable when surgery is not recommended. Since molecular aberrations are poorly understood and few responses are reported, targeted therapies are yet being studied. In this review, we describe key aspects of clinical management for Ts and TCs.

Survival Impact of Adjuvant Radiation Therapy in Masaoka Stage II to IV Thymomas: A Systematic Review and Meta-analysis

PURPOSE

To evaluate the survival impact of postoperative radiation therapy (PORT) in stage II to IV thymomas, using systematic review and meta-analysis.

METHODS AND MATERIALS

A database search was conducted with EMBASE, PubMed, Web of Science, Cochrane Library, and Ovid from inception to August 2015. Thymic carcinomas were excluded, and studies comparing overall survival (OS) with and without PORT in thymomas were included. The hazard ratios (HRs) of OS were extracted, and a random-effects model was used in the pooled analysis.

RESULTS

Seven retrospective series with a total of 1724 patients were included and analyzed. Almost all of the patients underwent macroscopically complete resection, and thymoma histology was confirmed by the World Health Organization criteria. In the overall analysis of stage II to IV thymomas, OS was not altered with the receipt of PORT (HR 0.79, 95% confidence interval [CI] 0.58-1.08). Although PORT was not associated with survival difference in Masaoka stage II disease (HR 1.45, 95% CI 0.83-2.55), improved OS was observed with the addition of PORT in the discrete pooled analysis of stage III to IV (HR 0.63, 95% CI 0.40-0.99). Significant heterogeneity and publication bias were not found in the analyses.

CONCLUSIONS

From the present meta-analysis of sole primary thymomas, we suggest the potential OS benefit of PORT in locally advanced tumors with macroscopically complete resection, but not in stage II disease. Further investigations with sufficient survival data are needed to establish detailed treatment indications.

Development of the international thymic malignancy interest group international database: an unprecedented resource for the study of a rare group of tumors

BACKGROUND

Our knowledge of thymic malignancies has largely been derived from small, single-institution series. Recognition of the need for broad collaboration led to the creation of the International Thymic Malignancy Interest Group (ITMIG) and the development of a large, centralized database to advance knowledge of these rare tumors.

METHODS

A multidisciplinary Database Committee was convened to define a common set of data elements a priori. Retrospective data were solicited from ITMIG members and collated using standardized fields. Patients with thymoma, thymic carcinoma, or thymic carcinoid were included.

RESULTS

Over a 6-month period, 47 institutions spanning 15 countries contributed a total of 6097 cases (mean, 129 [range, 10-1209]). The sex distribution was equal for thymomas, but there was a greater proportion of men with thymic carcinoma and thymic carcinoid (p < 0.0001). Nearly all cases (99%) were treated surgically. WHO type B2 was the most frequent histologic classification among thymomas, whereas squamous was the most common among thymic carcinomas. In total, 38% of patients with thymoma had myasthenia gravis compared with less than or equal to 5% for thymic carcinoma and thymic carcinoid. Median overall survival was 18.9 years (95% confidence interval [CI], 17.4-20.3) for thymoma, 6.8 years (95% CI, 5.5-7.9) for thymic carcinoma, and 7.5 years (95% CI, 6.5-8.5) for thymic carcinoid.

CONCLUSIONS

The rapid creation of the ITMIG database demonstrates the feasibility of international collaboration for this rare set of malignancies and attests to the engagement of its membership. This database represents the largest collective data set ever assembled and provides an unprecedented resource for research of these tumors.

The IASLC/ITMIG Thymic Epithelial Tumors Staging Project: proposals for the T Component for the forthcoming (8th) edition of the TNM classification of malignant tumors

Despite longstanding recognition of thymic epithelial neoplasms, there is no official American Joint Committee on Cancer/Union for International Cancer Control stage classification. This article summarizes proposals for classification of the T component of stage classification for use in the 8th edition of the tumor, node, metastasis classification for malignant tumors. This represents the output of the International Association for the Study of Lung Cancer and the International Thymic Malignancies Interest Group Staging and Prognostics Factor Committee, which assembled and analyzed a worldwide database of 10,808 patients with thymic malignancies from 105 sites. The committee proposes division of the T component into four categories, representing levels of invasion. T1 includes tumors localized to the thymus and anterior mediastinal fat, regardless of capsular invasion, up to and including infiltration through the mediastinal pleura. Invasion of the pericardium is designated as T2. T3 includes tumors with direct involvement of a group of mediastinal structures either singly or in combination: lung, brachiocephalic vein, superior vena cava, chest wall, and phrenic nerve. Invasion of more central structures constitutes T4: aorta and arch vessels, intrapericardial pulmonary artery, myocardium, trachea, and esophagus. Size did not emerge as a useful descriptor for stage classification. This classification of T categories, combined with a classification of N and M categories, provides a basis for a robust tumor, node, metastasis classification system for the 8th edition of American Joint Committee on Cancer/Union for International Cancer Control stage classification.

