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.     

Lymphogenous and hematogenous metastasis of thymic epithelial tumors

BACKGROUND: A TNM classification has been established for various tumors. However, the TNM classification of thymic epithelial tumor has not been established yet. METHODS: We received replies to a questionnaire on thymic epithelial tumors from 115 institutes. We compiled a database of 1,320 patients with thymic epithelial tumor (1,093 thymomas, 186 thymic carcinomas, and 41 thymic carcinoids) who were treated between 1990 and 1994. We used a tentative TNM classification of thymoma presented by Yamakawa and associates in 1991. The regional lymph nodes of the thymus were classified into three groups: anterior mediastinal lymph nodes (N1), intrathoracic lymph nodes (N2), and extrathoracic lymph nodes (N3). RESULTS: The rate of lymphogenous metastasis in thymoma, thymic carcinoma, and thymic carcinoid was 1.8%, 27%, and 28%, respectively. Most tumors with lymph node metastasis metastasized to N1 (thymoma, 90%; thymic carcinoma, 69%; thymic carcinoid, 91%). The 5-year survival rates of N0, N1, and N2 thymoma were 96%, 62%, and 20%, respectively. The 5-year survival rates of N0, N1(,) N2, and N3 thymic carcinoma were 56%, 42%, 29%, and 19%, respectively. The 5-year survival rates of M0 and M1 thymoma were 95% and 57%. The 5-year survival rates of M0 and M1 thymic carcinoma were 51% and 35%. Multivariate analysis demonstrated that survival of patients with thymoma was dependent on the clinical stage of Masaoka and complete resection. In thymic carcinoma, survival was dependent on lymph node metastasis and complete resection. CONCLUSIONS: The N factor was one of the predictors of survival in thymoma and thymic carcinoma. However, M factor showed less influence on survival than T or N factors.     

Long-term outcome after multimodality treatment for stage III thymic tumors

BACKGROUND: Surgery remains the cornerstone of therapy for thymic tumors, but the optimal treatment for advanced, infiltrative lesions is still controversial. The introduction of multimodality protocols has substantially modified survival and recurrence rate. We reviewed our 13-year prospective experience with multimodality treatment of stage III thymoma and thymic carcinoma. METHODS: Since 1989 we have prospectively used a multimodality approach in 45 stage III thymic tumors. Sixteen patients (35%) had myasthenia gravis. Twenty-three patients (51%) had pure or predominantly cortical thymoma (group 1), 11 (24.5%) had well-differentiated thymic carcinoma (group 2), and 11 (24.5%) had thymic carcinoma (group 3). Tumors that were not considered radically resectable at preoperative workup underwent biopsy and induction chemotherapy (15 patients, 33%) followed by surgical resection; all patients were referred for adjuvant chemoradiotherapy. RESULTS: No operative mortality was recorded; 1 treatment-related death during adjuvant chemotherapy was observed in group 1. Complete resection was feasible in 91% of patients in groups 1 and 2 and 82% in group 3. The overall 10-year survival was 78%. Ten-year survival for groups 1 and 2 was 90% and 85%, respectively; 8-year survival for group 3 was 56%. During follow-up, tumor recurrence was noted in 3 patients (13%) from group 1, 3 (27%) from group 2, and 3 (27%) from group 3. CONCLUSIONS: Multimodality treatment with induction chemotherapy (when required) and adjuvant chemoradiotherapy offers encouraging results for stage III thymic tumors; the outcome is more favorable for cortical thymoma and well-differentiated thymic carcinoma.     

Clinicopathologic assessment of primary thymic carcinoma based on seven cases

In order to study clinicopathologic characteristics of thymic carcinomas, seven patients experienced in our department were reviewed in this paper; 6 patients underwent thoracotomy and one did not receive surgical treatment. Among 6 who received operation, the tumor was resected totally in 3, subtotally in one, partially in one. One patient underwent exploratory thoracotomy. There have been no distinctive clinical features including clinical symptoms and radiographical findings from invasive thymomas in 7 primary thymic carcinomas, however, in these malignant tumors there have been no tumor-associated disorders not infrequently observed in thymomas. Postoperatively, distant metastasis was common in patients with thymic carcinomas, even though the primary tumor was resected totally in the operation. However, one patient with squamous cell carcinoma of the thymus who underwent subtotal tumor resection followed by radiotherapy and chemotherapy are surviving over 6 years postoperatively. Intensive treatment including pre- and postoperative radiation, tumor resection and postoperative chemotherapy is absolutely necessary for thymic carcinoma. Histologically, there were 4 squamous cell carcinomas and 3 large cell carcinomas. One of 3 large cell carcinomas showed squamous cell differentiation histologically. Two of 4 squamous cell carcinomas demonstrated concomitant entity of residual thymus tissue as well as thymoma in one specimen. However, further studies are necessary to determine precise etiology and tumor characteristics of thymic carcinoma.     

