Comparison of stages I-II thymoma treated by complete resection with or without adjuvant radiation

Case Reports: A role of postoperative radiation therapy in completely resected early stage intrathyroid thymic carcinoma: a case report and literature review of the diagnosis and treatment

Background

Intrathyroid thymic carcinoma (ITTC) is a rare malignant tumor of the thyroid, probably arising from ectopic thymus or branchial pouch remnants. Most of the literature recommended radical resection as the fundamental treatment for ITTC, and postoperative radiation appears to be able to reduce the recurrence rate in patients with advanced ITTC. However, the issue of adjuvant radiotherapy in completely resected early-stage ITTC has been controversial.

Case presentation

Here, we reported a new case of early-stage ITTC that treated with total thyroidectomy and the right central neck dissection. Postoperative external beam radiation therapy (50.0 Gy/25 fractions) was given to the thyroid bed and bilateral cervical lymph node area since the tumor involved part of the sternal thyroid muscle. At 4-year follow-up after completion of radiotherapy, she is without evidence of locally recurrent or distant disease.

Conclusion

Since there are no current guidelines for early-stage ITTC, in combination with this case and previous literature, we may suggest routine adjuvant radiotherapy should be considered in patients with incompletely resected tumors and extraparenchymal extension of ITTC. Moreover, we summarized comprehensive and advanced diagnosis, treatment, prognosis of ITTC and comparison between ITTC, primary squamous cell carcinoma of thyroid gland, differentiated thyroid cancer, and anaplastic thyroid cancer.

Prognostic factors and role of postoperative radiotherapy in surgically resected thymomas

Objective

To investigate the prognostic factors in and role of postoperative radiotherapy (PORT) for surgically resected thymomas.

Methods

A total of 1540 patients with pathologically confirmed thymomas undergoing resection between 2000 and 2018 were identified retrospectively from the SEER (Surveillance, Epidemiology, and End Results) database. Tumors were restaged as local (limited to thymus), regional (invasion to mediastinal fat and other neighboring structures), or distant stage. Disease-specific survival (DSS) and overall survival (OS) were estimated by the Kaplan-Meier method and the log-rank test. Adjusted hazard ratios (HRs) with 95% CIs were calculated by Cox proportional hazards modeling.

Results

Tumor stage and histology were independent predictors of both DSS (regional: HR, 3.711; 95% CI, 2.006-6.864; distant: HR, 7.920; 95% CI, 4.061-15.446; type B2/B3: HR, 1.435; 95% CI, 1.008-2.044) and OS (regional: HR, 1.461; 95% CI, 1.139-1.875; distant: HR, 2.551; 95% CI, 1.855-3.509; type B2/B3: HR, 1.409; 95% CI, 1.153-1.723). For patients with regional stage and type B2/B3 thymomas, PORT was associated with better DSS after thymectomy/thymomectomy (HR, 0.268; 95% CI, 0.099-0.727), but the association was not significant after extended thymectomy (HR, 1.514; 95% CI, 0.516-4.44). Among patients with lymph node metastases, those who received PORT (HR, 0.372; 95% CI, 0.146-0.949), chemotherapy (HR, 0.843; 95% CI, 0.303-2.346), or both (HR, 0.296, 95% CI, 0.071-1.236) had a better OS.

Conclusions

The extent of invasion and tumor histology were independent predictors of worse survival following surgical resection of thymoma. Patients with regional invasion and type B2/B3 thymoma who undergo thymectomy/thymomectomy may benefit from PORT, while patients with nodal metastases may benefit from multimodal therapy, including PORT and chemotherapy.

Surgical, Radiation, and Systemic Treatments of Patients With Thymic Epithelial Tumors: A Systematic Review

INTRODUCTION

Thymic epithelial tumors are rare and are classified as thymoma, thymic carcinoma, and thymic neuroendocrine tumors. The objective of this systematic review was to evaluate the treatment options for patients with thymic epithelial tumors.

METHODS

This systematic review was developed by Ontario Health (Cancer Care Ontario)'s Program in Evidence-Based Care and by the Lung Cancer Disease Site Group. MEDLINE, EMBASE, and the Cochrane Library were searched for studies comparing surgical, radiotherapy, or systemic treatments against any combination of these treatments in patients with thymic epithelial tumors. Meta-analyses were conducted with clinically homogenous studies.

RESULTS

A total of 106 studies were included, mainly from observational studies. There was an overall survival benefit with postoperative radiotherapy for patients with thymic carcinoma (hazard ratio = 0.65, 95% confidence interval: 0.47-0.89) and for patients with thymoma (hazard ratio = 0.70, 95% confidence interval: 0.59-0.82), especially for those with a high risk for mortality. Patients with thymic carcinoma or thymoma had a response to chemotherapy. Selection bias affected the results for studies that evaluated neoadjuvant chemotherapy or minimally invasive surgical techniques. Furthermore, the overall survival benefit found for adjuvant chemotherapy may have been confounded by the administration of postoperative radiotherapy.

CONCLUSIONS

For patients with thymoma or thymic carcinoma, the literature is of low quality and subject to bias. There were overall survival benefits with postoperative radiotherapy. The results of this systematic review were used to inform treatment recommendations in a clinical practice guideline. Future large-scale prospective studies that control for confounders are needed.

Clinical outcomes for patients with thymoma and thymic carcinoma after undergoing different front-line chemotherapy regimens

Background

Front‐line platinum‐base chemotherapy for advanced thymoma and thymic carcinoma (TC) improves resectability and prolongs patients' overall survival (OS). In this study, we evaluated patients' outcomes given different front‐line regimens: cisplatin, doxorubicin, and cyclophosphamide (CAP); cisplatin and etoposide (EP); or cisplatin and paclitaxel (TP).