Adjuvant treatment in patients at high risk of recurrence of thymoma: efficacy and safety of a three-dimensional conformal radiation therapy regimen

Background

The clinical benefits of postoperative radiation therapy (PORT) for patients with thymoma are still controversial. In the absence of defined guidelines, prognostic factors such as stage, status of surgical margins, and histology are often considered to guide the choice of adjuvant treatment (radiotherapy and/or chemotherapy). In this study, we describe our single-institution experience of three-dimensional conformal PORT administered as adjuvant treatment to patients with thymoma.

Methods

Twenty-two consecutive thymoma patients (eleven male and eleven female) with a median age of 52 years and treated at our institution by PORT were analyzed. The patients were considered at high risk of recurrence, having at least one of the following features: stage IIB or III, involved resection margins, or thymic carcinoma histology. Three-dimensional conformal PORT with a median total dose on clinical target volume of 50 (range 44–60) Gy was delivered to the tumor bed by 6–20 MV X-ray of the linear accelerator. Follow-up after radiotherapy was done by computed tomography scan every 6 months for 2 years and yearly thereafter.

Results

Two of the 22 patients developed local recurrence and four developed distant metastases. Median overall survival was 100 months, and the 3-year and 5-year survival rates were 83% and 74%, respectively. Median disease-free survival was 90 months, and the 5-year recurrence rate was 32%. On univariate analysis, pathologic stage III and presence of positive surgical margins had a significant impact on patient prognosis. Radiation toxicity was mild in most patients and no severe toxicity was registered.

Conclusion

Adjuvant radiotherapy achieved good local control and showed an acceptable toxicity profile in patients with high-risk thymoma.

Patterns and predictors of recurrence after radical resection of thymoma

BACKGROUND

Recurrence of thymomas even after complete resection is common, but the relapse patterns remain controversial. This study aimed to define the patterns and predictors of relapse after complete resection of thymoma.

METHODS

A single-institution retrospective study was performed with 331 patients who underwent radical resection of thymoma between 1991 and 2012.

RESULTS

After a median follow-up of 59 months, the recurrence rate was 6.9% (23/331). Relapse occurred in 23 patients with the pleura (14) and tumor bed (6) as the most common sites of recurrence. According to the definitions of the International Thymic Malignancy Interest Group, 10 (43.5%) patients had local relapse, 15 (65.2%) had regional relapse, 10 (43.5%) had distant relapse. The difference in survival following relapse between lung and regional relapse was statistically significant (P=0.027) but that between lung and distant relapse was not (P=0.808). The recurrence rates correlated with the initial Masaoka stage. Further, recurrence also correlated with World Health Organization (WHO) tumor type. The recurrence-free survival rates in patients with tumor size ⩾8 cm were worse than those of patients with tumor size <8 cm (P=0.007). Tumor size was also correlated with stage (r=0.110). As tumor becomes larger, the stage is more advanced (P=0.023). Multivariate analysis showed that Masaoka stage (P=0.005), tumor size (P=0.033), and WHO histological type (P=0.046) were predictive factors of relapse.

CONCLUSION

Regional recurrence is the most common relapse pattern but local and distant relapse are also common. Advanced Masaoka stage, larger tumor size, and type B3 are risk factors of recurrence. Lung relapse should be considered distant relapse. Further, tumor size was correlated with Masaoka stage and therefore should be considered in the staging system.

Postoperative radiotherapy is effective for thymic carcinoma but not for thymoma in stage II and III thymic epithelial tumors: the Japanese Association for Research on the Thymus Database Study

BACKGROUND

The efficacy of postoperative radiotherapy (PORT) for thymic epithelial tumors is still controversial. Using the Japanese Association for Research on the Thymus (JART) database, this study was aimed at clarifying the efficacy of PORT for Masaoka stage II and III thymic carcinoma and thymoma.

METHODS

The JART database registered the records of 2835 patients collected from 32 Japanese institutions from 1991 to 2010. Thymic carcinoma and thymoma at stage II or III were extracted. The efficacy of PORT with respect to relapse-free survival (RFS) and overall survival (OS) was evaluated with the Kaplan-Meier method and Cox regression analysis.

RESULTS

There were 1265 patients in all: 155 thymic carcinoma cases (12.3%) and 1110 thymoma cases (87.7%). Eight hundred ninety-five (70.8%) were at stage II, and 370 (29.2%) were at stage III. Four hundred three cases (31.9%) underwent PORT. PORT for stage II and III thymic carcinoma was associated with increasing RFS (hazard ratio, 0.48; 95% confidence interval, 0.30-0.78; P = .003) but was not associated with OS (hazard ratio, 0.94; 95% confidence interval, 0.51-1.75; P = .536). PORT for stage II and III thymoma was not associated with RFS or OS (P = .350). A subgroup analysis of stage III thymoma showed no factor associated with the efficacy of PORT.

