Role of radiation therapy in locally advanced thymoma

Intensity Modulated Radiation Therapy Plus Etoposide/Cisplatin for Patients With Limited Advanced Unresectable Thymic Epithelial Tumors: A Prospective Phase 2 Study

PURPOSE

This prospective phase 2 study evaluated the efficacy and safety of intensity modulated radiation therapy plus etoposide/cisplatin (EP) for patients with unresectable thymic epithelial tumors (TETs).

METHODS AND MATERIALS

Patients with limited advanced unresectable TETs whose lesions could be encompassed within radiation fields were enrolled in this study. Two cycles of EP (75 mg/m² etoposide and 25 mg/m² cisplatin on days 1-3 and days 29-31) were administered concurrently with radiation therapy, followed by 2 cycles after radiation therapy. The primary endpoint was the objective response rate. The secondary endpoints were the progression-free survival rate, overall survival rate, and incidence of adverse events.

RESULTS

Fifty-six patients were enrolled between June 2011 and May 2018. Twenty-two and 34 patients had thymomas and thymic carcinomas, respectively. The median age was 52 (range, 21-76) years, and 30 patients (53.6%) were men. Eight patients (14.3%) had stage III tumors, 6 (10.7%) had stage IVA tumors, and 42 (75.0%) had stage IVB tumors. The objective response rate was 85.7% (95% confidence interval, 76.3%-95.2%). With a median follow-up of 46 (range, 7-101) months, the 1-, 2-, and 5-year progression-free survival rates were 66.1%, 48.0%, and 29.5%, and the 1-, 2-, and 5-year overall survival rates were 91.0%, 76.2%, and 56.2%, respectively. The most common grade 3 to 4 adverse event was leukopenia (42.9%). Pulmonary fibrosis was also observed (5.3%).

CONCLUSIONS

Because intensity modulated radiation therapy with EP is effective and safe for limited advanced unresectable TETs, it could be a suitable treatment option for such patients.

Prospective Study of Stereotactic Body Radiation Therapy for Thymoma and Thymic Carcinoma: Therapeutic Effect and Toxicity Assessment

Stereotactic body radiation therapy (SBRT) is an important modality in treatment of tumors. We hypothesized that SBRT can achieve excellent local control with limited toxicity in patients with thymic tumors. A single-institution prospective study was performed with 32 patients who underwent SBRT of thymoma and thymic carcinoma between 2005 and 2014. Thirty-two patients including 39 target lesions were analyses in this study. Almost half of the patients (46.9%) were type C by histopathology and more than half (56.3%) were classified into stage IVA or IVB. The median dose of SBRT for gross tumor volume (GTV) was 56 Gy (range 49–70 Gy). Results showed that the response rate was 96.9% after SBRT and the median tumor shrinkage rate was 62.2% (range 3.8–100%). For the patients with both stage II–III and type A-B (n = 6), the median PFS was 28 months. In-field failure was only observed in 4 patients, and outside-field failure was seen in 2 patients. The local control rate was 81.25%. Patients treated with SBRT had an excellent local control with mild toxicities, which suggests that SBRT is feasible for the patients with thymic tumors who are unable to undergo either surgery or conventionally fractionated radiation therapy.

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.

Thymic neoplasm: a rare disease with a complex clinical presentation

Thymic neoplasms constitute a broad category of rare lesions with a wide spectrum of pathologic characteristics and clinical presentations which therefore require a high index of suspicion to diagnose. The natural history of the disease is seldom predictable, anywhere from an indolent to an aggressively malignant course. Although the classification and staging of these lesions are complex and controversial, complete radical surgical resection remains the gold standard of therapy. Radiation and chemotherapy are important elements of the multimodality approach to treating these patients and it is important for thoracic surgeons to work closely with their colleagues in other disciplines in the management of and future research endeavors in thymic neoplasm. In this review, we discuss the evaluation of the patient with an anterior mediastinal mass, the classification and staging of thymic neoplasms, the role of surgery, radiation and chemotherapy in treating this disease, as well as future directions in research for novel targeted therapies.

Does surgical debulking for advanced stages of thymoma improve survival?

A best evidence topic in cardiothoracic surgery was written according to a structured protocol. The question addressed was 'Does surgical debulking for advanced stages of thymoma improve survival?' Altogether, only 17 papers were found using the reported search, of which only 10 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 after total vs subtotal resection of thymic tumours in patients receiving or not receiving adjuvant chemoradiotherapy. These studies confirmed that complete resection is the best prognostic factor in thymomas. With regard to subtotal tumour resection/debulking, we did not find any randomized controlled trials. The evidence on this topic is scarce and these 10 reported were retrospective reviews of the operative, histology and survival data of patients with thymoma who had subtotal vs partial resection for advanced stages of thymoma. Although debulking surgery for thymoma had positively affected survival, in six studies, the difference failed to reach statistical significance. Three of the studies, on the other hand, showed a higher survival rate in thymomas in which maximum debulking was performed and the treatment was followed by high-dose irradiation. None of these studies showed any benefit in debulking surgery for thymic carcinoma. Besides histology and tumour cell-type, other factors influencing survival included the tumour stage and the presence of symptoms such as myasthenia gravis as a warning sign at an early stage. Current evidence in the literature on the survival after debulking surgery for thymoma is contradictory, and most of the studies do not show any survival benefit after debulking for thymoma. However, debulking surgery minimizes the tumour size and area for irradiation postoperatively, hence it can result in less damage to the adjacent tissue during radiotherapy and may be considered for patients in advanced stages of thymoma in whom extensive radiotherapy will be required. In these cases, however, the risks of surgery followed by radiotherapy or radiotherapy alone should carefully be assessed prior to the initiation of treatment.