Materials and Methods

We retrospectively evaluated the medical records of patients with advanced thymoma and TC who were treated at our medical center between 2005 and 2015. We investigated objective response rates (ORRs), progression‐free survival (PFS), and OS after undergoing different front‐line regimens.

Results

Among the 108 enrolled patients, 37 (34%) had thymoma and 71 (66%) had TC; 45 received CAP, 36 received EP, and 27 received TP regimens. The ORRs of patients receiving CAP, EP, and TP were 51%, 50%, and 41%, respectively. For patients with stage III and IVA disease, the median PFS after CAP, EP, and TP were 34.5, 26.4, and 18.0 months (p = 0.424), respectively, and the 5‐year OS rates were 84.9%, 70.6%, and 60.0% (p = 0.509). In patients with stage IVB disease, the median PFS were 9.4, 8.2, and 11.6 months after undergoing CAP, EP, and TP (p = 0.173), respectively, and the 5‐year OS rates were 41.1%, 39.1%, and 14.3% (p = 0.788). TC pathology subtype and liver metastasis were associated with poor OS. Three patients with stage IVB TC had an OS of more than 5 years.

Conclusion

Different front‐line chemotherapy regimens may provide similar long‐term PFS and OS in patients with advanced thymoma and TC. In addition to TC and liver metastasis were associated with poor OS, other potential prognostic factors are warranted for studying.

Postoperative radiotherapy for completely resected thymoma: Differing roles in masaoka stage II and stage III disease

PURPOSE

The efficacy of radiotherapy for treating thymomas is unclear. The goal of this study was to analyze overall survival (OS) and disease-free survival (DFS) among thymoma patients to determine the impact of postoperative radiotherapy (PORT) on thymoma outcomes.

METHODS

Recorded cases of thymoma at Xinqiao Hospital were retrospectively analyzed from 1991 to 2019. Data on stage II and III thymomas were extracted from medical records. This study evaluated OS and DFS and compared outcomes between surgery and surgery-plus-radiation groups. The Kaplan-Meier method and Cox regression analysis were used to compare DFS and OS for these groups.

RESULTS

Of the 205 patients included in the current study, 142 (69.3%) presented with stage II disease and 63 (30.7%) presented with stage III disease. The median follow-up was 84.3 months. PORT did not statistically significantly improve OS (P = 0.613) and DFS (P = 0.445) in stage II thymoma patients (compared with surgery alone). However, our subgroup analysis showed a statistically significant difference in DFS in patients with stage III thymoma (P = 0.044).

CONCLUSION

Although the routine use of postoperative radiotherapy in patients with thymoma does not appear warranted, patients with stage III thymoma may benefit from adjuvant radiation. These findings, if confirmed, will provide valuable information to guide medical decision-making for thymoma treatment.

Difficult Decisions in Minimally Invasive Surgery of the Thymus

A minimally invasive resection of thymomas has been accepted as standard of care in the last decade for early stage thymomas. This is somewhat controversial in terms of higher-staged thymomas and myasthenia gravis patients due to the prognostic importance of complete resections and the indolent characteristics of the disease process. Despite concerted efforts to standardize minimally invasive approaches, there is still controversy as to the extent of excision, approach of surgery, and the platform utilized. In this article, we aim to provide our surgical perspective of thymic resection and a review of the existing literature.

Robotic vs. Transsternal Thymectomy: A Single Center Experience over 10 Years

Introduction: Thymomas are the most common tumors of the mediastinum. Traditionally, thymectomies have been performed through a transsternal (TS) approach. With the development of robot-assisted thoracic surgery (RATS), a promising, minimally invasive, alternative surgical technique for performing a thymectomy has been developed. In the current paper, the oncological and surgical outcomes of the TS vs. RATS thymectomies are discussed. Methods: For the RATS thymectomy, two 8 mm working ports and one 12 mm camera port were used. In the transsternal approach, we performed a median sternotomy and resected the thymic tissue completely, in some cases en bloc with part of the lung and/or, more frequently, a partial pericardiectomy with consequent reconstruction using a bovine pericardial patch. The decisions for using the TS vs. RATS methods were mainly based on the suspected tumor invasion of the surrounding structures on the preoperative CT scan and tumor size. Results: Between January 2010 and November 2020, 149 patients were submitted for an anterior mediastinal tumor resection at our institution. A total of 104 patients met the inclusion criteria. One procedure was performed through a hemi-clamshell incision. A total of 81 (78%) patients underwent RATS procedures, and 22 (21.1%) patients were treated using a transsternal (TS) tumor resection. Thymoma was diagnosed in 53 (51%) cases. In the RATS group, the median LOS was 3.2 ± 2.8 days and the median tumor size was 4.4 ± 2.37 cm compared to the TS group, which had a median LOS of 9 ± 7.3 days and a median tumor size of 10.4 ± 5.3 cm. Both differences were statistically significant (p < 0.001). Complete resection was achieved in all patients. Conclusion: While larger and infiltrating tumors (i.e., thymic carcinomas) were usually resected via a sternotomy, the RATS procedure is a good alternative for the resection of thymomas of up to 9.5 cm, and the thymectomy is a strong approach for myasthenia gravis. The oncological outcomes and survival rates were not influenced by the chosen approach.

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.

