Recurrence of thymoma: clinicopathological features, therapy, and prognosis

Percutaneous Image-Guided Ablation of Lung Tumors

Tumors of the lung, including primary cancer and metastases, are notoriously common and difficult to treat. Although surgical resection of lung lesions is often indicated, many conditions disqualify patients from being surgical candidates. Percutaneous image-guided lung ablation is a relatively new set of techniques that offers a promising treatment option for a variety of lung tumors. Although there have been no clinical trials to definitively compare its efficacy to those of traditional treatments, lung ablation is widely practiced and generally accepted to be safe and effective. Especially encouraging results have recently emerged for cryoablation, one of the newer ablative techniques. This article reviews the indications, techniques, contraindications, and complications of percutaneous image-guided ablation of lung tumors with special attention to cryoablation and its recent developments in protocol optimization.

Occult pleural dissemination detected intraoperatively in patients with thymic tumors: a retrospective analysis

BACKGROUND

Thymic tumors usually present with adjacent organ invasion or pleural dissemination, but very few studies have reported on occult pleural dissemination detected intraoperatively. This study aimed to investigate the risk factors that can predict pleural dissemination preoperatively.

METHODS

Consecutive patients with thymic tumors who underwent surgery from January 2010 to January 2017 were reviewed. Only patients without pleural dissemination detected preoperatively were included in this study. Demographic, clinical, pathological, and survival data were collected for statistical analysis. Further analyses were performed to find the risk factors of occult pleural dissemination.

RESULTS

A total of 352 patients with thymic tumors were included in this study. Seven patients had pleural dissemination detected intraoperatively. All pleural dissemination cases were in clinical Masaoka-Koga stage III, and most underwent the video-assisted thoracoscopic surgery (VATS) approach (or VATS exploration). Univariate analysis showed that positive squamous cell carcinoma (SCC) antigen was the only predictor of pleural dissemination (p = 0.009). Tiny nodules close to the diaphragm were detected in the computed tomography scans of 1 case after reviewing the imaging data. Tumor recurrence occurred in 5 patients during follow-up. The disease-free survival rates were better in patients with a solitary nodule than those with multiple nodules (p = 0.019). No significant difference was detected in terms of disease-free survival rates between SCC antigen positive and SCC antigen negative patients.

CONCLUSIONS

Positive SCC antigen was the only detected risk factor for predicting pleural dissemination in thymic tumors preoperatively in this study. The VATS approach (including VATS exploration) is suggested for patients with clinical Masaoka-Koga stage III and SCC antigen positive thymic tumors, according to our experience.

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

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

Thymic Carcinoma Treated by CyberKnife Stereotactic Body Radiotherapy

The standard treatment for advanced thymic carcinoma has not yet been established. Most patients have no symptoms until the advanced stage. Radiation therapy has been used for advanced stage cancer, usually in combination with surgery or chemotherapy; however, the survival rates are 30%-50%. We performed hypofractionated stereotactic radiotherapy with CyberKnife (Accuray, Sunnyvale, CA, USA) for 10 cases of advanced thymic cancer. All cases reached at least partial remission (PR) in two months with progression-free irradiated lesions and minimal radiation-related toxicity. It took only seven to 12 days for each therapy that did not require admission. CyberKnife is beneficial for patients even at the terminal stage.

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.

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.

Minimally invasive thymectomy: the Mayo Clinic experience

BACKGROUND

The prevalence of minimally invasive thymectomy (MIT) is increasing and may have significant benefit to patients in terms of morbidity and post-operative recovery. Our aim was to review the Mayo Clinic experience of MIT.

METHODS

We reviewed data from all MIT cases collected in a prospectively maintained database from January 1995 to February 2015. Data were collected regarding patient demographics, perioperative management and patient outcomes.

RESULTS

A total of 510 thymectomies were performed in 20 years. Fifty-six patients underwent MIT (45 video-assisted thoracoscopy, 11 robotic-assisted). The median age was 55 years (range, 23-87 years) with male to female ratio of 25:31. Thymoma was the main pathologic diagnosis in 27/56 patients (48%), with 11/27 (41%) associated with myasthenia gravis (MG), and 16/27 (59%) non-MG. Other pathologies included 1/56 (2%) of each teratoma, lymphoma, lymphangioma, carcinoma and thymolipoma. There were 3/56 (5%) atrophic glands, 4/56 (7%) cysts, 6/56 (11%) benign glands and 11/56 (20%) hyperplastic. Mean blood loss (mL) and operative time (min) were significantly lower in the video-assisted thoracoscopic surgery (VATS) group compared to robotic (65±41 vs. 160±205 mL, P=0.04 and 102±39 vs. 178±53 min, P=0.001, respectively). There was no 30-day mortality. Post-operative morbidity occurred in 7/45 (16%) VATS patients (phrenic nerve palsy 7%, pericarditis 4%, atrial fibrillation 2%, pleural effusion 2%) and 1/11 (9%) robotic (urinary retention requiring self-catheterization). Reoperation was required in 1/3 of VATS patients with phrenic nerve palsy. There was no significant difference in length of hospital stay [VATS 1.5 days (range, 1-4 days) and robotic 2 days (range, 1-5 days) VATS; P=0.05]. Mean follow-up was 18.4 months (range, 1-50.4 months) with no tumor recurrences.