Thymic carcinoid in association with MEN syndromes.

Although carcinoid tumors in association with multiple endocrine neoplasia syndrome (MEN) has been well described, thymic carcinoid in association with MEN is extremely rare (only 23 cases in the world literature). A patient with thymic carcinoid and MEN-I was treated with surgical resection and postoperative radiation therapy, which was later followed by subtotal parathyroidectomy for hyperparathyroidism. Four years later, a symptomatic recurrence of his thymic carcinoid was resected from below his right clavicle. Six years after his original operation, the patient came to the hospital with pancreatitis, and a 5 cm, distal, pancreatic metastasis was resected. He now has symptomatic paraspinal and pleural metastases and is receiving somatostatin. Review of the world's literature shows that the majority of patients with thymic carcinoid and MEN-I are men with an average age of 37 years. Their clinical course is indolent, and surgery represents the only means of cure. Adjuvant chemotherapy and radiation therapy confer no survival advantage. The surgical decision making involved in treating a patient with thymic carcinoid and hyperparathyroidism associated with MEN is also discussed.     

Thymic tumors

Thymic tumors include thymic carcinoma, which exhibit aggressive behavior, and thymomas, which manifest a more indolent course. Complete resection is the mainstay of treatment, and there appears to be little benefit to partial resection. Postoperative radiotherapy may be useful in incompletely resected patients. Preoperative chemotherapy appears to increase the rate of complete resection and survival of patients with a stage III or IVa thymoma and should strongly be considered in such cases.     

Analysis of surgical treatment of Masaoka stage III-IV thymic epithelial tumors

Objective

The purpose of this study is to elucidate the outcomes after surgical resection of Masaoka stage III-IV thymic epithelial tumors.

Methods

We retrospectively reviewed patients with Masaoka stage III-IV thymic epithelial tumor who underwent surgical resection from January 1995 to January 2017. The clinicopathological features, surgical procedures, and postoperative outcomes were investigated.

Results

Thirteen patients with thymoma and 18 patients with thymic carcinoma were assessed. The postoperative Masaoka stages were III/IVa/IVb?=?8/4/1 in thymoma and III/IVa/IVb?=?11/2/5 in thymic carcinoma. In patients with thymoma, the World Health Organization pathological subtypes were A/B1/B2/B3?=?2/1/4/6. We performed combined resection and reconstruction for brachiocephalic vein or superior vena cava in 3 patients with thymoma and 7 patients with thymic carcinoma. In all patients, the patency rate of the grafts was very low for the left brachiocephalic vein and well maintained for the right brachiocephalic vein. Macroscopically and pathologically complete resection was achieved in 11 and 6 patients with thymoma, respectively, and in 15 and 9 patients with thymic carcinoma, respectively. The 10-year survival rates were 85.7% in thymoma and 70.3% in thymic carcinoma. Postoperative recurrences were observed in 2 and 9 patients with thymoma and thymic carcinoma, respectively. Recurrences were observed within 5 and 10 years after surgery in 2 patients with thymoma and within 2 years in all patients with thymic carcinoma.

Conclusions

Patients with Masaoka stage III-IV thymic epithelial tumor showed relatively favorable long-term survival after surgical treatment. Therefore, aggressive surgical resection for complete resection may be a treatment option for these conditions.

     

Role of chemotherapy in the management of advanced thymic tumors

Chemotherapy has an important role in the treatment of advanced thymic tumors. Early stage tumors are successfully treated with surgery. Locally advanced tumors (Masaoka stage III and IVA) are often treated with combined modality treatment including surgery, radiation, and chemotherapy. For patients with curable thymic tumors, the ability to attain a complete resection is a critical prognostic factor. Locally advanced tumors have a relatively high risk of recurrence and decreased rates of long-term survival. A multimodality approach including induction chemotherapy and postoperative radiation therapy can improve complete resection rates and long-term outcomes. Thymic tumors are chemoresponsive with optimal responses achieved with cisplatin-based combination chemotherapy. Chemotherapy with radiation can result in long-term progression-free survival for patients with locally advanced disease who remain inoperable following induction therapy. Patients with disseminated (stage IVB) thymic tumors can also have significant disease response and palliation of symptoms when treated with chemotherapy. Octreotide and corticosteroids also have shown efficacy. For best results, it is important that thoracic surgeons, radiation oncologists, and medical oncologists work together to obtain the best local control of tumor and optimal treatment of metastases.     