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 for thymomas: a multicentric retrospective evaluation from three Italian centers and review of the literature

Background

Thymoma is a rare mediastinal neoplasia. Surgery is the backbone of the treatment, but the role of postoperative radiotherapy (PORT) remains controversial. We aimed to obtain data on survival and safety in patients treated with PORT in three different Italian institutions.

Methods

We retrospectively analyzed 183 consecutive patients who underwent surgery from 1981 to 2015. According to the Masaoka-Koga staging system, 39.3%, 32.7%, 18.6% and 9.8% patients were in stage I, II, III and IV of disease, respectively. PORT was indicated in 114 patients (62.3%), while 69 subjects underwent surgery alone. Complete resection was obtained in 68 patients who underwent PORT. Adverse events (AEs) were graded according to CTCAE v4.0. We analyzed the recent literature to describe the current reports on PORT for resected thymoma.

Results

Mean follow-up was 130 months (range, 3–417 months). Overall survival (OS) at 1-, 5- and 10-year from surgery was 98.3%, 90.2% and 69.7% respectively. One-, 5- and 10-year disease specific survival (DSS) was 98.9%, 92.3% and 89.8% respectively. Disease free survival (DFS) at 1, 5 and 10 years from surgery was 96.7%, 88.3% and 82.8% respectively. Univariate analysis showed that complete resection, cell histology A-AB-B1 and stages I–II were significant predictors of better DSS and DFS. Multivariate analysis showed that sex, R0 margins and WHO histology was independent prognostic factors. Among patients treated with PORT, a trend towards better OS was evident with Masaoka stage I–II (P=0.09). Patients with R0 margins treated with PORT showed better OS and DSS (P=0.05). No differences in DSS for performance status (P=0.70), WHO histology (P=0.19), paraneoplastic syndrome (P=0.23) and surgical procedure (P=0.53) were evident. Patients treated with PORT had a higher level of acute AEs compared to surgery alone, but none of these was graded ≥3.

Conclusions

Our results confirmed that patients with incompletely resected thymoma had the worst OS and DSS. High grade acute toxicity was not different between PORT and surgery alone. Other trials reported a significant benefit in OS, DSS and DFS in stage IIb–IV thymoma treated with PORT.

Ectopic cervical thymoma with myasthenia gravis: a rare association

Thymic masses are one of the most common tumors in the anterior mediastinum. Nevertheless, because the thymus originates in the third and fourth pharyngeal pouches and descends into the anterior mediastinum, ectopic thymic tissue may be found anywhere from the angle of the mandible to the superior mediastinum. Ectopic cervical thymoma (ECT) is an extremely rare tumor that originates from ectopic thymic tissue trapped during the migration of the embryonic thymus and is often misdiagnosed as a thyroid tumor or other neck masses. Herein, we report an unusual case of ectopic cervical thymoma associated to myasthenia gravis (MG).

A Recurrence Predictive Model for Thymic Tumors and Its Implication for Postoperative Management: a Chinese Alliance for Research in Thymomas Database Study

OBJECTIVE

Our aim was to investigate appropriate postoperative management based on the risk of disease recurrence in thymic epithelial tumors after complete resection.

METHODS

The Chinese Alliance for Research in Thymomas retrospective database was reviewed. Patients having stage I to IIIa tumors without pretreatment and with complete resection were included. Clinicopathologic variables with statistical significance in the multivariate Cox regression were incorporated into a nomogram for building a recurrence predictive model.

RESULTS

A total of 907 cases, including 802 thymomas, 88 thymic carcinomas, and 17 neuroendocrine tumors, were retrieved between 1994 and 2012. With a median follow-up of 52 months, the 10-year overall survival rate was 89.5%. Distant and/or locoregional recurrences were noted in 53 patients (5.8%). The nomogram model revealed histologic type and T stage as independent predictive factors for recurrence, with a bootstrap-corrected C-index of 0.86. On the basis of this model, patients with T1 thymomas or T2 or T3 type A, AB, or B1 thymomas had a significantly lower incidence of recurrence (low-risk group) than those with T2 or T3 type B2 or B3 thymomas and all thymic carcinomas and neuroendocrine tumors (high-risk group) (2.7% versus 20.1% [p < 0.001]). In the high-risk group, more than half of the recurrences (55.2% [16 of 29]) were seen within the first 3 postoperative years, whereas all recurrences but one were recorded within 6 years after surgery. Recurrence occurred quite evenly over 10 postoperative years in the low-risk group.

CONCLUSIONS

A 6-year active surveillance should be considered in high-risk patients regardless of adjuvant therapy. For low-risk patients, annual follow-up may be sufficient. Studies examining postoperative adjuvant therapies would be plausible in high-risk patients.

Clinical Outcomes of Up-front Surgery Versus Surgery After Induction Chemotherapy for Thymoma and Thymic Carcinoma: A Retrospective Study

INTRODUCTION

Although induction chemotherapy improves the resectability of thymic neoplasms, it is unclear whether surgery after induction chemotherapy can improve outcomes. We compared long-term outcomes of surgery with and without induction chemotherapy in patients with thymic neoplasms.

PATIENTS AND METHODS

We retrospectively investigated the clinical information of patients with thymic neoplasms at the National Taiwan University Hospital between 2005 and 2013.