Surgical management of stage III thymic tumors

Thymic tumors are classified as stage III when they clearly invade the surrounding structures: pericardium, great vessels (superior vena cava, innominate veins, ascending aorta, and main pulmonary artery), lung parenchyma, phrenic nerves, and chest wall. Surgical treatment with or without induction therapy should always aim to complete resection removing en bloc all the involved structures. Also, extended procedures are justified because only R0 resection allows long-term survival.

Radiotherapy for thymic neoplasms. J Thorac Oncol. 2010;5:S327-S335. [PMID: 20859128 DOI: 10.1097/jto.0b013e3181f20ec4]

The role of radiotherapy in the treatment of thymoma and thymic carcinoma has been evaluated by many investigators over the past two decades. The low incidence of these neoplasms has limited most published studies to small series spanning long time intervals or population-based studies. The exact indications and protocols for the use of radiotherapy as a part of the multidisciplinary approach to thymoma and thymic carcinoma are still unclear. However, a review of recent literature shows potential benefits for certain patients based on stage and grade of disease as well as the extent of surgical resection.

A phase II trial of dose-dense chemotherapy, followed by surgical resection and/or thoracic radiotherapy, in locally advanced thymoma: report of a Japan Clinical Oncology Group trial (JCOG 9606)

BACKGROUND

This study aimed to evaluate the safety and efficacy of dose-dense weekly chemotherapy, followed by resection and/or thoracic radiotherapy.

METHODS

Patients with histologically documented thymoma with unresectable stage III disease received 9 weeks of chemotherapy: cisplatin 25 mg m(-2) on weeks 1-9; vincristine 1 mg m(-2) on weeks 1, 2, 4, 6 and 8; and doxorubicin 40 mg m(-2) and etoposide 80 mg m(-2) on days 1-3 of weeks 1, 3, 5, 7 and 9. Patients went on to surgery and post-operative radiotherapy of 48 Gy; those with unresectable disease received 60 Gy radiotherapy.

RESULTS

total of 23 patients were entered. The main toxicities of the chemotherapy regimen were neutropenia and anaemia, and 57% of patients completed the planned 9 weeks of therapy. There were no toxic deaths. Of the 21 eligible patients, 13 (62%) achieved a partial response (95% confidence interval: 38-82%). Thirteen patients underwent a thoracotomy and nine (39%) underwent complete resection. Progression-free survival at 2 and 5 years was 80 and 43%, respectively. Overall survival at 5 and 8 years was 85 and 69%, respectively. Survival did not seem to be affected by resection.

CONCLUSION

In thymoma patients, weekly dose-dense chemotherapy has activity similar to that of conventional regimens. Although some patients could achieve complete resection, the role of surgery remains unclear.

A phase-II trial of dose-dense chemotherapy in patients with disseminated thymoma: report of a Japan Clinical Oncology Group trial (JCOG 9605)

BACKGROUND

To evaluate the safety and efficacy of dose-dense weekly chemotherapy in the treatment of advanced thymoma.

METHODS

Subjects comprised patients with histologically documented chemotherapy-naïve thymoma with stage-IVa or IVb disease. Thymic carcinoma, carcinoid or lymphoma cases were excluded. Patients received 9 weeks of chemotherapy: cisplatin (25 mg m(-2)) on weeks 1-9; vincristine (1 mg m(-2)) on weeks 1, 2, 4, 6 and 8; and doxorubicin (40 mg m(-2)) and etoposide (80 mg m(-2)) on days 1-3 of weeks 1, 3, 5, 7 and 9. Chemotherapy courses were supported by granulocyte colony-stimulating factor. Post-protocol local therapy was allowed.

RESULTS

From July 1997 to March 2004, 30 patients were entered. Three were ineligible due to different histology. Chemotherapy-associated toxicity was mainly haematological and was well tolerated, with no deaths due to toxicity, and 87% of patients completed the planned 9-week regimen. Overall response rate was 59%, with 16 of the 27 eligible patients achieving partial response. Median progression-fee survival (PFS) was 0.79 years (95% confidence interval: 0.52-1.40 years), and PFS at 1 and 2 years was 37 and 15%, respectively. Overall survival rates at 2 and 5 years were 89 and 65%, respectively.

CONCLUSION

In stage-IV thymoma patients, weekly dose-dense chemotherapy offers similar activity to conventional regimens.

The potentials of proton beam radiation therapy in malignant lymphoma, thymoma and sarcoma

A group of Swedish oncologists and hospital physicists have estimated the number of patients in Sweden suitable for proton beam therapy. The estimations have been based on current statistics of tumour incidence, number of patients potentially eligible for radiation treatment, scientific support from clinical trials and model dose planning studies and knowledge of the dose-response relations of different tumours and normal tissues. Besides sarcomas of the base of skull, which are classical sites for proton beam therapy, it is estimated that about 40 patients yearly in Sweden with sarcomas at other sites are candidates for proton beam therapy. About 20 patients each with malignant lymphomas, chiefly in the mediastinum, and thymomas are also candidates to decrease doses to surrounding heart and lungs.

Postoperative radiotherapy after surgical resection of thymoma: differing roles in localized and regional disease

PURPOSE

To analyze the Surveillance, Epidemiology and End Results (SEER) registry data to determine the impact of postoperative radiotherapy (PORT) for thymoma and thymic carcinoma (T/TC).