CONCLUSIONS

MIT can be performed with low morbidity and mortality. VATS is associated with reduced blood loss, operative times and earlier hospital discharge compared to robotic MIT.

Video assisted thoracic surgery (VATS) for recurrent thymoma

Between 10-30% of patients that undergo a radical operation for thymoma develop a recurrence in a variable range of time. The surgical treatment of thymoma relapses is an established and effective therapeutic approach, particularly for a single intrathoracic recurrence; however, no agreement has been reached on the best surgical approach and the extent of surgical resection, particularly in the most common event of pleural relapses. In the era of minimally invasive approach for most thoracic pathologies, the role of the video assisted thoracic surgery (VATS) approach for thymoma recurrence resection is still unclear and controversial: to date, only few authors have reported in their series a thoracoscopic resection of pleuro-pulmonary relapses, mostly when a single lesion was present. Furthermore, a thoracoscopic approach for mediastinal recurrence has been rarely reported after a previous sternotomy to resect the primary tumor. It is likely that in the future, the role of VATS for thymic recurrence resection will be better defined and extensively studied.

Therapy for thymic epithelial tumors

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

Inflammatory pseudotumor of the thymus: A case report and review of the literature

Inflammatory pseudotumors are rare benign tumors consisting of cellular and stromal elements of a localized reactive process. While inflammatory pseudotumors are commonly detected in the lung and occasionally in other organs, only one case of inflammatory pseudotumor of the thymus has been reported in the literature to date. This report presents a 54-year-old male patient with inflammatory pseudotumor of the thymus accompanied by pulmonary inflammation. The patient presented with chest pain and moderate fever for 12 days. Enhanced computed tomography of the thorax revealed an anterior mediastinal solid and cystic mass, which constricted the left brachiocephalic vein accompanied by bilateral lung inflammation and marginal pleural effusion. The patient underwent a median sternotomy for the surgical removal of the mass. Histologically, the resected mass was composed of necrotic and fibrous tissues and inflammatory infiltrates, and the diagnosis was confirmed as an inflammatory pseudotumor of the thymus. The patient’s symptoms were resolved following surgery and the patient remained asymptomatic during the six-month follow-up period. In addition, we reviewed the previous literature and discussed the diagnosis and management of our patient. This report provides further insights into the pathogenesis and underlying mechanisms of inflammatory pseudotumors of the thymus to aid in the diagnosis and development of effective therapies.

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.

Thymoma of the middle mediastinum

Thymoma is a common anterior mediastinal mass, although thymomas have occasionally been found in the neck, pulmonary hillus, or posterior mediastinum. But a thymoma within the middle mediastinum has rarely been reported. We report a thymoma arising in the middle mediastinum with a review of the literature.

Management of myasthenic patients with thymoma

Myasthenia gravis (MG) associated with thymomas differs from nonthymomatous MG, and thymomas associated with MG are also different from non-MG thymomas. According to the World Health Organization classification, the incidence of MG in thymomas was the highest in the subtypes B2, B1, and AB. Transsternal approach is still regarded as the gold standard for surgical treatment of thymomas. Less-invasive techniques of thymectomy are promising, but it is too early to estimate their real oncological value. In the series including more than 100 patients, the prognosis for survival is better in patients with thymomas associated with MG than in those with non-MG thymomas, and the prognosis for patients with MG associated with thymoma is worse than that for patients with nonthymomatous MG.

Management of stage I and II thymoma

With a knowledgeable assessment of the clinical presentation and demographic and radiologic characteristics, most thymomas can be reliably identified preoperatively without the need for a biopsy. Surgery is the mainstay of treatment for stage I and II thymoma. The rate of complete resection is essentially 100% by open techniques, and recurrences are rare. A complete thymectomy via a sternotomy is the standard approach. Adjuvant radiotherapy after a complete resection does not appear to be of benefit. In the rare event of a recurrence, an aggressive approach should be taken with re-resection whenever possible.

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.

