Is postoperative radiotherapy for thymoma effective?

Thymoma metastatic to the epidural thoracic spine

Background

Thymomas rarely metastasize to the spine. Here, we present a 69-year-old female diagnosed with stage IV thymoma, which subsequently developed a symptomatic epidural thoracic spinal lesion causing thoracic myelopathy.

Case Description

The patient initially presented with paraspinal rib pain, lower extremity weakness, and gait imbalance. The magnetic resonance revealed a T10 vertebral body lesion with epidural extension causing severe spinal cord compression. A T9-T10 hemilaminotomy for tumor resection was performed; this was followed by adjuvant chemotherapy and radiation. Gross total resection was achieved, and the final pathology was metastatic thymoma. Postoperatively, the patient significantly improved.

Conclusion

Metastatic thymomas to the thoracic spine are rare. For those presenting with epidural lesions causing myelopathy, surgical resection is beneficial and may be accompanied by adjunctive radiation and chemotherapy.

Clinical characteristics, prognostic factors, and long-term outcomes associated with epithelial malignancies of the thymus: A 20-year single-institution experience

BACKGROUND

Thymic epithelial tumors are rare and include thymomas and thymic carcinomas. There is scarce literature characterizing prognostic factors and long-term outcomes in these tumors.

AIMS

This review aims to describe disease features of thymomas and thymic carcinomas and to report clinical differences among thymoma histological subtypes.

METHODS AND RESULTS

A retrospective chart review was performed at the University of Florida Shands Hospital, a tertiary care academic medical center in Gainesville, Florida, USA. The review included clinical data of adults with thymic epithelial tumors diagnosed between 2001 and 2021. Significant associations among demographics, histology, stage, and outcomes were investigated. Thymoma subgroup analysis was performed using histological subtype and sex. Forty patients with thymoma and seven patients with thymic carcinoma were included in the final analysis. Among those with thymomas, patients with subtype B1, B2, or B3 tumors were younger, had larger tumors, and presented with higher stage disease when compared to those with subtypes A or AB. Tumor recurrence was most common in subtype B2 and B3 tumors (50.0% and 16.7% vs. 0%; p < .01). However, there was no significant difference in overall survival between histologic subtypes. Compared to females, males with thymomas had superior overall survival (103.0 vs. 62.9 months; p = .021) despite presenting with larger tumors (9.8 vs. 5.8 cm; p = .041). Concomitant myasthenia gravis was associated with increased recurrence but not worsened mortality. Compared to thymomas, patients with thymic carcinoma presented with higher-stage disease and had poorer 5-year survival (50.0% vs. 93.1%; p < .01).

CONCLUSION

This study affirmed pathologic stage and resectability as prognostic factors for thymic epithelial tumors. New findings include inferior overall survival in female patients and higher recurrence rates in those with thymomas and concomitant myasthenia gravis.

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.

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.

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.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Recurrence after thymoma resection according to the extent of the resection

Background

Complete resection of the thymus is considered appropriate for a thymoma resection because any remaining thymic tissue can lead to local recurrence. However, there are few studies concerning the extent of thymus resection. Therefore, we conducted a retrospective study to investigate whether recurrence following thymoma resection correlated to the extent of resection.

Methods

Between 1986 and 2011, a total of 491 patients underwent resection of thymic epithelial tumors with curative intent. Of those, we excluded patients with an undetermined World Health Organization (WHO) histologic type, patients with type C thymoma, and patients who underwent incomplete resection (n = 21). The remaining 342 patients were reviewed retrospectively and compared recurrence according to the extent of resection.

Results

Extended thymectomy was performed in 239 patients (69.9%) and limited thymectomy was performed 103 patients (30.1%). In the extended thymectomy group, 29 recurrences occurred, and in the limited thymectomy group, 10 recurrences occurred.

Comparing rates of freedom from recurrence between two groups, there was no significant statistical difference in total recurrence (p =0.472) or local recurrence (p =0.798). After matching patients by stage and tumor size, there was no significant difference in freedom from recurrence between the two groups (p = 0.162). Additionally, after adjusting for histologic type and MG, there was also no significant difference (p = 0.125) between groups.

Conclusions

No difference in the rate of recurrence was observed in patients following limited thymectomy compared with extended thymectomy.