METHODS AND MATERIALS

Patients with surgically resected localized (LOC) or regional (REG) malignant T/TC with or without PORT were analyzed for overall survival (OS) and cause-specific survival (CSS) by querying the SEER database from 1973-2005. Patients dying within the first 3 months after surgery were excluded. Kaplan-Meier and multivariate analyses with Cox proportional hazards were performed.

RESULTS

A total of 901 T/TC patients were identified (275 with LOC disease and 626 with REG disease). For all patients with LOC disease, PORT had no benefit and may adversely impact the 5-year CSS rate (91% vs. 98%, p = 0.03). For patients with REG disease, the 5-year OS rate was significantly improved by adding PORT (76% vs. 66% for surgery alone, p = 0.01), but the 5-year CSS rate was no better (91% vs. 86%, p = 0.12). No benefit was noted for PORT in REG disease after extirpative surgery (defined as radical or total thymectomy). On multivariate OS and CSS analysis, stage and age were independently correlated with survival. For multivariate CSS analysis, the outcome of PORT is significantly better for REG disease than for LOC disease (hazard ratio, 0.167; p = 0.001).

CONCLUSIONS

Our results from SEER show that PORT for T/TC had no advantage in patients with LOC disease (Masaoka Stage I), but a possible OS benefit of PORT in patients with REG disease (Masaoka Stage II-III) was found, especially after non-extirpative surgery. The role of PORT in T/TC needs further evaluation.

Optimal therapy for thymoma

Thymoma is the most common tumor of the anterior mediastinum. This tumor is associated with unique paraneoplastic syndromes (myasthenia gravis, pure red cell aplasia, hypogammaglobulinemia, and other autoimmune diseases). The rarity of this tumor has somewhat obscured the optimal treatment. Although the histologic classification of thymoma has remained a subject of controversy for many years, the WHO classification system, published in 1999, appeared to be an advance in our understanding of thymoma. The optimal treatment for thymoma depends on its clinical stage. Surgery remains the mainstay of treatment for thymic epithelial tumors. Thymomas also have a high response rate to chemotherapy or radiotherapy. Only surgical resection is performed for patients with stage I (non-invasive) thymoma. The value of postoperative radiotherapy in completely resected stage II or III tumors is questionable. Multimodality therapy involving surgery, chemotherapy and radiotherapy appears to increase the rate of complete resection and survival in advanced (stage III and IV) thymomas.

Primary intrapulmonary thymoma: A systematic review

AIM

This article reviews the literature on the clinical features, diagnosis and management of primary intrapulmonary thymoma.

METHODS

Medline, Embase and Cochrane Library searches were performed on all relevant Anglo-Saxon language articles. The search words included "primary pulmonary thymoma" and "intrapulmonary thymoma". Secondary references were obtained from key articles. Prognostic and treatment strategies were analyzed by the Kaplan-Meier method, comparisons between curves were made using log rank test.

RESULTS

The searches yielded 25 cases of primary intrapulmonary thymoma. Median follow-up was 9 months (1 day to 13 years). At follow-up, 14 patients were tumor free, one patient had a local recurrence 8 years after radiotherapy, one patient responded favorably to radiotherapy, six patients died and three patients were lost to follow-up. The presence of a paraneoplastic syndrome decreased survival (P=0.02), however, histological subgroup (P=0.216), clinical stage (P=0.63) and tumor size (P=0.288) did not affect survival. Survival in surgically managed patients was significantly better than in conservatively managed patients (P=0.039). Adjuvant radiotherapy did not provide any benefit (P=0.4).

CONCLUSION

Complete resection of primary intrapulmonary thymomas appears sufficient in non-malignant tumors. Because of the risk of late local recurrence, long-term regular clinical follow-up is warranted.

The Role of Radiation Therapy in Thoracic Tumors

Radiation plays an important role in the treatment of thoracic tumors. During the last 10 years there have been several major advances in thoracic RT including the incorporation of concurrent chemotherapy and the application of con-formal radiation-delivery techniques (eg, stereotactic RT, three-dimensional conformal RT, and intensity-modulated RT) that allow radiation dose escalation. Radiation as a local measure remains the definitive treatment of medically inoperable or surgically unresectable disease in NSCLC and part of a multimodality regimen for locally advanced NSCLC, limited stage SCLC, esophageal cancer, thymoma, and mesothelioma.

Tumeurs épithéliales thymiques

Thymomas and thymic carcinomas are rare and slow-growing tumors, which develop within the anterior mediastinum. Thymomas are often associated with autoimmune disorders and most particularly myasthenia gravis. The treatment of choice remains a complete surgical resection. Postoperative radiotherapy is often combined in case of invasive thymoma invading into adjacent organs. Postoperative radiotherapy in stage II with invasion into capsule has been more controversial lately. In inoperable locally advanced, or metastatic thymic tumors, neoadjuvant cisplatin-based followed by surgery and radiotherapy has given interesting results in the past years.

Current chemotherapy options for thymic epithelial neoplasms

Thymomas and thymic carcinoma are rare neoplasms. Surgical resection is the cornerstone of effective therapy. Stage I disease is effectively treated by complete surgical resection. The role of radiation therapy in completely resected stage II disease remains controversial. Adjuvant radiation therapy is useful for local control and may improve survival in patients with incompletely resected tumours. Cisplatin-based chemotherapy regimens play an important role in the treatment of advanced stage III/IV or recurrent disease thymomas, but have proven less effective for thymic carcinoma. Phase II trials of multimodality therapy incorporating neoadjuvant chemotherapy, surgery and postoperative radiation therapy show promise for unresectable disease. This review discusses recent clinical data and the potential role for agents targeting the epidermal growth factor receptor, angiogenesis and apoptotic pathways.