The radiotherapeutic management of invasive thymomas.

The role of radiation therapy has been well established for selected patients with thymoma. Among patients with stage I tumors that have undergone a complete surgical excision, there is no indication for postoperative RT. There is also no need for postoperative RT for patients with completely excised stage II tumors when there is no transgression of the tumor through the thymic capsule. If there is transgression of the tumor through the capsule, postoperative RT is recommended even in the presence of complete surgical resection. For totally or partially resected stage III tumors, postoperative RT, to a total dose in excess of 50.4 Gy, is recommended. CT scan-based treatment planning is recommended for all of these indications. The role of preoperative RT is currently less certain. For bulky, unresectable tumors, preoperative chemotherapy and postoperative RT seem to be a promising trimodality approach. There also will be a need for preoperative RT among partial responders.     

Thymic carcinoma. Clinical institutional experience with 15 patients.

OBJECTIVE: We retrospectively evaluated 15 patients with thymic carcinoma treated with various modalities and investigated overall management of this disease. METHODS: From 1983 to 2003, we treated 15 patients with thymic carcinoma (12 squamous cell carcinomas, 2 undifferentiated carcinomas and one adenocarcinoma). According to Masaoka's staging system, they consisted of 2 at stage II, 5 at stage III, 4 at stage IVa and 4 at stage IVb. RESULTS: Ten patients were histologically diagnosed preoperatively, and 5 patients underwent an exploratory procedure under the diagnosis of thymoma or benign teratoma. Complete resection was performed in 9 patients (2 stage II, 5 stage III and 2 stage IVa), which included 4 patients who received induction therapy, 4 who received postoperative radiation therapy, and 1 who received postoperative chemotherapy. Six patients with unresectable tumors were treated by irradiation (40-60 Gy) with or without chemotherapy. The median survival was 13 months for patients without resection, and 57 months for patients with a complete resection. Total 3-year and 5-year survival rates were 51.9 and 39.0%, respectively. CONCLUSIONS: We concluded that a complete resection is mainstay of therapy when possible, but chemoradiation therapy being potential benefit in the management of thymic carcinoma. However, considering the high prevalence of advanced stage patients, to establish the effective regimen of induction therapy in the additional multicenter trials should be mandatory.     

Role of chemotherapy in malignant thymoma

Thymomas and thymic carcinomas, which are rare epithelial tumors arising from the thymus gland, are the most common tumors of the anterior mediastinum. Surgery is the principal treatment and is curative in early stage disease. Radiation therapy, either alone or in combination with chemotherapy, may be an option both in not completely and completely resected disease. Chemotherapy is offered to patients with locally advanced or metastatic thymoma and induces excellent responses race and prolonged survival.     

Clinical study of operated nine thymic carcinomas

Nine cases of thymic carcinoma (5 males and 4 females) were operated in our hospital between 1990 and 1998. These cases included 4 squamous cell carcinomas, 2 small cell carcinomas, 2 undifferentiated carcinomas and one adenocarcinoma. Preoperative chemotherapy were performed in 3 cases. All cases underwent median-sternotomy followed by mediastinal irradiation, 4 had total resection of the tumor, 2 had subtotal resection and 3 had exploratory thoracotomy followed by mediastinal irradiation. Adjuvant chemotherapy were administered in 4 cases and re-operation were performed in 2 cases. We applied Masaoka's clinical staging for thymoma, nine cases consisted of 6 stage III cases, 2 stage IV b cases and one stage IV a case. Within 2 years after operation, 3 cases (two complete resection cases and one exploratory thoracotomy case) were died of the carcinoma. However, two cases of squamous cell carcinoma have been alive more than 5 years after surgery followed by chemoradiation. The remaining 4 patients are alive either with or without the carcinoma after 7 to 28 months after operation. Thymic carcinoma is not so common mediastinal tumor but is expected to increase in the future. The treatment of thymic carcinoma remains a controversial matter and the survival is poor compared with invasive thymoma, but multimodal-therapy would contribute to improvement of the results in treatment for thymic carcinoma especially in squamous cell carcinoma.     