Postoperative radiotherapy for completely resected Masaoka stage III thymoma: a retrospective study of 65 cases from a single institution

Background

The role of adjuvant radiotherapy (RT) for patients with stage III thymoma after complete resection is not definite. Some authors have advocated postoperative RT after complete tumor resection, but some others suggested observation. In this study, we retrospectively evaluated the effect of postoperative RT on survival as well as tumor control in patients with Masaoka stage III thymoma.

Methods

Between June 1982 and December 2010, 65 patients who underwent complete resection of stage III thymoma entered the study. Fifty-three patients had adjuvant RT after surgery (S + R) and 12 had surgery only (S alone). Of patients who had adjuvant RT, 28 had three-dimensional conformal RT (3D-CRT)/intensity modulated RT (IMRT) and 25 had conventional RT. A median prescribed dose of 56 Gy (range, 28–60 Gy) was given.

Results

The median follow-up time was 50 months (range, 5–360 months). Five- and 10-year overall survival (OS) rates were 91.7% and 71.6%, respectively, for S + R and 81.5% and 65.2% for S alone (P = 0.5), respectively. In the subgroup analysis, patients with 3D-CRT/IMRT showed a trend of improved 5-year OS rate compared with conventional RT (100% vs. 86.9%, P =0.12). Compared with S alone, the 5-year OS rate was significantly improved (100% vs. 81.5%, P = 0.049). Relapses occurred in 15 patients (23.1%). There was a trend of lower crude local recurrence rates for S + R (3.8%) compared with S alone (16.7%) (P = 0.09), whereas the crude regional recurrence rates were similar (P = 0.9). No clear dose–response relationship was found according to prescribed doses.

Conclusions

Adjuvant 3D-CRT/IMRT showed potential advantages in improving survival and reducing relapse in patients with stage III thymoma after complete resection, whereas adjuvant RT did not significantly improve survival or reduce recurrence for the cohort as a whole. Doses of ≤ 50 Gy may be effective and could be prescribed for adjuvant RT. To confirm the role of adjuvant 3D-CRT/IMRT in patients who undergo a complete resection of thymoma, a multicenter randomized study should be performed.

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.

Thymic neoplasms: a clinical update

Thymoma is a unique neoplasm of the anterior mediastinum that is frequently associated with indolent growth and a variety of paraneoplastic syndromes. One third of cases are detected during the evaluation of myasthenia gravis. Classification systems of thymoma have limited ability in accurately predicting prognosis and course of disease. Thus, staging is the only way to predict clinical behavior. Encapsulated tumors that are surgically resected carry the best prognosis. Adjuvant radiotherapy is recommended for incompletely excised and most invasive thymomas. Chemotherapy in anthracycline-based chemotherapy remains the most effective chemotherapy for neoadjuvant, adjuvant or palliative treatment.

Is There a Role of Postoperative Radiation Therapy in Completely Resected Stage I/II Thymic Epithelial Tumor?

PURPOSE

Retrospective analyses of patients with stage I-II thymic epithelial tumors (TET) who were treated with either surgery alone (S) or surgery plus postoperative radiation therapy (SRT) were conducted to evaluate the role of adjuvant radiation therapy (RT).

MATERIALS AND METHODS

A total of 110 stage I-II TET patients following complete resection were included in this study. Postoperative radiation therapy was recommended for those with aggressive histologic type and/or invasive features according to the surgeons' judgment during the operation. A median dose of 54.0 Gy (range, 44 to 60 Gy) focused on the primary tumor bed was administered to 57 patients (51.8%).

RESULTS

In all patients, the rates of overall survival, disease-specific survival, and disease-free survival at 10 years were 91.7%, 97.1%, and 95.8%, respectively. No significant differences in disease-specific survival (100% in the S group and 93.5% in the SRT group at 10 years, p=0.12) and disease-free survival (98.1% in the S group and 94.5% in the SRT group at 10 years, p=0.41) were observed between the treatment groups, although a significantly larger number of World Health Organization (WHO)-type B2-C (p<0.001) and Masaoka stage II (p=0.03) tumors were observed in the SRT group than in the S group. No local recurrence was observed in the SRT group. No grade 2 or greater RT-related toxicities were observed in the SRT group.

CONCLUSION

Excellent outcomes were achieved in patients with stage I-II TET who underwent complete resection. Considering excellent local control and low morbidity, adjuvant RT may be considered in high risk patients with WHO-type B2-C histology and Masaoka stage II.

Radiotherapy for thymic neoplasms

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.

