Thymic tumours in Denmark. A retrospective study of 213 cases from 1970-1993

Chemoradiotherapy for unresectable cases of thymic epithelial tumors: a retrospective study

BACKGROUND

Because of the rarity of thymic epithelial tumors (TETs), there is no treatment for managing unresectable tumors that is supported by a high level of evidence. We present here the clinical outcomes of concurrent or sequential chemoradiotherapy for patients with unresectable TETs.

METHODS

We collated records for 215 patients with TETs who were treated at our institution and focused on the 20 patients who underwent chemoradiotherapy without curative-intent surgical resection.

RESULTS

Six patients with thymoma (4%) and 14 patients with thymic carcinoma (19%) were treated with chemoradiotherapy. Six received concurrent therapy, and platinum-containing regimens were administered to 16 patients. The survival of patients with thymic carcinoma was poorer than that of patients with thymoma [median overall survival (OS), 64.1 and 31.4 months, respectively; P=0.059]. No significant difference in survival was observed between patients treated concurrently and sequentially (48.5 vs. 38.2 months, respectively, P=0.83) or between patients treated with platinum-containing regimens and other regimens (43.5 and 53.8 months, respectively, P=0.25).

CONCLUSIONS

Chemoradiotherapy for unresectable TETs can be beneficial, especially when administrated concurrently. Patients for concurrent chemoradiotherapy should be chosen carefully because of its effectiveness and toxicity.

The creation of the international thymic malignancies interest group as a model for rare diseases

Similar to other orphan diseases, little progress has been made in the past decades in thymic malignancies. A determination to make a difference, despite the challenges facing a rare disease, led to the formation of the International Thymic Malignancies Interest Group (ITMIG) in 2010. This organization has brought together the majority of those focused on the management of thymic malignancies and has built a foundation for scientific collaboration, including consistent use of terms, an international database, and multidisciplinary engagement of clinicians and researchers from around the world. ITMIG has embarked on the development of novel approaches to research particularly suited to a rare condition. ITMIG has gained substantial recognition for the rapid progress that has been made and serves as a model for the advancement of knowledge in a rare disease.

ITMIG consensus statement on the use of the WHO histological classification of thymoma and thymic carcinoma: refined definitions, histological criteria, and reporting

INTRODUCTION

The 2004 version of the World Health Organization classification subdivides thymic epithelial tumors into A, AB, B1, B2, and B3 (and rare other) thymomas and thymic carcinomas (TC). Due to a morphological continuum between some thymoma subtypes and some morphological overlap between thymomas and TC, a variable proportion of cases may pose problems in classification, contributing to the poor interobserver reproducibility in some studies.

METHODS

To overcome this problem, hematoxylin-eosin-stained and immunohistochemically processed sections of prototypic, "borderland," and "combined" thymomas and TC (n = 72) were studied by 18 pathologists at an international consensus slide workshop supported by the International Thymic Malignancy Interest Group.

RESULTS

Consensus was achieved on refined criteria for decision making at the A/AB borderland, the distinction between B1, B2, and B3 thymomas and the separation of B3 thymomas from TCs. "Atypical type A thymoma" is tentatively proposed as a new type A thymoma variant. New reporting strategies for tumors with more than one histological pattern are proposed.

CONCLUSION

These guidelines can set the stage for reproducibility studies and the design of a clinically meaningful grading system for thymic epithelial tumors.

Key components of chemotherapy for thymic malignancies: a systematic review and pooled analysis for anthracycline-, carboplatin- or cisplatin-based chemotherapy

Purpose

Thymic malignancies, comprising thymoma and thymic carcinoma, are rare. Consequently, optimal chemotherapy for advanced thymic malignancies remains controversial. Platinum-based chemotherapy is currently the consensus treatment based on the results of single-arm phase II trials and retrospective investigations. However, comparison of cisplatin-based and carboplatin-based chemotherapy has yet to be undertaken; the effectiveness of the addition of anthracycline also remains uncertain.