RESULTS

Of 204 patients, 119 underwent direct surgery (group 1), 45 underwent surgery after induction chemotherapy (group 2), and 40 underwent no surgery (group 3). The 5-year overall survival rates of groups 1, 2, and 3 were as follows: for 204 patients, 96.3%, 76.4%, and 35.5% (P < .001); for 119 thymoma patients, 96.6%, 88.9%, and 100.0% (P = .835); for 85 thymic carcinoma patients, 94.7%, 69.7%, and 17.7% (P < .001); for 36 American Joint Committee on Cancer (AJCC) stage III-IVA thymoma patients, 92.9%, 83.3%, and 100% (P = .833); and for 28 stage III-IVA thymic carcinoma patients, 75.0%, 76.2%, and 62.5%, (P = .160). Univariate analysis showed that for group 2 (P = .0208) and group 3 (P < .0001), thymic carcinoma pathology type (P = .0010) and stage IVB disease (P < .0001) were poor prognostic factors. Multivariate analysis found thymic carcinoma (P = .0026) and stage IVB disease (P = .0449) to be poor prognostic factors.

CONCLUSION

Up-front surgery leads to best overall survival, and induction chemotherapy followed by surgery may improve resectability and outcomes. Only thymic carcinoma and stage IVB disease were poor prognostic factors in multivariate analysis.

Elective Nodal Irradiation as Adjuvant Radiotherapy for Advanced Thymomas and Thymic Carcinomas

INTRODUCTION

We evaluated the clinical outcome of patients with stage III to IV thymomas (Ts) or stage II to IV thymic carcinomas (TCs) treated with complete thymectomy and local radiation therapy (LRT, targeting the tumor bed and anterior mediastinal areas only) or elective nodal irradiation (ENI, targeting the entire mediastinal and supraclavicular regions).

MATERIALS AND METHODS

Data from 47 patients diagnosed with Ts or TCs and treated with surgery and adjuvant RT from May 2002 to May 2015 were analyzed. The standard RT dose was 50.4 Gy in 28 fractions; patients with a positive resection margin received a further 4 to 10 Gy. Survival outcomes determined at 5 years included local recurrence-free survival, regional recurrence-free survival, distant metastasis-free survival, and overall survival.

RESULTS

Five-year local recurrence-free survival was similar in both groups (LRT, 94.7% vs. ENI, 96.2%; P = .849). Significant differences were seen in 5-year regional recurrence-free survival (LRT, 55.1% vs. ENI, 83.7%; P = .006); however, tumor size was seen to be a significant factor (< 7 cm, 95.2% vs. ≥ 7 cm, 48.9%; P < .001), and the LRT group contained a greater proportion of patients with ≥ 7-cm tumors (70% vs. 33%). Multivariate analysis demonstrated that tumor size was the only significant prognostic factor (P < .001). No differences in 5-year overall survival were seen (LRT, 91.7% vs. ENI, 100%; P = .106).

CONCLUSION

ENI may not be indicated in all cases, as additional benefit in reducing recurrence or improving survival was not predominant. LRT seems to be a feasible option with favorable patient outcomes.

Value of Adjuvant Radiotherapy for Thymoma with Myasthenia Gravis after Extended Thymectomy

Background:

The co-existence of myasthenia gravis (MG) and thymoma makes the surgical treatment more complicated and adjuvant radiation more controversial. The aim of this study was to investigate adjuvant radiotherapy for thymoma with MG after extended thymectomy.

Methods:

A total of 181 patients with both MG and thymoma were recruited between 2003 and 2014 at Tongren Hospital, China. Among all the patients, 157 patients received radiation therapy after surgery (Group A); whereas the other 24 patients did not receive radiation therapy (Group B). According to the time that patients started mediastinal radiation therapy, we subdivided the 157 patients in Group A into subgroups (1-month subgroup, n = 98; 2-month subgroup, n = 7; and 3-month subgroup, n = 52). We then compared the effect of the mediastinal radiation therapy across these different groups using the survival rate, the rate of postoperative myasthenic crisis, and the complete stable remission (CSR) rate as the primary endpoints.

Results:

There was a significant difference in the occurrence of postoperative myasthenic crisis between 1-month subgroup and Group B (χ² = 4.631, P = 0.031). The rates of reaching CSR were 32.6% in 1-month subgroup, 25% in 3-month subgroup, and 22.7% in Group B, respectively. The overall survival rates of 1-month subgroup, 3-month subgroup, and Group B were 88.8%, 83.3%, and 77.3%, respectively. Analysis on the Kaplan-Meier survival curves demonstrated that within 8 years after surgery, there was no significant difference in aspects of overall survival and disease-free survival between 1-month subgroup and Group B, and between 3-month subgroup and Group B; over 8 years after surgery, the disease-free survival rates in 1-month subgroup, 3-month subgroup and Group B were 79.4%, 70.6%, and 55.3%, respectively.

Conclusions:

Adjuvant radiation within 1 month after extended thymectomy may be helpful in controlling postoperative MG, such as decreasing the possibility of postoperative myasthenic crisis, and raising cumulative probabilities of reaching CSR.

The expanding role of radiation therapy for thymic malignancies

The role of radiation therapy (RT) in thymic malignancies has long been subject to considerable controversy. The main role for RT is in the setting of adjuvant therapy after surgical tumor resection, especially in advanced or incompletely resected cases. However, recent studies with larger patient numbers and cleaner study populations than previous studies have indicated a potentially clearer than previously assumed benefit after post-operative RT (PORT) even for completely resected patients with earlier stages of thymoma. In marginally resectable patients RT may be used in combination with neoadjuvant chemotherapy to shrink tumors and thereby potentially enable resection. In unresectable patients concurrent or sequential chemotherapy and RT can be employed as the definitive nonsurgical approach. The tendency of thymic tumors to recur in the pleural space highlights the necessity for more effective approaches to identify and treat high risk patients. Experiences in other pleural malignancies may pave the way to novel treatment modalities, for example pleural IMRT. The role of these techniques in thymic malignancies has yet to be determined and is not advisable at the current time outside of a clinical study. As the disease often takes an indolent course with excellent long-term local control (LC) and survival, late toxicities related to radiation of the mediastinum and adjacent organs at risk (OARs) have to be taken into consideration and may jeopardize the benefit patients experience from RT, especially in younger patients with a long-anticipated life expectancy. Radiation techniques, such as intensity modulated RT (IMRT) and proton beam therapy (PBT), have substantially reduced the exposure of OARs to ionizing radiation which is expected to translate into reduced long-term toxicities. Hence, the risk-benefit ratio of RT in early stage thymoma patients may be shifted favorably.