Prognostic predictors and long-term outcome of postoperative irradiation in thymoma: a study of 241 patients

The purpose of this study was to identify the prognostic predictors treated with postoperative irradiation in patients with thymoma. Two hundred forty-one patients with histologically confirmed thymoma were collected and retrospectively reviewed in this study. Fifty-four patients had stage I disease; 57, stage II; 120, stage III; 10, stage IV. One hundred sixty patients underwent total thymectomy; 63, partial resection; 18, debulking or biopsy. Patients were irradiated after surgery with median dose of 50 Gy by conventional fractionation. The overall survival rates at 5 and 10 years were 83.1% and 72.6%, respectively. The 10-year overall survival was 87% for stage I, 78.7% for stage II, 57.4% for stage III, and 24.3% for stage IV. The conclusions were drawn from this analysis. For stage I, the role of postoperative irradiation needed further investigation. For stage II-III, surgery and postoperative irradiation should be part of standard care. The favorable prognostic predictors were female, early stage, and surgical extirpation.

Limited thymectomy for stage I or II thymomas

BACKGROUND

Once an anterior mediastinal tumor has been diagnosed as a thymoma, complete excision including the thymic gland and perithymic fat is currently the procedure of choice. However, little is known about the clinical outcome of grossly encapsulated thymomas excised only with the surrounding tissue while leaving a part of the thymic gland.

METHODS

A retrospective historical comparative study was conducted on 79 patients who had received surgery for stage I (n=25) or stage II (n=54) thymomas. Total thymectomy was performed in 61 patients (Total Thymectomy Group), whereas resection of tumors with only the surrounding tissue was carried out in 18 (Limited Thymectomy Group). The follow-up interval was longer in the Limited Thymectomy Group because these patients were treated longer ago (104.2+/-58.1 months vs 67.3+/-54.8 months, p<0.05).

RESULTS

One case in the Limited Thymectomy Group showed postoperative myasthenia gravis (5.6%). Two patients with multiple thymomas (2.5%) were treated with total thymectomy. One case in the Limited Thymectomy Group, which had been diagnosed as Masaoka stage II and WHO type B3 at initial surgery, recurred. None died of tumor progression in this study. Disease free survival rates at 10 years did not differ between the Limited Thymectomy and Total Thymectomy Groups (85.7% and 82.0%, respectively). There were no statistical differences in the incidence of postoperative myasthenia gravis and disease free survival between the two groups.

CONCLUSION

Resection of thymomas with surrounding tissue instead of total thymectomy can be indicated for stage I or II thymomas in light of disease free and overall survival, post-operative onset of MG, and the incidence of multiple lesions.

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

Adjuvant radiotherapy after complete resection of localized, invasive thymic epithelial tumors is considered by many to be the standard of care, despite little supporting literature. We hypothesized that individual studies may lack statistical power to demonstrate a reduction in recurrence with this approach, but meta-analysis of published data may allow for more adequate statistical evaluation. Analysis of data from 592 patients with completely resected stage II or III thymic epithelial tumors, however, revealed no statistically significant reduction in recurrence after adjuvant radiotherapy (odds ratio 1.05; 95% confidence interval: 0.63 to 1.75; p = 0.840). Additionally, the majority of publications suggest that the most common sites of recurrence are the lung, pleura, and diaphragm, even when incompletely resected patients are included.

Thymoma: Benign Appearance, Malignant Potential

Thymoma is a rare tumor with a largely indolent growth pattern. It does, however, have malignant potential as a result of its ability to invade locally and metastasize regionally. Often associated with a number of immune- and nonimmune-mediated paraneoplastic syndromes, patient outcomes are directly related to stage of disease and the ability to achieve a complete surgical resection. Surgery is the mainstay of treatment, with adjuvant radiation recommended for invasive thymoma. Sensitive to both chemotherapy and radiation, durable responses are achievable in incompletely resected and inoperable patients. We present two cases of thymoma followed by a general discussion with an emphasis on treatment for both early and advanced-stage disease.

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.

Thymoma in a child: case report and review of the literature

Thymic lesions comprise approximately 2-3% of all pediatric mediastinal tumors and include thymic cysts, hyperplasia, carcinoma, and thymomas. Thymomas, which represent less than 1% of all mediastinal tumors, are rare mediastinal tumors in the pediatric population. Fewer than 30 cases in children have been described in the literature. These tumors are typically aggressive, with poor outcomes. We report a thymoma in a 14-year-old girl and review the available literature on thymomas and their treatment.

Adjuvant Radiation of Stage III Thymoma: Is It Necessary?