Analysis of flow cytometric nuclear DNA content of the thymoma and its relationship to malignant intensity

Determination was made of the nuclear DNA content of paraffin-embedded specimens of resected thymoma using flow cytometry in 39 patients. Relationships among nuclear DNA content, clinicopathological findings and prognosis were studied. The frequency of DNA aneuploid tumors was 30.8%, 6.7% in stage I (15 patients), 28.6% in stage II (7 patients), 44% in stage III (9 patients) and 62.5% in stage IV (8 patients) according to Masaoka's classification, indicating more in increase with advancing stage and significant (p less than 0.05) more increase invasive thymoma than in noninvasive thymoma. The 5 year and 10 year survival rates of DNA diploid tumors were each 94%, while DNA aneuploid tumors, 75% and 45%. Patients with DNA aneuploid tumors showed less favorable prognosis than those with DNA diploid tumors. Similar results were found in patients with invasive thymoma and in those on whom subtotal or partial resection were performed. The present results indicate DNA aneuploid tumors to have greater malignant intensity than DNA diploid tumors in resected thymoma. Flow cytometric nuclear DNA content analysis provides useful biological data and new indices for evaluating the malignancy of resected thymoma.     

The usefulness of induction chemotherapy in cases with tumors showing border-line pathological aspects between thymoma and thymic carcinoma

We present 2 surgically treated cases with thymoma classified as Masaoka stage III and IV a (type B 3 thymoma), which showed the border-line pathological aspects between the thymoma and thymic carcinoma. Induction chemotherapy [CAV-PVP (cyclophosphamide, adriamycin, vincristine sulfate, etoposide) therapy in one case and ADOC (adriamycin, cisplatin, vincristine sulfate, cyclophosphamide) therapy in another case] preluded their surgical resection resulted in reduction of the tumor's size moderately or severely. After achievement of induction chemotherapy, these tumors were resected with the midsternotomy approach, along with resection of the right upper lobe and the left brachiocephalic vein replacing the expanded pdytetrafluoroethylene (ePTFE) graft following mediastinal lymphnodes dissection in one case and leaving the tumor tissue around the pulmonary trunk in another case. Postoperative irradiation of 40 Gy in one case and 60 Gy in another case were performed in the mediastinal regions. From pathological aspects especially in second case, though the specimen by preoperative needle biopsy stained positive for bcl-2 and strong immunoreactivity (20%) for MIB-1, specimens excised operatively after induction chemotherapy showed negative staining for bcl-2 and little staining (lower than 5%) for MIB-1. This fact indicates that the induction chemotherapy makes the tumor less malignant, in other words, from the face of thymic carcinoma to the face of thymoma. Induction chemotherapy performed for the purpose of reducing the tumor size was very advantage in these 2 cases with type B 3 thymoma.     

Chemotherapy for thymic tumors: induction, consolidation, palliation

Although thymoma and thymic carcinoma are rare malignancies, they constitute a large proportion of tumors of the anterior mediastinum. Surgery forms the mainstay of therapy; however, thymic malignancies are sensitive to chemotherapy and radiation therapy also. Systemic chemotherapy is primarily used for treatment of metastatic or recurrent disease. Chemotherapy is also used as a component of multimodality treatment in the neoadjuvant setting with the aim of increasing the chances of achieving a complete surgical resection. In this article we outline various clinical trials that have been performed to evaluate the role of chemotherapy in the treatment of thymic malignancies.     

Thymoma: results with complete resection and adjuvant postoperative irradiation in 141 consecutive patients

A series of 141 patients with thymoma was studied with regard to the way in which complete resection followed by postoperative radiation therapy influenced prognosis according to the stage and histologic type of thymoma. Postoperative radiation therapy (30 Gy in 3 weeks to 50 Gy in 6 weeks) was performed in 73.1% of the patients. Thirty-five of 48 patients with thymoma invading the surrounding tissues (stage III) underwent complete resection, with survival rates of 100% at 5 years and 94.7% at 10 and 15 years. The prognosis in these patients was comparable with those in 45 patients with no invasion (stage I) and in 33 patients with capsular invasion (stage III), all of whom underwent complete resection. Complete resection was done in 18 of 26 patients with epithelial cell thymoma, and there were no deaths by tumor until 15 years after the operation. There were no statistically significant differences in the survival rates of patients undergoing complete resection according to cell type (33 of 36 patients with lymphocyte predominant type and 61 of 77 patients with mixed cell type). The survival rate in six patients with epithelial cell type who underwent subtotal resection was not significantly different from that of 12 patients who underwent biopsy alone. Our findings indicate that complete resection of thymoma followed by postoperative radiation therapy results in a "benign" postoperative course, regardless of the stage and histologic type. Therefore, an aggressive surgical approach, such as resection of the superior vena caval system followed by reconstruction with a ringed polytetrafluoroethylene graft and/or complete pleuropneumonectomy, is justified for advanced thymoma, although the long-term results of such extended operations are still unclear.     