CONCLUSIONS

In this study, PORT did not increase RFS or OS for stage II or III thymoma but increased RFS for stage II and III thymic carcinoma.

Management of thymic tumors: a European perspective

Thymic tumors are rare mediastinal tumors, which are considered as orphan diseases due to their low prevalence. The most recent histologic classification divides thymic tumors into thymomas, thymic carcinomas (TC) and neuroendocrine thymic tumors (NETT). Until recently, clinical research on thymic tumors has been primarily represented by single-institution experiences usually scattered over a long time period in order to accumulate a sufficient number of patients for clinical analysis. Europe has played a pivotal role in the advancement of the clinical research on thymus in the past years. In the last decade, there has been an increased interest in thymic malignancies in the scientific community. The European Society of Thoracic Surgeons (ESTS), the most representative society of general thoracic surgeons in the world, established a dedicated thymic working group in 2010 with the intent to provide a platform among ESTS members with a specific interest in thymic malignancies. The present review is intended to provide, through the description of the activity of the ESTS thymic working group and its published results, an overview of the European contribution to the thymic research. A brief overview of the state-of-the-art of clinical presentation, diagnosis, staging and histologic classification of thymic tumors is also provided, along with the most recent therapeutic advancements.

Therapy for thymic epithelial tumors

Thymoma is the most common tumor of the anterior mediastinum. This tumor is associated with unique paraneoplastic syndromes. The rarity of this tumor has somewhat obscured the optimal treatment for this disease. The World Health Organization classification system, which published in 1999, appears to be an advance in our understanding of thymoma. The Masaoka classification is now the most widely accepted and is an excellent predictor of the prognosis of thymoma. Now the International Thymic Malignancy Interest Group is currently engaged in the development of a validated formal TNM classification system for thymic malignancies. The optimal treatment of thymoma is performed according to its clinical stage. Surgery remains the mainstay of treatment for thymic epithelial tumors. Minimally invasive surgery including thoracoscopic surgery and robotic surgery for stage I and II thymomas is increasing now. The value of postoperative radiotherapy in completely resected stage II or III tumors is questionable. As thymomas have a moderate response rate to chemotherapy or radiotherapy, multimodality therapy involving surgery, chemotherapy and radiotherapy appears to increase the rate of complete resection and survival in the advanced (stage III and IV) thymomas.

Tumours of the thymus: a cohort study of prognostic factors from the European Society of Thoracic Surgeons database

OBJECTIVES

A retrospective database was developed by the European Society of Thoracic Surgeons, collecting patients submitted to surgery for thymic tumours to analyse clinico-pathological prognostic predictors.

METHODS

A total of 2151 incident cases from 35 institutions were collected from 1990 to 2010. Clinical-pathological characteristics were analysed, including age, gender, associated myasthenia gravis stage (Masaoka), World Health Organization histology, type of thymic tumour [thymoma, thymic carcinoma (TC), neuroendocrine thymic tumour (NETT)], type of resection (complete/incomplete), tumour size, adjuvant therapy and recurrence. Primary outcome was overall survival (OS); secondary outcomes were the proportion of incomplete resections, disease-free survival and the cumulative incidence of recurrence (CIR).

RESULTS

A total of 2030 patients were analysed for OS (1798 thymomas, 191 TCs and 41 NETTs). Ten-year OS was 0.73 (95% confidence interval 0.69-0.75). Complete resection (R0) was achieved in 88% of the patients. Ten-year CIR was 0.12 (0.10-0.15). Predictors of shorter OS were increased age (P < 0-001), stage [III vs I HR 2.66, 1.80-3.92; IV vs I hazard ratio (HR) 4.41, 2.67-7.26], TC (HR 2.39, 1.68-3.40) and NETT (HR 2.59, 1.35-4.99) vs thymomas and incomplete resection (HR 1.74, 1.18-2.57). Risk of recurrence increased with tumour size (P = 0.003), stage (III vs I HR 5.67, 2.80-11.45; IV vs I HR 13.08, 5.70-30.03) and NETT (HR 7.18, 3.48-14.82). Analysis using a propensity score indicates that the administration of adjuvant therapy was beneficial in increasing OS (HR 0.69, 0.49-0.97) in R0 resections.

CONCLUSIONS

Masaoka stages III-IV, incomplete resection and non-thymoma histology showed a significant impact in increasing recurrence and in worsening survival. The administration of adjuvant therapy after complete resection is associated with improved survival.