BACKGROUND

The criteria for administration of adjuvant radiation therapy after thymoma resection remains controversial, and it is unclear whether patients with Masaoka stage III thymoma benefit from adjuvant radiation. The goal of this report was to determine whether or not this group benefits from radiation therapy in disease-specific survival and disease-free survival.

METHODS

Case records of the Massachusetts General Hospital were retrospectively reviewed from 1972 to 2004. One hundred and seventy-nine patients underwent resection for thymoma, of which 45 had stage III disease.

RESULTS

Forty-five stage III patients underwent resection and in 36 it was complete. Thirty-eight stage III patients received radiation therapy. Baseline prognostic factors between radiated and nonradiated groups were similar. The addition of adjuvant radiotherapy did not alter local or distant recurrence rates in patients with stage III thymoma. Disease-specific survival at 10 years in stage III patients who did not receive radiation was 75% (95% confidence interval, 32% to 100%) and in patients who did receive radiation therapy it was 79% (95% confidence interval, 64% to 94%) (p = 0.21). The most common site of relapse was the pleura.

CONCLUSIONS

Most patients who have stage III thymoma undergo complete resection. Some patients enjoy prolonged disease-free survival without adjuvant radiation after resection of stage III thymoma. Radiation does not seem to prevent pleural recurrences when given after resection of stage III thymomas. The use of routine adjuvant radiation after a complete resection of stage III thymoma needs to be re-addressed. There may be a role for the use of chemotherapy to reduce pleural recurrences.

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.

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.

Adjuvant radiation therapy for stage II thymoma

BACKGROUND

Thymoma is difficult to study because of its indolent natural history. The criteria for administration of adjuvant radiation therapy remain controversial, and it is unclear whether patients with Masaoka stage II thymoma benefit from adjuvant radiation. The goal of this report was to determine whether or not this group benefits from radiation therapy in terms of disease-specific survival and tumor recurrence.

METHODS

Case records of the Massachusetts General Hospital were retrospectively reviewed from 1972 to 1999. One hundred fifty-five patients underwent resection for thymoma, of which, 49 had stage II disease. The world literature was reviewed using a Medline search (1966 to 2001), and a secondary review of referenced works was performed.

RESULTS

Fourteen stage II patients underwent radiation therapy. Thirty-five did not receive radiation therapy. Baseline prognostic factors between radiated and nonradiated groups were similar. All patients underwent complete resection. The addition of adjuvant radiotherapy did not significantly alter local or distant recurrence rates in stage II thymoma. Disease-specific survival at 10 years in stage II patients was 100% with radiotherapy and without radiotherapy (p = 0.87). There was one recurrence in the nonradiated group at 180 months, which was outside the usual radiation portal.

CONCLUSIONS

Most stage II patients do not require adjuvant radiation therapy and can be observed after complete resection.

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.

Recurrence of thymoma: clinicopathological features, re-operation, and outcome

BACKGROUND

Even after complete resection, recurrence of thymoma is not infrequently observed, and treatment of recurrent thymoma remains controversial.

STUDY DESIGN

One hundred and twenty-six patients underwent surgically complete resection for thymoma, and 24 of them had a recurrence. Surgical treatment of recurrent thymoma was attempted in 15 patients for a total of 18 times. In the present study, the relevance of clinicopathological features and the re-operation on the survival rate after the recurrence were determined.

RESULTS

The most frequent recurrent type was pleural dissemination (92%), with local recurrence observed in 5%. Overall 5- and 10-year survivals after recurrence were 37 and 16%, respectively. Disease-free interval after initial operation and complication of myasthenia gravis had no significant effect on postrecurrent survival. The use of postoperative mediastinal irradiation had no effect on reducing the recurrence rate or improving survival after recurrence. Two of 15 patients who underwent re-operation died of major complications after It. pleuropneumonectomy for severe pleural dissemination. In the present study, the re-operation was not significantly effective for prolongation of postrecurrence survival.

CONCLUSION

Our study showed that re-operation should not be attempted for all patients with recurrent thymoma. Because effect of subtotal resection for severe pleural recurrence is disappointing, total resection for minimal pleural dissemination or small local recurrence will be undertaken to improve postrecurrent survival. Careful follow-up for > 10 years will increase the chance of the total resection of the recurrent thymoma.

Thymoma. Analysis of prognostic factors

OBJECTIVE

We evaluated the prognostic factors for thymoma that remain controversial.