Methods

In the present study, clinical trials and retrospective data regarding platinum-based chemotherapy were analyzed. The endpoint was the response rate to each chemotherapy. For advanced thymoma, we compared platinum with anthracycline-based chemotherapy and platinum with non-anthracycline-based chemotherapy. For advanced thymic carcinoma, anthracycline-based versus non-anthracycline-based chemotherapy and carboplatin-based versus cisplatin-based chemotherapy were compared. This analysis included a retrospective study of response of advanced thymic carcinoma to irinotecan and cisplatin in our institution.

Results

The response rate for the 314 patients from 15 studies with advanced thymoma, including both prospective and retrospective data, was 69.4 % [95 % confidence interval (CI) 63.1–75.0 %] for platinum with anthracycline-based chemotherapy and 37.8 % (95 % CI 28.1–48.6 %; p < 0.0001) for platinum with non-anthracycline-based chemotherapy. The response rates after anthracycline-based and non-anthracycline-based chemotherapy for advanced thymic carcinoma were similar (41.8 vs. 40.9 %; p < 0.91), whereas the response rates after cisplatin-based and carboplatin-based chemotherapy for advanced thymic carcinoma differed significantly (53.6 vs. 32.8 %; p = 0.0029) in 206 patients from 10 studies.

Conclusions

Platinum with anthracycline-based chemotherapy is an optimal combination for advanced thymoma. For advanced thymic carcinoma, cisplatin-based chemotherapy may be superior to carboplatin-based chemotherapy.

Standard outcome measures for thymic malignancies

Thymic malignancies present particular issues due to the pace of disease progression, patterns of recurrence, and causes of death that make nuances of how outcomes are reported particularly important. The relatively limited number of patients also creates a challenge to glean as much as possible from the available experience, but risks over-interpretation and potentially misleading conclusions. Therefore the International Thymic Malignancy Interest Group has developed a set of standards for reporting of outcome measures of clinical studies, which have been adopted for collaborative projects undertaken by the organization. Widespread adoption of this baseline will enhance the ability to compare results from different series.

Thymoma and thymic carcinoma: molecular pathology and targeted therapy

Thymomas and thymic carcinomas (TC) are rare epithelial tumors of the thymus. Although most thymomas have organotypic features (i.e., resemble the normal thymus), TC are morphologically undistinguishable from carcinomas in other organs. Apart from their different morphology, TC and thymomas differ also in functional terms (TC, in contrast to thymomas, have lost the capacity to promote the maturation of intratumorous lymphocytes), have different genetic features (discussed in this review), a different immunoprofile (most TC overexpress c-KIT, whereas thymomas are consistently negative), and different clinical features (TC, in contrast to thymomas, are not associated with paraneoplastic myasthenia gravis). Thus, although all the data suggest that the biology of thymomas and TC is different, in clinical practice, their therapeutic management up to now is identical. In the age of personalized medicine, the time may have come to think this over. We will briefly review the molecular genetics of malignant thymic tumors, summarize the current status of targeted therapies with an emphasis on the multitargeted kinase inhibitors sunitinib and sorafenib, and try to outline some future directions.

A typical thymic carcinoid tumour within a thymolipoma: report of a case and review of combined tumours of the thymus

Thymolipomas are rare tumours located in the anterior mediastinum. Sometimes these tumours may be combined with thymomas or lymphomas. We present a unique case of a thymic carcinoid arising within a thymolipoma. A 68-year-old patient presented with chronic chest and neck pain, which was initially thought to be caused by coronary artery disease. A chest x-ray, exercise tolerance test and coronary angiography were unremarkable. The following CT scan of the neck and chest showed a small tumour in the anterior mediastinum. A robotic-assisted thymectomy was performed and histological examination revealed a neuroendocrine tumour of the thymus within a thymolipoma. The patient was discharged 3 days after surgery in good general condition.

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.

[Primary thymic lymphomas]

INTRODUCTION

Primary thymic lymphomas (PTLs) are uncommon, and their prognosis is linked with early treatment. A review is carried out of this disease in our hospital in order to determine the best diagnostic-therapeutic management for these patients.