Treatment of recurrent thymic tumors

Surgery is the cornerstone of therapy for recurrent thymic tumors. The pattern of recurrence is, however, less defined. Between 1966 and 1988, we operated on 83 patients with thymoma, 11 of whom underwent surgery for recurrence (group I). In 1989, we initiated a prospective multimodality protocol and have enrolled 128 patients with 9 (7%) recurrences since (group II). In group I, 1 patient was originally at stage I, 2 were at stage II, 5 at stage III, and 3 at stage IV. The patients underwent 1 (#10) or 2 (#1) reoperations and 5 showed histological progression of malignancy. One patient died postoperatively, 6 died of disease, and 3 are alive and disease free 18 to 22 years after the first operation. In group 2, no patient was originally at stage I, 1 was at stage II, 4 were at stage III, and 4 at stage IV. Reoperation (5 patients) was followed by chemotherapy and 2 showed histological progression of disease. One patient died after 2 years, and 4 patients are alive after 6 to 11 years. All recurrent tumors were thymomas with cortical differentiation. Early onset of recurrence was a negative prognostic factor. Thymomas can recur also at early stages. A multimodality approach is indicated also for early stage lesions based on histology.

Radiation therapy in the management of thymic tumors

Thymic tumors including thymomas, thymic carcinomas, and thymic carcinoid tumors, are relatively infrequent. These tumors with a wide spectrum of histological and biological features may exhibit an indolent clinical course (thymomas) or manifest an aggressive behavior (thymic carcinoma) with a high risk of relapse and metastasis. Successful management of these tumors depends on accurate diagnosis, thorough staging, proper assessment of patient health status, and selection of treatment modality. Surgery remains the mainstay of therapy whereas radiation therapy plays an important role in subtotally resected or unresectable cases. The risk of side effects and late sequelae is generally low when proper radiation technique is employed. This review examines the current role of radiation therapy in the management of these tumors.

Transsternal thymoma resection

Thymomas are traditionally regarded as tumours arising from the epithelial cells of the thymus. They are the second most frequent mediastinal tumour in the adult and show a variable clinical presentation and clinical course. Complete surgical resection should be the gold standard. The preferred approach is complete median sternotomy and an extended thymectomy is usually performed. A multimodality approach should be considered for invasive lesions or tumours giving intrathoracic metastases.

Radiotherapy and prognostic factors for thymoma: A retrospective study of 175 patients

PURPOSE

To assess the factors that predict local control and survival in patients with thymoma treated with adjuvant radiotherapy (RT) and suggest strategies for optimizing adjuvant RT.

METHODS AND MATERIALS

The study population comprised 47 patients with noninvasive thymoma and 128 patients with invasive thymoma. Treatment was surgery in 175 patients and radiotherapy in 169 patients; 25 patients also received adjuvant chemotherapy. The clinical factors (age, histologic features, stage, presence of myasthenia gravis) and therapeutic factors (extent of operation, irradiation dose, and field size) were retrospectively recorded and accessed using multivariate analysis.

RESULTS

The overall survival rate at 5 and 10 years was 86.4% and 80.6%, respectively. Only 2 patients had a relapse in the noninvasive group. None died of thymoma during the study period. The patients with invasive disease had a 5- and 10-year disease-free survival rate of 64.4% and 55.6%, respectively, with 24 intrathoracic failures, 14 extrathoracic failures, and 8 combined failures. The univariate and multivariate analyses showed that Mosaoka stage and extent of resection were the important prognostic factors for patient with invasive thymoma. The 5-year survival rate and local control rate was 96% and 96% for Stage II, 77.8% and 56.4% for Stage III, 56.6% and 42.7% for Stage lVa, and 35.6% and 21.6% for Stage IVb (p < 0.0001 among different stage groups), respectively. The 5-year local control rate in patients with the tumor bed irradiated was 68.2%, comparable to the group treated with an extended RT field (66.6%). Age, histopathologic findings, radiation dose, and presence of myasthenia gravis were not statistically significant prognostic factors.

CONCLUSION

Disease stage and extent of resection affected the prognosis of invasive thymoma patients. Extending the radiation field prophylactically was not associated with greater local control and is of questionable value for patients with invasive thymoma.

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.

Multimodal management of stages III–IVa malignant thymoma

PURPOSE

The optimal therapy for locally advanced malignant thymoma is controversial. We review our experience with a multimodal approach in 63 consecutive cases.

PATIENTS AND METHODS

Forty-three patients had stage III and 20 stage IVa disease. Surgery with radical intent was initially performed in 30 cases, while 33 cases not amenable to radical surgery underwent neoadjuvant treatment (radiotherapy in 8 and chemotherapy in 25) before surgical reassessment. All patients, whether or not surgically resected, received radiation therapy.

RESULTS

Radical resection (RR) was performed in 20 patients ab initio (all stage III) and in 12 patients after neoadjuvant treatment (eight stage III and four stage IVa). With the addition of patients radically operated with neoadjuvant treatment, the radical resection rate increased from 46 to 65% in stage III patients, and from 0 to 20% in those with stage IVa disease, respectively. Radical surgery was associated with longer progression free survival and overall survival according to both univariate analysis ( P< 0.001 and P<0.01, respectively) and multivariate analysis after adjustment for age, gender, histology and disease stage ( P<0.001 and <0.02, respectively). Progression free survival (median 56.9 months) was slightly lower in patients undergoing radical surgery after neoadjuvant approaches than in those radically resected ab initio (median not achieved), but overall survival (median not achieved) was similar in both groups. Subtotal surgical resection promoted complete response to subsequent radiation therapy. This condition significantly correlated with a better outcome.