Thymoma and thymic carcinoma

Thymic tumors comprise a heterogeneous group of neoplasms with a wide spectrum of clinical presentations. The evolution of the disease is often unpredictable, ranging from an indolent attitude to the possibility of intra- and extrathoracic spread. From the histological point of view, thymoma and thymic carcinoma are the most frequent subtypes and arise only from thymic epithelial cells. Other histological types are even more rare and are usually considered separately. A number of prognostic factors have been validated as predictors of outcome: staging, World Health Organization histological classification, diameter of the tumor, associated paraneoplastic syndromes, completeness of resection, and early onset of recurrence. Complete surgical resection is the key factor for cure and should be considered the gold standard at any stage. Especially for more aggressive lesions, surgery should be considered with a multimodality approach, involving induction and adjuvant therapy according to the stage. Multimodality therapy protocols have been designed based on the integration of clinical staging and histology. Neoadjuvant therapy is now administered before surgical resection in patients with tumors considered inoperable as it improves resectability and survival and reduces the risk of recurrence. Adjuvant treatment has been extensively reported after both complete or partial resection. New targeted therapies are in the developmental stage, and in the future they will be part of the standard protocols. Integrated treatment modalities require strict cooperation between medical and radiation oncologists, thoracic surgeons, and pathologists.     

Synchronous B3 thymoma and lung bronchoalveolar carcinoma

The association between thymic tumors and other intrathoracic or extrathoracic neoplasms is relatively rare; the synchronous occurrence of thymoma and bronchoalveolar carcinoma of the lung has never been described so far. A huge B3 cystic thymoma was found at thoracotomy to be associated with stage IV bronchoalveolar carcinoma (intraparenchymal and pleural metastases). The thymic tumor was completely resected; lung cancer was biopsied only for diagnosis and staging purposes. After an uneventful postoperative course the patient underwent chemotherapy; she is still alive and well one year after surgery.     

Which stages of thymoma benefit from adjuvant chemotherapy post-thymectomy?

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was 'Which stages of thymoma benefit from adjuvant chemotherapy post thymectomy?' Altogether more than 150 papers were found using the reported search, of which only eight represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated; these studies have mainly reported the survival and recurrence rates of post-thymectomy patients who received adjuvant radiotherapy or chemoradiotherapy, and adjuvant radiotherapy alone was only used in a small group of patients in these studies. We did not find any randomized controlled trials comparing adjuvant chemotherapy with chemo/radiotherapy and, due to a very small incidence of this tumour, it is unlikely to see any trials in future. Studies were mainly retrospective or institutional reports and showed that, despite the high sensitivity of this tumour to chemotherapy agents and the use of chemotherapy as one of the main treatment modalities in the advanced stages of thymoma, current data are not supporting postoperative chemotherapy as a sole adjuvant treatment in advanced stages of thymoma. We conclude that, in patients with thymoma, surgical resection with or without radiation therapy is the gold standard treatment for early-stage disease (I and II). Adjuvant radiotherapy/chemoradiotherapy should be considered for Masaoka stage III (A and B) or above, and it is also advised to add adjuvant therapy for all patients with cortical fenestration, even in stages I and II. But there is no evidence that chemotherapy alone improves the survival in patients with completely resected stage III and IV thymomas and thymic carcinoma. In patients with extra-radiation field disease, however, the use of chemotherapy can potentially improve survival but no follow-up data on this group of patients are available.     

Stage IVA thymoma: patterns of spread and surgical management

Stage IVA disease can be de novo disease or more commonly represent recurrent disease. The pleura is the most common site of relapse after thymoma resection. Local pleural disease is usually simply resected. This is usually combined with either induction or adjuvant chemotherapy. The ultimate extended surgery for advanced thymic tumors is an extrapleural pneumonectomy done for extensive pleural disease. This rarely performed operation is done for both stage IVA disease found at initial presentation and for recurrent disease as a salvage procedure. Again, these advanced patients with pleural spread are probably best managed by induction chemotherapy followed by resection.