MATERIAL AND METHODS

Ten LPTs--four Hodgkin's and six non-Hodgkin's (4 primary mediastinal B lymphomas [PMBLs] and 2 lymphoblastic T lymphomas [LTLs]--were reviewed. Most of the patients were females, with a mean age of 23 +/- 10 years.

RESULTS

The initial diagnostic suspicion in the Hodgkin's lymphomas was thymoma in two cases and lymphoma in the other 2. All of them underwent surgery, including an intra-operative biopsy, which was completed with a thymectomy in the two in which thymoma was reported. They were treated with radio and chemotherapy. The response was partial in two cases, and treatment was completed with a bone marrow transplant (BMT) (one died and the other had active disease). The non-Hodgkin's lymphomas had large tumors and short evolution. All of them received surgery, with an intra-operative biopsy in four and a thymectomy in two. They were treated with chemotherapy, with associated radiotherapy in two. The response was total in three, with two recurring, who are in complete remission after a BMT. In the other three the response was partial.

CONCLUSIONS

In a patient with thymic tumour with a preoperative or intraoperative study suspected of having a lymphoma, it is necessary to do a biopsy and not resective surgery, to avoid unnecessary resections and morbidity. PTLs are uncommon but aggressive, principally the non-Hodgkin's lymphomas. The main treatment is radio and chemotherapy, with associated bone marrow transplantation in selected cases.

Prognostic and Clinical Relevance of the World Health Organization Schema for the Classification of Thymic Epithelial Tumors

STUDY OBJECTIVES

Controversy has ensued about the prognostic relevance of the new World Health Organization (WHO) schema for the classification of thymoma. In this study, we present the clinical and histologic features of 108 thymomas and evaluate the usefulness of this histologic schema in view of the prognosis.

DESIGN

Retrospective, clinicopathologic analysis of our experience and a review of recent literature.

SETTING

Department of Thoracic and Cardiovascular Surgery of a university hospital.

METHODS

A series of 108 thymomas were reviewed and classified by the new WHO schema. The clinical characteristics and the survival outcome were investigated in reference to the WHO subtypes. The Cox proportional hazards model was applied to determine the factors affecting the tumor-related survival. Recent literature on the prognostic relevance of the WHO schema was reviewed.

RESULTS

There were 7 type A tumors, 25 type AB tumors, 12 type B1 tumors, 32 type B2 tumors, 20 type B3 tumors, and 12 type C tumors. The histologic subtype closely correlated with the Masaoka stage (p = 0.00). The tumor-related survivals at 5 years and 10 years were 88.0% and 77.9%, respectively. Stage III and IV tumors had a significantly worse prognosis than stage I or II tumors (p < 0.05). Type B3 tumors had an intermediate prognostic ranking in comparison with the carcinomas and with the other groups. On multivariate analysis, the WHO subtype (A-B2 vs B3 vs C) could predict the tumor-related survival, but the Masaoka stage was the most important prognostic factor affecting the postoperative survival (p = 0.026).

CONCLUSION

The Masaoka stage is the most important determinant of survival in surgically resected cases of thymoma. To clarify the prognostic relevance and clinical usefulness of the WHO schema, consistent parameters reflecting the surgical outcome and development of the diagnostic tools that could improve the interobserver agreement within type B are needed.

New WHO histologic classification predicts prognosis of thymic epithelial tumors: a clinicopathologic study of 200 thymoma cases from China

BACKGROUND

In 1999, a World Health Organization (WHO) committee published histologic criteria for distinct thymoma entities (labeled as Type A, AB, B1, B2, B3 thymomas) and for the heterogeneous group of thymic carcinomas, collectively called Type C thymomas. Whether WHO-defined histologic thymoma subtypes are of independent prognostic relevance has yet to be proved.