CONCLUSIONS

Complete surgical resection is an independent prognostic parameter in locally advanced thymoma treated with a multimodal approach. Preoperative treatment to increase the complete resection rate could improve the overall survival of these patients.

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

BACKGROUND

Adjuvant radiation after resection of Masaoka stage II thymoma is widely advocated, but the evidence supporting it is controversial. Studies addressing this issue generally report few patients and lump all patients beyond stage I together in the analysis.

METHODS

We retrospectively compared outcomes of stage I and II thymomas treated by resection alone with thymomas treated by resection plus radiation. Histology was re-reviewed to confirm pathologic staging and resection margin status.

RESULTS

Between February 1992 and 2002, we performed 167 resections for thymoma. Of these, 70 patients were believed to have tumors in stage IIb or less intraoperatively, and all of these patients underwent complete resection. We reviewed the histopathology of 62 of 70 patients. Thirty thymomas demonstrated less than complete transcapsular microscopic invasion (stage I) and 40 thymomas demonstrated microscopic transcapsular invasion or macroscopic invasion into surrounding fatty tissue (stage II). Forty-seven patients underwent surgery without postoperative mediastinal radiotherapy. Dosages in the 23 radiated patients (3 stage I and 20 stage II) consisted of 45 to 55 Gy. Median follow-up was 70.3 months. Stage II patients who were radiated (n = 20) and those who were not radiated (n = 20) consisted of identical proportions in stages IIa and IIb. Two patients recurred (1 unradiated stage I patient and 1 radiated stage IIb patient). Overall 5-year survival rate was 91%. All who died were free of recurrence at time of death. Log-rank test showed no difference in Kaplan Meier survival curves (p = 0.32) between the radiated and unradiated groups.

CONCLUSIONS

These data support the contention that margin-negative surgical resection alone is sufficient treatment for both stages I and II thymoma.

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.

Postoperative radiotherapy for patients with completely resected thymoma: a multi-institutional, retrospective review of 103 patients

BACKGROUND

Optimal management of postoperative radiotherapy for patients with completely resected thymoma remains controversial. This study was conducted to assess the efficacy of postoperative mediastinal irradiation in patients with completely resected thymoma.

METHODS

The records of 103 patients with completely resected thymoma who received postoperative mediastinal irradiation during the period between 1979 and 1998 were reviewed. The distribution according to Masaoka stage was Stage I in 17 patients, Stage II in 61 patients, and Stage III in 25 patients. Fifty-two patients were treated with involved field (IF) irradiation, and 51 patients were treated with irradiation of the whole mediastinal field with or without boost (WM irradiation). The total radiation dose to the primary tumor bed was 30-61 grays (Gy), with a median dose of 40 Gy. No patients received chemotherapy during the initial treatment. The median follow-up of the 82 living patients was 112 months (range, 24-244 months).

RESULTS

The 10-year actuarial overall and disease free survival rates for all patients were 81% and 79%, respectively. The 10-year actuarial overall survival rate was 100% for patients with Stage I disease, 90% for patients with Stage II disease, and 48% for patients with Stage III disease. In the analysis, clinical stage alone had a statistically significant impact on both overall survival and disease free survival (P < 0.0001 for both). Recurrent disease was observed in 17 patients, and the pleura was the most frequent site of first recurrence. Of 12 patients who had pleural recurrences, 11 patients had pleural dissemination remote from the initial tumor site. No recurrence was observed in any of the 17 patients with Stage I disease, and 6 of 61 patients (10%) with Stage II disease and 11 of 25 patients (44%) with Stage III disease experienced recurrences. With regard to intrathoracic recurrences, there were no recurrences within the irradiated field in any of the 103 patients, and no dose response correlation was seen in intrathoracic control (incidence of intrathoracic recurrence: 2 of 19 patients in the group that received < 40 Gy, 6 of 45 patients in the group that received 40 Gy, and 7 of 39 patients in the group that received > 40 Gy). With respect to treatment field, mediastinal recurrences were observed in 4 of 52 patients (8%) who were treated with IF irradiation, whereas 0 of 51 patients who were treated with WM irradiation experienced mediastinal recurrences. Pleural-based recurrences were observed both in patients who were treated with IF irradiation (7 of 52 patients) and in patients who were treated with WM irradiation (5 of 51 patients). According to the degree of pathologic tumor invasion, 0 of 71 patients without pleural invasion had pleural-based recurrences (0 of 17 patients with Stage I disease, 0 of 51 patients with Stage II disease, and 0 of 3 patients with Stage III disease), whereas 12 of 32 patients (38%) with pleural invasion had pleural-based recurrences (4 of 10 patients with Stage II disease and 8 of 22 patients with Stage III disease).

CONCLUSIONS

The current results indicated that WM irradiation with a total dose of 40 Gy was effective in preventing mediastinal recurrence for patients with completely resected thymoma. However, in patients with pathologic pleural invasion of the tumor, mediastinal irradiation alone was insufficient to avoid pleural-based recurrence.