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.

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.

Predicted Rate of Secondary Malignancies Following Adjuvant Proton Versus Photon Radiation Therapy for Thymoma

PURPOSE

Thymic malignancies are the most common tumors of the anterior mediastinum. The benefit of adjuvant radiation therapy for stage II disease remains controversial, and patients treated with adjuvant radiation therapy are at risk of late complications, including radiation-induced secondary malignant neoplasms (SMNs), that may reduce the overall benefit of treatment. We assess the risk of predicted SMNs following adjuvant proton radiation therapy compared with photon radiation therapy after resection of stage II thymic malignancies to determine whether proton therapy improves the risk-benefit ratio.

METHODS AND MATERIALS

Ten consecutive patients treated with double-scattered proton beam radiation therapy (DS-PBT) were prospectively enrolled in an institutional review board-approved proton registry study. All patients were treated with DS-PBT. Intensity modulated radiation therapy (IMRT) plans for comparison were generated. SMN risk was calculated based on organ equivalent dose.

RESULTS

Patients had a median age of 65 years (range, 25-77 years), and 60% were men. All patients had stage II disease, and many had close or positive margins (60%). The median dose was 50.4 Gy (range, 50.4-54.0 Gy) in 1.8-Gy relative biological effectiveness daily fractions. No differences in target coverage were seen with DS-PBT compared with IMRT plans. Significant reductions were seen in mean and volumetric lung, heart, and esophageal doses with DS-PBT compared with IMRT plans (all P≤.01). Significant reductions in SMNs in the lung, breast, esophagus, skin, and stomach were seen with DS-PBT compared with IMRT. For patients with thymoma diagnosed at the median national age, 5 excess secondary malignancies per 100 patients would be avoided by treating them with protons instead of photons.

CONCLUSIONS

Treatment with proton therapy can achieve comparable target coverage but significantly reduced doses to critical normal structures, which can lead to fewer predicted SMNs compared with IMRT. By decreasing expected late complications, proton therapy may improve the therapeutic ratio of adjuvant radiation therapy for patients with stage II thymic malignancies.

[Application of Postoperative Chemotherapy on Thymomas and Its Prognostic Effect]

背景与目的

探讨术后化疗在胸腺肿瘤中的应用及术后化疗对Masaoka Ⅲ期/Ⅳ期预后的影响。

方法

1994年3月至2012年12月, 中国胸腺瘤研究协作组(Chinese Alliance of Research for Thymomas, ChART)数据库共纳入2, 306例胸腺肿瘤病例, 资料相对完整1, 700例患者纳入本研究, 对其中Masaoka Ⅲ期/Ⅳ期665例患者进行进一步分析, 初步评估术后化疗的临床价值, 采用Kaplan-Meier法绘制不同亚组患者生存曲线, Cox回归进行多因素分析影响预后的因素。采用倾向值匹配研究(propensity-matched study, PSM), 评估化疗的临床价值。

结果

1, 700例患者中未行术后化疗1, 406例(82.7%), 术后化疗294例(17.3%), 随着Masaoka分期的增加, 术后化疗患者的比例也随之增高, 差异有统计学意义(P<0.001)。对Masaoka Ⅲ期/Ⅳ期患者665例进行进一步分析, 其中未术后化疗组444例, 术后化疗组221例。两组患者在有无重症肌无力、WHO病理类型、病理分期、手术根治性、有无术后放疗等方面分布有差异(P<0.05)。其中C型胸腺瘤、不完全切除和术后放疗明显影响患者术后复发和生存(P<0.05)。术后化疗组5年和10年无病生存率分别为51%、30%, 5年和10年复发率分别为46%、68%, 而未术后化疗组5年和10年无病生存率分别为73%、58%。5年和10年复发率分别为26%、40%, 两组无病生存率和复发率均有明显统计学差异(P=0.001, P=0.001)。对有无重症肌无力, 病理类型, 病理分期, 手术根治性状态, 术后放疗等因素进行倾向值匹配筛选出其中158例未术后化疗和158例术后化疗共316例患者, 生存分析显示:未术后化疗组和术后化疗组两组5年生存率并无明显统计学差异(P=0.332)。

结论

病理学类型、手术的根治性和术后放疗是影响进展期胸腺肿瘤患者术后生存和复发的主要因素。术后化疗并未给Masaoka-Koga Ⅲ期/Ⅳ期胸腺瘤患者带来生存获益。

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.

The clinical features, diagnosis and management of recurrent thymoma

Thymoma is a disease with malignant potential, which has a recurrence rate after complete resection ranging from 5 to 50 %. Multiple studies on the risk factors, treatment or prognosis have been reported. Many of them are controversial, however. In this review, we summarized some accepted risk factors, means of diagnosis and different treatments of recurrent thymoma. The risk factors of recurrent thymoma haven’t been well-studied, and its management remains controversial. We reviewed the literatures and found some key points which should be noticed during the surgery of initial thymoma. Although reoperation should be taken into account preferentially, multimodal treatments are also available. The prognosis are also been discussed.