WHO types A and AB thymomas: not always benign

The 2004 WHO classification of thymic tumors recognizes five major subtypes of thymomas and thymic carcinoma. Subtypes A and AB thymomas are purported to be benign neoplasms, although prior studies have suggested a potential for malignant behavior. The purpose of this study was to assess the clinical behavior of A and AB thymomas identified from a large institutional pathologic database. A retrospective slide review of 500 thymic epithelial tumors identified 71 (∼ 14%) cases of types A and AB thymomas. Clinical history and follow-up information were obtained through retrospective chart review. There were 38 and 33 cases of types A and AB thymomas, respectively. Complete follow-up data were available in 37 (52%) cases. Eighteen (49%) patients (type A, n=9 and type AB, n=9) had evidence of recurrent/metastatic disease at an average of 62 months (range from 6 to 244 months) after initial diagnosis. Survival curves for patients with types A and AB thymomas, with and without recurrences, show a statistically significant difference (P=0.001 and 0.005, respectively). Analysis of this large cohort confirms the potential for subtypes A and AB thymomas to show malignant behavior. Long-term clinical monitoring, therefore, appears to be justified in these cases. This study also shows the poor correlation between the WHO classification and tumor behavior.

Thirty-five-year follow-up analysis of clinical and pathologic outcomes of thymoma surgery

BACKGROUND

The impact of myasthenia gravis on patients with thymoma is still controversial when perioperative and long-term outcomes are analyzed. With the unique opportunity of a 35-year follow-up in a single institution, thymomatous myasthenia gravis cohort, we investigated the influence of early and long-term clinical predictors.

METHODS

We reviewed a surgical series of 317 (1972 to 2007) patients with thymoma: clinical and pathologic features were analyzed as prognostic factors matched against the short- and long-term survival and recurrence rates.

RESULTS

Male to female ratio was 153:164; median age, 49 years. Myasthenia gravis coexisted in 276 patients (87.1%). Thymomas were classified according to the Masaoka (42.0% stage I, 32.2% stage II, 21.5% stage III, and 4.4% stage IV) and the World Health Organization (3.5% type A, 9.5% type AB, 19.2% type B1, 57.7% type B2, 8.2% type B3, and 1.9% thymic carcinoma) staging systems. The resection was complete in 295 patients (93.1%). Operative mortality and morbidity were respectively 1.6% and 7.6%. No differences were recorded in postoperative outcome stratifying for myasthenia gravis or comorbidities. Mean follow-up was 144.7 +/- 104.4 months. The overall 5-, 10-, 20-, and 30-year survival rates were 89.9%, 84.1%, 73%, and 58.6%, respectively. The completeness of resection (p < 0.001), the Masaoka staging (p = 0.010), and the World Health Organization classification (p < 0.001) all significantly influenced the long-term survival (univariate analysis). Only completeness of resection was significantly correlated with a better prognosis (p < 0.001) in multivariate analysis. Masaoka staging (p < 0.001) and World Health Organization classification (p < 0.001) significantly correlated with the disease-free survival in the univariate and multivariate analyses as significant prognostic factors (Masaoka, p < 0.001; World Health Organization, p = 0.011). Myasthenia gravis patients showed a better prognosis in terms of long-term survival (p = 0.046) and disease-free survival (p = 0.012) in the univariate analysis.

CONCLUSIONS

We confirm the evidence that the clinical staging and the histologic classification influence long-term survival. The presence of myasthenia gravis was not significantly related to operative outcome, but prolongs both long-term survival and disease-free survival.

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.

The role of a pseudocapsula in thymic epithelial tumors: outcome and correlation with established prognostic parameters. Results of a 20-year single centre retrospective analysis

BACKGROUND

Treatment of thymoma is often based on observation of only a few patients. Surgical resection is considered to be the most important step. Role of a pseudocapsula for surgery, its clinical significance and outcome compared with established prognostic parameters is discussed which has not been reported so far.

METHODS

84 patients with thymoma underwent resection and analysis was carried out for clinical features, prognostic factors and long-term survival.

RESULTS

Fifteen patients were classified in WHO subgroup A, 21 in AB, 29 in B and 19 patients in C. Forty two patients were classified in Masaoka stage I, 19 stage II, 9 stage III and 14 stage IV. Encapsulated thymoma was seen in 40, incomplete or missing capsula in 44 patients. In 71 complete resections, local recurrence was 5%. 5-year survival was 88.1%. Thymomas with pseudocapsula showed a significant better survival (94.9% vs. 61.1%, respectively) (p = 0.001) and was correlated with the absence of nodal or distant metastasis (p = 0.04 and 0.001, respectively). Presence of pseudocapsula as well as the Masaoka and WHO classification, and R-status were of prognostic significance. R-status and Masaoka stage appeared to be of independent prognostic significance in multivariate analysis.

CONCLUSION

Intraoperative presence of an encapsulated tumor is a good technical marker for the surgeon to evaluate resectability and estimate prognosis. Although the presence of a capsula is of strong significance in the univariate analysis, it failed in the multivariate analysis due to its correlation with clinical Masaoka stage. Masaoka stage has a stronger relevance than WHO classification to determinate long-term outcome.

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.

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.