Timoma: discussão sobre tratamento e prognóstico

Objetivo: Mostrar uma casuística de pacientes com timoma, tratados cirurgicamente, com ou sem outra terapia associada, no Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Sudeste do Brasil, avaliando o prognóstico destes. Métodos: Entre 1965 e 1998 foram operados 104 pacientes com neoplasias do timo, sendo 69 (66,3%) do sexo masculino; a idade média ao diagnóstico foi de 47,9 ± 16,3 anos, com faixa de variação de 13 a 76 anos de idade. Resultados: Dos 104 operados, 89 (85,6%) foram submetidos a ressecção total do timoma, 6 (5,8%) a ressecção parcial e 9 (8,6%) a biópsia. O diagnóstico anatomopatológico (timoma x timoma maligno) e a cirurgia (biópsia x ressecção total x ressecção parcial) foram significativamente preditivos (p < 0,02) para o tempo médio de sobrevida. Conclusão: A ressecção completa é o tratamento de escolha para os timomas. Esses tumores, quando não invasivos e ressecados completamente, apresentam bom prognóstico imediato e tardio.

Thymoma: update for the new millennium

Thymomas are relatively common tumors of the anterior superior mediastinum. They are usually relatively slowly growing tumors and their prognosis depends on the macroscopic and microscopic invasion of surrounding tissues. Surgery is the mainstay treatment of thymomas, and complete resection represents one of the most important prognostic factors in this disease. Other important prognostic indicators include the tumor stage and size and the presence of symptoms. Postoperative radiotherapy is indicated in tumors with invasion of surrounding tissues, even if resection was radical, since it improves local control and survival. Cytotoxic chemotherapy has been employed in several relatively small phase II studies and in advanced disease has been demonstrated to produce a 50%-80% objective response rate. Neoadjuvant cytotoxic chemotherapy and/or external beam radiotherapy has been used with some success in patients with tumors which are not readily resectable. Novel antiproliferative systemic agents, with both cytotoxic and cytostatic mechanisms of action, are being tested in ongoing prospective clinical trials.

Stage III thymoma: pattern of failure after surgery and postoperative radiotherapy and its implication for future study

PURPOSE

With the conventional approach of surgery and postoperative radiotherapy for patients with Masaoka Stage III thymoma, progress has been slow for an improvement in the long-term survival rate over the past 20 years. The objective of this study was to evaluate the pattern of failure and survival after surgery and postoperative radiotherapy in Stage III thymoma and search for a new direction for better therapy outcome.

METHODS AND MATERIALS

Between 1975 and 1993, 111 patients with thymoma were treated at Massachusetts General Hospital. Of these, 32 patients were determined to have Masaoka Stage III thymoma. The initial treatment included surgery for clinically resectable disease in 25 patients and preoperative therapy for unresectable disease in 7 patients. Surgical procedure consisted of thymectomy plus resection of involved tissues. For postoperative radiotherapy (n = 23), radiation dose consisted of 45-50 Gy for close resection margins, 54 Gy for microscopically positive resection margins, and 60 Gy for grossly positive margins administered in 1.8 to 2.0 Gy of daily dose fractions, 5 fractions a week, over a period of 5 to 6.6 weeks. In preoperative radiotherapy, a dose of 40 Gy was administered in 2.0 Gy of daily dose fractions, 5 days a week. For patients with large tumor requiring more than 30% of total lung volume included in the target volume (n = 3), a preoperative radiation dose of 30 Gy was administered and an additional dose of 24-30 Gy was given to the tumor bed region after surgery for positive resection margins.

RESULTS

Patients with Stage III thymoma accounted for 29% (32/111 patients) of all patients. The median age was 57 years with a range from 27 to 81 years; gender ratio was 10:22 for male to female. The median follow-up time was 6 years. Histologic subtypes included well-differentiated thymic carcinoma in 19 (59%), high-grade carcinoma in 6 (19%), organoid thymoma in 4 (13%), and cortical thymoma in 3 (9%) according to the Marino and Müller-Hermelink classification. The overall survival rates were 71% and 54% at 5 and 10 years, respectively. Ten of the 25 patients who were subjected to surgery as initial treatment were found to have incomplete resection by histopathologic evaluation. The 5- and 10-year survival rates were 86% and 69% for patients (n = 15) with clear resection margins as compared with 28% and 14% for those (n = 10) with incomplete resection margins even after postoperative therapy, p = 0.002. Survival rates at 5 and 10 years were 100% and 67% for those with unresectable disease treated with preoperative radiation (n = 6) and subsequent surgery (n = 3). Recurrence was noted in 12 of 32 patients and 11 of these died of recurrent thymoma. Recurrences at pleura and tumor bed accounted for 77% of all relapses, and all pleural recurrences were observed among the patients who were treated with surgery initially.

CONCLUSION

Incomplete resection leads to poor results even with postoperative radiotherapy or chemoradiotherapy in Stage III thymoma. Pleural recurrence is also observed more often among patients treated with surgery first. These findings suggest that preoperative radiotherapy or chemoradiotherapy may result in an increase in survival by improving the rate of complete resection and reducing local and pleural recurrences.

Postoperative radiation therapy for completely resected invasive thymoma: prognostic value of pleural invasion for intrathoracic control

BACKGROUND

Optimal management of postoperative radiation therapy for completely resected invasive thymoma remains controversial. This study was conducted to assess the efficacy of postoperative mediastinal irradiation in patients with completely resected invasive thymoma.