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.

[Perioperative Outcomes and Long-term Survival in Clinically Early-stage Thymic Malignancies: Video-assisted Thoracoscopic Thymectomy versus Open Approaches]

背景与目的

胸腔镜胸腺切除术相比开放手术治疗早期（Masaoka-Koga Ⅰ期或Ⅱ期）胸腺恶性肿瘤在理论上具有优势，然而尚未有研究报道其在长期生存率方面的差异。本研究基于中国胸腺肿瘤研究协作组（Chinese Alliance for Research in Thymomas, ChART）的数据库对此进行了研究。

方法

以数据库中1994年到2012年间的1, 117例早期（Masaoka-Koga Ⅰ期或Ⅱ期）胸腺恶性肿瘤患者为研究对象。其中241例行胸腔镜胸腺切除术，876例行开放手术。采用单因素分析比较两组的临床资料与围手术期结果方面的差异。采用多因素分析明确影响长期预后的相关因素。

结果

与开放手术组相比，胸腔镜组的全胸腺切除比例更高（80.5% vs 73.9%, P=0.028），根治性切除率更高（98.8% vs 88.7%, P < 0.000），而复发率更低（2.9% vs 16.0%, P < 0.001），5年无瘤生存率更高（92% vs 83%, P=0.011），而两组的5年生存率接近（92% vs 92%, P=0.15）。Cox比例风险模型分析显示WHO分型、Masaoka-Koga分期和术后辅助治疗是影响胸腺恶性肿瘤长期生存的独立因素。

结论

胸腔镜胸腺切除术是治疗早期胸腺恶性肿瘤安全有效的方法，与开放手术相比其围手术期效果更好，肿瘤学疗效一致。

[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。

Reduced Port Thoracoscopic Surgery for Mediastinal and Pleural Disease: Experiences in a Single Institution

The purpose of this study was to present our current experience with reduced port thoracoscopic surgery (RPTS) for the treatment of mediastinal and pleural disease and thereafter discuss its indications and technical challenges. A total of 11 patients underwent surgery by the RPTS approach for the following conditions: thymoma (n = 2), bronchogenic cyst (n = 2), metastatic pleural tumor, thymic cyst, solitary fibrous tumor, pulmonary sequestration, pericardial cyst, neurinoma, and malignant lymphoma (n = 1). An Endo Relief forceps (Hope Denshi Co, Ltd, Chiba, Japan) was used for three of the surgical procedures. The elements of the data set consisted of gender, age, duration of operation, drain placement, hospital stay, mass location, and mass size. The median surgical time was 45 min (range, 40-78 min). There were no intraoperative complications and no need for a second surgery to open additional ports. The duration until chest tube removal was 1 day for all the cases. The median hospital stay was 4 days (range, 3-6 days). The median mass size was 2.2 cm (range, 1.2-4.2 cm). The median length of skin incision was 2.0 cm (range, 2.0-3.5 cm). In conclusion, RPTS for mediastinal and pleural disease may be a possible alternative approach to conventional multiportal video-assisted thoracoscopic surgery (VATS). Although it is technically plausible and feasible for selected cases, the issues of patient acceptability and cosmetic and oncological results remain to be determined in the future with randomized-controlled trials and long-term follow-up.

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.

Perioperative outcomes and long-term survival in clinically early-stage thymic malignancies: video-assisted thoracoscopic thymectomy versus open approaches

BACKGROUND

Video-assisted thoracoscopic surgery (VATS) theoretically offers advantages over open thymectomy for clinically early-stage (Masaoka-Koga stage I and II) thymic malignancies. However, long-term outcomes have not been well studied. We compared the postoperative outcomes and survival from a cohort study based on the database of the Chinese Alliance for Research in Thymomas (ChART).

METHODS

Between 1994 and 2012, data of 1,117 patients having surgery for clinically early-stage (Masaoka-Koga stage I and II) tumors were enrolled for the study. Among them, 241 cases underwent VATS thymectomy (VATS group), while 876 cases underwent open thymectomy (Open group). Univariate analyses were used to compare the clinical character and perioperative outcomes between the two groups. And multivariate analysis was performed to determine the independent predictive factors for long-term survival.

RESULTS

Compared with the Open group, the VATS group had higher percentage of total thymectomy (80.5% vs. 73.9%, P=0.028), resection rate (98.8% vs. 88.7%, P=0.000) and less recurrence (2.9% vs. 16.0%, P=0.000). Five-year overall survival was 92% after VATS and 92% after open thymectomy, with no significant difference between the two groups (P=0.15). However, 5-year disease free survival were 92% in VATS group and 83% in Open group (P=0.011). Cox proportional hazards model revealed that WHO classification, Masaoka-Koga stage and adjuvant therapy were independent predictive factors for overall survival, while surgical approach had no significant impact on long-term outcome.

CONCLUSIONS

This study suggests that VATS thymectomy is an effective approach for clinically early-stage thymic malignancies. And it may offer better perioperative outcomes, as well as equal oncological survival.

The application of postoperative chemotherapy in thymic tumors and its prognostic effect

BACKGROUND

To study the role of postoperative chemotherapy and its prognostic effect in Masaoka-Koga stage III and IV thymic tumors.

METHODS

Between 1994 and 2012, 1,700 patients with thymic tumors who underwent surgery without neoadjuvant therapy were enrolled for the study. Among them, 665 patients in Masaoka-Koga stage III and IV were further analyzed to evaluate the clinical value of postoperative chemotherapy. The Kaplan-Meier method was used to obtain the survival curve of the patients divided into different subgroups, and the Cox regression analysis was used to make multivariate analysis on the factors affecting prognosis. A Propensity-Matched Study was used to evaluate the clinical value of chemotherapy.