METHODS

Two hundred thymomas from the Shanghai Chest Hospital with a mean follow-up time of 15 years (range, 1-246 months) were studied for the relevance of WHO histologic subtype and other factors (stage, therapy, and myasthenia gravis [MG]) for survival.

RESULTS

In order of frequency, 68 patients (34.0%) had Type AB, 39 (19.5%) had Type B2, 36 (18.0%) had Type C, 27 (13.5%) had Type B3, 17 (8.5%) had Type B1, and 8 (4.0%) had Type A thymoma. Five cases (2.5%) were rare thymomas not mentioned in the WHO classification. Survival data showed significant differences among the histologic subtypes (log rank test: P < 0.001). Among patients with Type A and AB thymomas, none died of tumor; of the Type B1 thymoma patients, only one (5.9%) died at 22 months. Type B2, B3, and C thymomas had a significantly worse prognosis with 5-year survival rates of 75.0%, 70.0%, and 48.0%, respectively. Ninety-six patients (48.0%) were in Masaoka Stage I, 26 (13.0%) were in Stage II, 65 (32.5%) were in Stage III, and 13 (6.5%) were in Stage IV. Stage was highly significant in predicting survival (log rank, test P < 0.001). The association between histologic subtype and invasive behavior (stage) was statistically significant (P < 0.001). However, histology was an independent predictive factor of survival in Stage I and II thymomas: Type B2, B3, and C thymomas had a worse prognosis than Type A, AB, and B1 thymomas (log rank test: P < 0.003). Thirty patients (15.0%) presented with MG. MG was significantly more frequent in Type B2 and B3 than in Type A, AB, and B1 thymomas (P < 0.01). On multivariate analysis, MG had no adverse effect on survival (P = 0.17). Radiation or chemotherapy improved patients' survival at 5 and 10 years in Type B2, B3, and C thymomas (log rank test: P < 0.003).

CONCLUSIONS

Tumor stage is the most important determinant of survival in thymoma patients, but the WHO histologic subtype is an independent prognostic factor in Stage I and II thymomas, among which WHO Type A, AB, and B1 thymomas form a low-risk group. Patients with high-risk thymomas might profit from novel adjuvant radiochemotherapy regimens.

Spindle cell and mixed spindle/lymphocytic thymomas: an integrated clinicopathologic and immunohistochemical study of 81 cases

Forty-three cases of spindle cell thymoma (medullary, WHO type A) and 38 cases of mixed spindle/lymphocytic thymoma (WHO type AB) were studied for their clinicopathologic and immunohistochemical characteristics. Three histologic patterns of spindle cell thymoma were observed: short-spindled (57%), long-spindled (31%), and micronodular (12%). The short-spindled variant was composed of oval to short spindle cells commonly arranged in a hemangiopericytic or microcystic pattern. The long-spindled variant chiefly consisted of fibroblast-like epithelial cells mimicking fibrohistiocytic neoplasms. The micronodular variant was characterized by small nests of short spindle cells dispersed among a lymphoid stroma with frequent germinal centers. All kinds of spindle cell could be admixed with lymphocyte-rich "cortex"-like areas to constitute mixed spindle/lymphocytic thymomas. Immunohistochemically, the epithelial cells in up to 70% of the short-spindled and long-spindled variants of spindle cell thymoma and 90% of mixed spindle/lymphocytic thymomas were positive for CD20, whereas the epithelial cells in all micronodular spindle cell thymomas were negative. All of the spindle cell thymomas and most of the mixed spindle/lymphocytic thymomas in this study were found in stages I and II. Follow up of the patients did not disclose relapse or mortality directly resulting from the tumors. However, the prognosis of stage I and II spindle cell and mixed spindle/lymphocytic thymomas did not significantly differ from those of stage I and II thymomas of other types by a stage-matched survival analysis. Our data showed that spindle cell and mixed spindle/lymphocytic thymomas are distinctive in histologic pattern and immunohistochemical profile. When interpreted within the context of staging, spindle cell and mixed spindle/lymphocytic thymomas presenting in stages I and II most likely behave in an indolent fashion.