METHODS

Between 1981 and 1996, 21 patients with completely resected invasive thymoma were referred for postoperative mediastinal irradiation. The distribution of Masaoka stages was stage II in 14 patients and stage III in seven patients. Nine patients had pleural invasion by the tumor. Thirteen patients were treated with a localized field and eight were treated with the whole mediastinal field with boost. The total dose to the primary tumor was 40-61 Gy (median: 52 Gy). The median follow-up time of the 16 living patients was 67 months (range: 29-202 months).

RESULTS

The 5- and 10-year actuarial overall survival rates in all patients were both 77%. Relapses were observed in five patients, in all of whom the sites of the first relapse involved pleural dissemination. There were no relapses within the irradiated field in any of the 21 cases. Five of nine (56%) patients with pleural invasion had relapse of pleural dissemination, while 0 of 12 (0%) patients without pleural invasion had relapse. In univariate analysis, pleural invasion had a statistically significant impact on intrathoracic control (P = 0.01).

CONCLUSIONS

The results indicated that pleural invasion might be predictive of pleural-based relapse for completely resected invasive thymoma. In patients with pleural invasion, mediastinal irradiation alone might be insufficient to avoid pleural-based relapse even after complete resection.

High-dose hemithorax irradiation in a patient with recurrent thymoma: a study of pulmonary and cardiac radiation tolerance

Malignancy spread throughout a hemithorax without distant metastasis poses a difficult therapeutic challenge. Irradiation is often not considered because of the risk of pulmonary and cardiac toxicity. We report on a patient with thymoma recurrent throughout the left pleural cavity. Disease progressed despite chemotherapy, and subsequently a radical course of radiotherapy (6,600 cGy) was delivered to the entire hemithorax. Tumor regressed markedly by the completion of radiotherapy. Although tumor regrowth was noted 1 year after radiotherapy, the patient remained markedly improved symptomatically until shortly before her death 2 years after radiotherapy. Pulmonary function tests at 1 year (forced expiratory volume of the first second and forced vital capacity) were similar to pretreatment values, and cardiac function at 2 years remained essentially normal. High-dose hemithorax irradiation may be a consideration in select cases.

Thymoma: state of the art

Thymoma is the most common tumor of the anterior mediastinum. This tumor is associated with unique paraneoplastic syndromes, such as myasthenia gravis, hypogammaglobulinemia, and pure red cell aplasia. The rarity of this tumor, however, has somewhat obscured the optimal treatment for this disease. For the majority of patients who present with localized tumor, surgical extirpation remains the standard of choice. Adjuvant radiotherapy seems to improve local control and survival. In more advanced disease, systemic therapy has been demonstrated to produce a 50% to 80% objective response rate. These observations have led to the development of multimodality therapy for the treatment of patients with advanced thymoma. In this article, we will review the current perspectives on the management of early stage and advanced thymoma.

Radiotherapy for invasive thymoma and thymic carcinoma. Clinicopathological review

PURPOSE

This study reports clinicopathological features and outcome of thymic tumors. Twenty-seven patients with invasive thymoma and 6 patients with thymic carcinoma who had received radiotherapy either primary or postoperatively were analyzed retrospectively.

PATIENTS AND METHODS

All 33 patients were irradiated with a mean dose of 50 Gy after complete resection (16 patients), partial resection (9 patients) or biopsy (8 patients). Staging was done according to the Masaoka classification; there were 12 Stage II, 12 Stage III and 9 Stage IV patients.

RESULTS

In patients with invasive thymoma Stage II to IV (median follow-up 54.4 months) Kaplan-Meier estimates of overall survival (OS), disease-specific (DSS) and disease-free survival (DFS) at 5 years were 63.7% (95% confidence interval [CI], 42 to 84%), 88.3% (CI, 75 to 100%) and 77.4% (CI, 58 to 95%), respectively. Among the prognostic factors tested, such as age, myasthenia gravis, completeness of surgery and histologic subclassification, total radiation dose, and Masaoka Stage, the latter was the only significant predictor of improved survival (p = 0.04). Considering local control, radiation dose was a significant prognostic factor (p = 0.0006). In patients with thymic carcinoma (median follow-up 43.4 months) 5-year DSS, and DFS were 22.2% (CI, 0 to 60%) and 16.7% (CI, 0 to 46%), respectively. Thymoma as compared to thymic carcinoma had a statistically significant better DSS (p = 0.007) and DFS (p = 0.0007).

CONCLUSION

Postoperative radiotherapy with sufficient doses plays an important role as adjuvant treatment in complete or incomplete resected invasive Stage II to III thymoma. In unresectable thymoma Stage III to IV as well as in thymic carcinoma a multimodality approach should be considered to improve survival.

Prognostic importance of histomorphologic subclassification for epithelial thymic tumors

BACKGROUND

The prognostic importance of various clinical variables (age, sex, association with myasthenia gravis), staging according to Masaoka, histologic type according to the Marino/Kirchner/Müller-Hermelink (MKM-H) classification, and residual tumor category (R category) was evaluated in a retrospective analysis.

METHODS

Eighty-two patients with epithelial thymic tumors (ETTs) treated in the period 1969-1993 were evaluated, and archived specimens were histologically reclassified according to the classification of MKM-H.