RESULTS

Two-hundred and twenty-one patients were treated with postoperative chemotherapy, while the rest 444 cases were not. The two groups showed significant differences (P<0.05) regarding the incidence of myasthenia gravis, World Health Organization (WHO) histological subtypes, pathological staging, resection status and the use of postoperative radiotherapy. WHO type C tumors, incomplete resection, and postoperative radiotherapy were significantly related to increased recurrence and worse survival (P<0.05). Five-year and 10-year disease free survivals (DFS) and recurrence rates in patients who underwent surgery followed by postoperative chemotherapy were 51% and 30%, 46% and 68%, comparing with 73% and 58%, 26% and 40% in patients who had no adjuvant chemotherapy after surgery (P=0.001, P=0.001, respectively). In propensity-matched study, 158 pairs of patients with or without postoperative chemotherapy (316 patients in total) were selected and compared accordingly. Similar 5-year survival rates were detected between the two groups (P=0.332).

CONCLUSIONS

Pathologically higher grade histology, incomplete resection, and postoperative radiotherapy were found to be associated with worse outcomes in advanced stage thymic tumors. At present, there is no evidence to show that postoperative chemotherapy may help improve prognosis in patients with Masaoka-Koga stage III and IV thymic tumors.

Clinical outcomes of CO2-less single-port video-assisted thoracoscopic thymectomy versus open thymectomy: comparative study

BACKGROUND

Although video-assisted thoracoscopic surgery (VATS) for thymic disorders has been introduced, its oncological outcome and benefits over others open approaches remains unclear. Single-port VATS thymectomy using a flexible port and CO₂ has been described. However, VATS thymectomy is possible by a single incision of 3 cm without CO₂ insufflation or special port device avoiding objections related to CO₂ insufflation and allowing instruments to move more freely making procedure easier and cheaper. Our institutional experience in open and CO₂-less VATS single-port thymectomy was retrospectively reviewed to evaluate compared to sternotomy, the clinical and oncological outcomes with this novel approach.

METHODS

A retrospective review consisting of 84 patients who underwent thymectomy because different thymic disorders especially thymoma was performed. Eighteen patients underwent CO₂-less VATS single port thymectomy, while 66 underwent thymectomy through open sternotomy. Many clinical factors associated with the surgical and clinical outcomes, including tumor recurrence and clinical remission, were recorded.

RESULTS

Non major postoperative complications were observed in any group. The median operative time and postoperative hospital stay of CO₂-less VATS single port thymectomy were 95 min and 1 day, respectively and 120 min and 7 days for open sternotomy. The thymoma was the most common thymic disorder with 7 patients (38%) in VATS group and 28 patients (42.4%) for the open approach. The median lesion size was 2.6 cm in the VATS group and 3.2 cm in the open approach. No thymoma recurrence in patients undergoing VATS was observed during the follow-up time, while in the open surgery group 14.28% recurrence was observed, distributed as follows: loco-regional 75% and 25% at distance; free disease period of these patients was 8.3 months. Thymectomy associated with myasthenia gravis (MG) was observed in 6 (33%) patients in the VATS group and 32 (48%) patients for sternotomy; our results regarding thymectomy for the treatment of MG were established by the MG post-intervention status [complete stable remission (CSR), pharmacologic remission, minimal manifestations, improved, unchanged and worse exacerbation, and died of MG] and reflected similar results in both approaches.

CONCLUSIONS

CO₂-less VATS single-port thymectomy is a feasible and safe procedure. Oncologic outcomes are similar to open approaches. Complications, surgical time and hospital stay are shorter compared with sternotomy. This is an initial experience, further work is required to evaluate long-term results.

The role of adjuvant chemotherapy following resection of early stage thymoma

BACKGROUND

There is a paucity of data regarding adjuvant chemotherapy for resected early stage thymoma. This systematic review was designed to investigate the effect of adjuvant chemotherapy on outcomes in patients with early stage thymomas.

METHODS

PubMed database was queried for studies containing information on adjuvant chemotherapy following surgery in patients with Masaoka stage I or II thymoma.

RESULTS

Eight retrospective observational studies were reviewed. The number of patients with stage I or II thymoma was not clearly reported in several studies. Five studies reported on 890 patients with stage I or II patients, including 140 patients (15.7%) who received adjuvant chemotherapy with or without radiotherapy. No study reported short-term mortality in patients undergoing adjuvant chemotherapy following thymectomy.

CONCLUSIONS

Adjuvant chemotherapy following resection of early thymomas appears to be a safe approach with favorable short-term outcomes. However, long-term outcomes remain unclear. There is no strong evidence to support adjuvant chemotherapy following resection of early-stage thymoma.

Prospective study of proton beam radiation therapy for adjuvant and definitive treatment of thymoma and thymic carcinoma: Early response and toxicity assessment

BACKGROUND AND PURPOSE

Radiation is an important modality in treatment of thymic tumors. However, toxicity may reduce its overall benefit. We hypothesized that double-scattering proton beam therapy (DS-PT) can achieve excellent local control with limited toxicity in patients with thymic malignancies.

METHODS AND MATERIALS

Patients with thymoma or thymic carcinoma treated with DS-PT between 2011 and 2015 were prospectively analyzed for toxicity and patterns of failure on an IRB-approved study.