METHODS

We studied 72 consecutive patients treated for thymoma during the period between 1966 and 1997. Recurrence-free interval rates and overall survival rates calculated by the Kaplan-Meier method were compared using log-rank test by the Masaoka stage, extent of surgical resection, histology, or associated disease(s). Multivariate analysis was performed using Cox's proportional hazards model.

RESULTS

Thirty-two thymomas were at Masaoka stage I, 9 at stage II, 15 at stage III, and 16 were at stage IV. There were 56 complete resections, 7 incomplete resections (2 at stage III and 5 at stage IV), and 9 biopsies (1 at stage III and 8 at stage IV). Forty-one thymomas were cortical, 16 medullary, and 15 were mixed form. Association of myasthenia gravis was found in 20 patients, and pure red cell aplasia in 7. After an average follow-up period of 103 months, the recurrence-free 5-, 10-, 15-year interval rate was 89%, 80%, 80%, respectively, and overall 5-, 10-, 15-year survival rate was 86%, 71%, 59%, respectively. Factors influencing the recurrence-free interval and overall survival included the Masaoka stage, extent of surgical resection, and association with pure red cell aplasia. Multivariate analysis revealed stage IV tumor and association with pure red cell aplasia as risk factors for recurrence. Pure red cell aplasia indicated poor prognosis for overall survival.

CONCLUSIONS

Masaoka stage, extent of surgical resection, and association with pure red cell aplasia were prognostic factors for thymoma. Multidisciplinary treatment for stage IV tumors and better control of pure red cell aplasia, if associated, should be investigated.

Current status of the diagnosis and treatment of thymoma

Although thymomas are rare neoplasms, they are the most common tumor of the anterior mediastinum in adults. Preferred therapy for these neoplasms is complete surgical resection. If a thymoma cannot be completely resected, postoperative radiotherapy may produce satisfactory results in controlling the tumor. Significant 5- and 10-year survival rates have been recorded for patients with advanced thymomas who have been treated by radiation therapy alone. Chemotherapy may be used in patients with unresectable thymomas as well, but the results are less promising than with radiotherapy. Combinations of radiotherapy and chemotherapy used on patients with unresectable thymomas have produced encouraging results. Surveillance of patients with thymoma should be prolonged because late recurrence (more than 5 years after initial therapy) can be expected in a significant minority of patients. Aggressive therapy of late recurrence, including resection of new tumor masses and pleural metastases, has yielded successive disease-free intervals that validate persistent treatment.

Invasive thymoma with long-term survival by extensive reoperation

The recurrence of invasive thymoma is often observed; however, no accepted treatment of recurrent invasive thymoma has yet been established. We herein report a 41-year-old woman with invasive thymoma and pleural dissemination who demonstrated long-term survival after undergoing 4 operations. Based on our findings, reoperation is thus suggested in patients with intrathoracic recurrence and long-term survival can be expected.

Thymoma--the usefulness of some prognostic factors for diagnosis and surgical treatment

AIMS

The aim of the study was to identify prognostic factors which could help evaluate both the treatment offered to patients with thymoma and late results.

METHODS

Forty patients were treated for mediastinal thymoma. The patients were staged clinico-pathologically (according to Masaoka) on the basis of the retrospective analysis of their operation protocols as follows: seven (17.5%)-stage I, 19 (22. 5%)-stage II, 17 (42.5%)-stage III, seven (17.5%)-stage IV. Analysis of DNA contents in cell nuclei of 23 thymomas was performed by the flow cytofluorometric method.

RESULTS

From the whole group of patients, 65% survived for 5 years, 55% survived for 10 years and 43% survived for 15 years. We noted significant differences in survival time between stage I and stage IV (P<0.0012); stage II and stage IV (P<0.0006), as well as between stage III and stage IV (P<0. 005). Significantly worse prognosis was observed in the case of cortical thymomas as compared with medullary or mixed types (P<0. 0001 P<0.002). Analysis of DNA content showed signficantly higher probability of survival for the patients who had DI=1.0 (diploid), as compared with DNA >1.0 (aneuploid) (P<0.006). Of the 11 patients with diploid tumours, 91% survived for 5 years, but of the 12 aneuploid, only 23% survived.

CONCLUSION

The most important positive prognostic factors influencing survival rate in patients with thymoma are: lower stage, medullary type (according to Muller-Hermelink classification), possibility of performing complete resection, diploidal nature of the tumour. Multivariate analysis of survival revealed clinico-pathological stage (according to Masaoka) and histological type (according to Salyer) as significantly independent prognostic factors.

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.

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.