RESULTS

Age, sex, and association with myasthenia gravis were of no prognostic importance. The R category is of significant prognostic importance, with 5- and 10-year survival rates of 93.6% and 87.3%, respectively, for R0 resections compared with 0% at 5 years for R1 and R2 resections (p < 0.001). Staging (Masaoka) proved to be a prognostic factor (5-/10-year survival: stage I, 100%/90.9%; II, 95%/88.2%; III, 55.9%/46.6%; and IV, 10.8%/ 10.8%; p < 0.001). Histologic typing according to MKM-H is also of significant prognostic importance (5/10 year survival: thymomas: medullary, 100%/100%; mixed, 100%/100%, predominantly cortical, 68.6%/68.6%; cortical, 65.8%/65.8%; thymic carcinomas: well-differentiated type, 62.3%/44.5%; thymic carcinomas other than well-differentiated type, 33.6%/26.9%; p < 0.001). Multivariate analysis demonstrated that staging (p < 0.001), R category (p < 0.026), and MKM-H classification (p < 0.028) have an independent impact on survival.

CONCLUSIONS

Staging (Masaoka), R category, and histologic classification (MKM-H) are important independent prognostic factors for patients with epithelial thymic tumors. Complete (R0) surgical resections should be the ultimate goal in the clinical management of patients with epithelial thymic tumors.

Is postoperative radiotherapy for thymoma effective?

OBJECTIVE

The authors determined the effect of postoperative mediastinal irradiation in preventing local and pleural recurrence of thymoma.

SUMMARY BACKGROUND DATA

The role of mediastinal irradiation after incomplete resection or biopsy of an invasive thymoma is well established. However, routine use of adjuvant mediastinal irradiation for patients with thymoma after complete resection remains controversial.

METHODS

During the 19-year period from 1973 to 1992, operations were performed on 89 patients with thymoma. Of these 89 patients, 80 patients who underwent gross complete tumor resection including adjacent tissues that appeared to be invaded by tumor were selected for this study. The effects of postoperative mediastinal irradiation on the recurrence rate of thymoma were analyzed according to histologic type, clinical stage, and whether adhesions to or invasion of the pleura or pericardium were present.

RESULTS

Recurrence of thymoma was observed in 13 of 80 (16.3%) patients. No recurrence was observed in 23 patients with noninvasive thymoma. In patients with invasive thymoma whose tumor was macroscopically adherent to the pleura but not microscopically invasive (p1), recurrence was observed in 4 of 11 patients (36.4%) when mediastinal irradiation was not performed, but in none of 10 patients who received mediastinal irradiation. However, in patients with microscopic pleural invasion (p2), a high recurrence rate was observed with mediastinal irradiation (40%, 6/15 patients) or without mediastinal irradiation (30%, 3/10 patients). Postoperative mediastinal irradiation for patients with microscopical invasion to pericardium (c2) did not decrease the recurrence rate. Analysis of the mode of recurrence showed that mediastinal irradiation may have been effective in preventing local recurrence, but it did not control the pleural dissemination that was observed in 12 of 13 recurrent cases.

CONCLUSIONS

Mediastinal irradiation is not necessary for patients with noninvasive thymoma. In patients with invasive thymoma, postoperative mediastinal irradiation is effective in preventing recurrence in patients with p1 thymoma, but not in patients with p2 or c2 tumors. Further adjuvant therapy should be performed to supplement mediastinal irradiation in patients with p2 or c2 thymoma, even after complete resection.

Surgical treatment for invasive thymoma, especially when the superior vena cava is invaded

BACKGROUND

We analyzed the operative outcome of extensive surgery for invasive thymoma, especially in those with thymomas invading the superior vena cava, the left innominate vein, or both.

METHODS

We treated 41 patients with invasive thymoma, including 34 stage III, 5 stage IVa, and 2 stage IVb thymomas. Thirty-eight patients received radiotherapy preoperatively or postoperatively. In 12 patients with invasion of the superior vena cava or innominate vein, we performed angioplasty, reconstruction, or both.

RESULTS

The overall 5-year survival rate was 77% and the 10-year survival rate was 59%. In the stage III group, there was a significant difference between those with complete and those with incomplete resection. Ten of 12 patients who had angioplasty with or without reconstruction of the superior vena cava or innominate vein survived without recurrence of the tumors.

CONCLUSION

Angioplasty and vascular reconstruction are recommended because successful treatment for invasive thymomas depends on complete resection of the tumors.

Thymoma: results of a multicentric retrospective series of 149 non-metastatic irradiated patients and review of the literature. FNCLCC trialists. Fédération Nationale des Centres de Lutte Contre le Cancer

Between 1979 and 1990, 149 patients with non-metastatic thymomas were treated in ten French cancer centers. Patients were staged according to the 'GETT' classification, derived from that of Masaoka. There were 13 stage I patients, 46 stage II, 58 stage III and 32 stage IVA. Gross total resections were performed in 63 cases, subtotal resections in 31 cases and in 55 cases a biopsy alone was performed. All patients received radiotherapy and 74 were given post-operative chemotherapy. Median follow-up was 7.7 years. Local control was achieved in 117 cases (78.5%) and was influenced by the stage of the disease (p < 0.01) and the extent of surgery (p < 0.01). Twenty-six patients developed metastatis after a median period of 9 months. Five- and ten-year disease-free survival rates were 59.5% (51-67%) and 49.5% (39-60%), respectively, and were influenced by the stage of the disease (p < 0.01), the extent of surgery (p < 0.001) and a mediastinal compression on presentation (p = 5 x 10(-6)). Four factors could predict a worse overall survival in the multivariate analysis: mediastinal compression on presentation (p < 0.001), absence of chemotherapy (p < 0.001), biopsy alone (p = 0.003), and young age (p = 0.013). A worse DFS was predicted by mediastinal compression on presentation (p < 0.001), absence of chemotherapy (p < 0.001), young age (p = 0.006), and stages III-IVA (p = 0.04). Future therapeutic strategies are discussed and the literature is reviewed.