RESULTS

Twenty-seven consecutive patients were evaluated. Patients were a median of 56 years and had thymoma (85%). They were treated with definitive (22%), salvage (15%) or adjuvant (63%) DS-PT to a median of 61.2/1.8 Gy [CGE]. No patient experienced grade ⩾3 toxicity. Acute grade 2 toxicities included dermatitis (37%), fatigue (11%), esophagitis (7%), and pneumonitis (4%). Late grade 2 toxicity was limited to a single patient with chronic dyspnea. At a median follow-up of 2 years, 100% local control was achieved. Three-year regional control, distant control, and overall survival rates were 96% (95% CI 76-99%), 74% (95% CI 41-90%), and 94% (95% CI 63-99%), respectively.

CONCLUSIONS

This is the first cohort and prospective series of proton therapy to treat thymic tumors, demonstrating low rates of early toxicity and excellent initial outcomes.

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.

Feasibility of thoracoscopic thymectomy for treatment of early-stage thymoma

INTRODUCTION

The objective of this study was to evaluate the feasibility of thoracoscopic thymectomy (TT) for treatment of early-stage thymoma and to compare the outcomes with those after open thymectomy (OT).

METHODS

A retrospective review of 98 patients who underwent TT or OT of Masaoka stage I-II thymoma without thymic cancer between 1996 and 2013 was performed.

RESULTS

Thoracoscopic thymectomy was performed in 67 patients, and OT was performed in 31 patients. The intraoperative blood loss amounts differed significantly between the TT group and OT group (100 vs 185 mL, P = 0.0070). The postoperative hospital stay was significantly shorter in the TT group than in the OT group (4 vs 12 days, P < 0.0001). No patient in the TT group underwent conversion to open surgery, and no surgical complications, such as massive bleeding, were observed. Two patients experienced recurrence in the TT group during the median postoperative follow-up period of 65 months. No significant differences were found in the 5-year disease-free survival rates between the two groups. There were no significant differences in disease-free survival as classified by Masaoka stage, World Health Organization type, and the extent of resection of the thymus.

CONCLUSION

Our outcome showed that TT largely reduced the degree of invasiveness. The outcome was not inferior to that of OT. The results primarily demonstrated the feasibility of TT for treatment of early-stage thymoma.

A Review of the Place and Role of Radiotherapy in Thymoma

Thymomas, tumors that arise from the epithelial cells of the thymus gland, are the most common tumors of the anterior mediastinum despite their overall rarity. They are not classified together with malignancies although it is recognized that they can be invasive and persistent even after attempted treatment. Because of their rarity, optimal treatment protocols remain a challenging topic. Although surgery is recognized as the cornerstone of management, the role and benefit of use of postoperative radiotherapy (PORT), remains questionable. Unequivocal evidence, although exclusively from retrospective studies, indicates that stage I thymoma is adequately treated with complete resection alone. As for stage II there is still a need to better determine the indications of PORT. For stage III and IV, existing data point to the fact that PORT plays a significant role in the management of thymoma. In patients for whom radiotherapy (RT) is indicated, 50 Gy appears to be adequate for microscopic disease and higher doses should be used for macroscopic tumor. With advances in RT delivery techniques, which allow for higher doses to be delivered to larger areas affected by tumor while sparing normal tissue, it is prudent to identify a place for this modality in the optimal management of thymoma patients.

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.

Radiotherapy for thymic carcinoma: adjuvant, inductive, and definitive

Although historically thymoma and thymic carcinoma have been treated surgically, radiation therapy also has an important role, either as postoperative therapy to reduce the risk of mediastinal recurrence or as part of definitive treatment for patients who cannot undergo surgery. Induction chemotherapy and molecular targeted agents may also be appropriate for thymic carcinoma, the behavior of which resembles non-small-cell lung carcinoma more than that of thymoma or invasive thymoma and is increasingly being treated like lung cancer. We present here a review of current therapies for thymic malignancies and briefly discuss the potential benefits from novel technologies for such treatment.

Oncological outcomes of thoracoscopic thymectomy for the treatment of stages I-III thymomas

OBJECTIVES

Thoracoscopic thymectomy has gradually replaced conventional sternotomy for resection of thymoma; however, a thoracoscopic approach for thymoma remains controversial. We evaluated the oncological outcomes of thoracoscopic thymectomy for the treatment of stages I-III thymomas.

METHODS

Sixty-two patients who underwent thoracoscopic thymectomy for the treatment of thymoma were retrospectively reviewed between July 2005 and September 2011 at Jikei University Hospital. Surgical outcomes and pathological results between stages I+II and stage III were compared.

RESULTS

Twenty-nine patients had Masaoka stage I, 28 had stage II and 5 had stage III. Three stage III patients needed conversions to open surgery. Masaoka stage III comprised pathological type B3 in 3 patients and thymic carcinoma in 2. For all patients, the 5-year overall survival rate was 100%. Three recurrences, diagnosed as thymic carcinoma, were observed in the Masaoka stage II or III patients. The 5-year disease-free survival rate was 94.2% for all patients, 100% for Masaoka stage I, 96.1% for stage II and 37.5% (55 months) for stage III (P=0.002). The 5-year disease-free survival rate was 100% for the World Health Organization classification types A, AB and B1-3 and 0% for thymic carcinoma (P<0.0001). Significant differences were found in the 5-year disease-free survival stratified by the Masaoka stage or WHO classification, but not by surgical procedures.

CONCLUSIONS

Thoracoscopic thymectomy for Masaoka stages I and II thymomas presented acceptable oncological outcomes. Further investigation in a large series with longer follow-up is required. Masaoka stage III thymoma requires careful consideration of the approaches, including median sternotomy.