Systemic Treatment of Malignant Thymoma

Risk stratification of thymic epithelial tumors based on peritumor CT radiomics and semantic features

OBJECTIVES

To develop and validate nomograms combining radiomics and semantic features to identify the invasiveness and histopathological risk stratification of thymic epithelial tumors (TET) using contrast-enhanced CT.

METHODS

This retrospective multi-center study included 224 consecutive cases. For each case, 6764 intratumor and peritumor radiomics features and 31 semantic features were collected. Multi-feature selections and decision tree models were performed on radiomics features and semantic features separately to select the most important features for Masaoka-Koga staging and WHO classification. The selected features were then combined to create nomograms for the two systems. The performance of the radiomics model, semantic model, and combined model was evaluated using the area under the receiver operating characteristic curves (AUCs).

RESULTS

One hundred eighty-seven cases (56.5 years ± 12.3, 101 men) were included, with 62 cases as the external test set. For Masaoka-Koga staging, the combined model, which incorporated five peritumor radiomics features and four semantic features, showed an AUC of 0.958 (95% CI: 0.912-1.000) in distinguishing between early-stage (stage I/II) and advanced-stage (III/IV) TET in the external test set. For WHO classification, the combined model incorporating five peritumor radiomics features and two semantic features showed an AUC of 0.857 (0.760-0.955) in differentiating low-risk (type A/AB/B1) and high-risk (B2/B3/C) TET. The combined models showed the most effective predictive performance, while the semantic models exhibited comparable performance to the radiomics models in both systems (p > 0.05).

CONCLUSION

The nomograms combining peritumor radiomics features and semantic features could help in increasing the accuracy of grading invasiveness and risk stratification of TET.

CRITICAL RELEVANCE STATEMENT

Peripheral invasion and histopathological type are major determinants of treatment and prognosis of TET. The integration of peritumoral radiomics features and semantic features into nomograms may enhance the accuracy of grading invasiveness and risk stratification of TET.

KEY POINTS

Peritumor region of TET may suggest histopathological and invasive risk. Peritumor radiomic and semantic features allow classification by Masaoka-Koga staging (AUC: 0.958). Peritumor radiomic and semantic features enable the classification of histopathological risk (AUC: 0.857).

Comparative Analysis of Comprehensive Genomic Profile in Thymomas and Recurrent Thymomas Reveals Potentially Actionable Mutations for Target Therapies

Molecular profiles of thymomas and recurrent thymomas are far from being defined. Herein, we report an analysis of a comprehensive genetic profile (CGP) in a highly selected cohort of recurrent thymomas. Among a cohort of 426 thymomas, the tissue was available in 23 recurrent tumors for matching the biomolecular results obtained from primary and relapse samples. A control group composed of non-recurrent thymoma patients was selected through a propensity score match analysis. CGP was performed using the NGS Tru-SightOncology assay to evaluate TMB, MSI, and molecular alterations in 523 genes. CGP does not differ when comparing initial tumor with tumor relapse. A significantly higher frequency of cell cycle control genes alterations (100.0% vs. 57.1%, p = 0.022) is detected in patients with early recurrence (<32 months) compared to late recurrent cases. The CGPs were similar in recurrent thymomas and non-recurrent thymomas. Finally, based on NGS results, an off-label treatment or clinical trial could be potentially proposed in >50% of cases (oncogenic Tier-IIC variants). In conclusion, CGPs do not substantially differ between initial tumor vs. tumor recurrence and recurrent thymomas vs. non-recurrent thymomas. Cell cycle control gene alterations are associated with an early recurrence after thymectomy. Multiple target therapies are potentially available by performing a comprehensive CGP, suggesting that a precision medicine approach on these patients could be further explored.

Combined clinical and specific positron emission tomography/computed tomography-based radiomic features and machine-learning model in prediction of thymoma risk groups

OBJECTIVES

In this single-center study, we aimed to propose a machine-learning model and assess its ability with clinical data to classify low- and high-risk thymoma on fluorine-18 (18F) fluorodeoxyglucose (FDG) (18F-FDG) PET/computed tomography (CT) images.

METHODS

Twenty-seven patients (14 male, 13 female; mean age: 49.6 ± 10.2 years) who underwent PET/CT to evaluate the suspected anterior mediastinal mass and histopathologically diagnosed with thymoma were included. On 18F-FDG PET/CT images, the anterior mediastinal tumor was segmented. Standardized uptake value (SUV)max, SUVmean, SUVpeak, MTV and total lesion glycolysis of primary mediastinal lesions were calculated. For texture analysis first, second, and higher-order texture features were calculated. Clinical information includes gender, age, myasthenia gravis status; serum levels of lactate dehydrogenase (LDH), alkaline phosphatase, C-reactive protein, hemoglobin, white blood cell, lymphocyte and platelet counts were included in the analysis.

RESULTS

Histopathologic examination was consistent with low risk and high-risk thymoma in 15 cases and 12 cases, respectively. The age and myasthenic syndrome were statistically significant in both groups (P = 0.039 and P = 0.05, respectively). The serum LDH level was also statistically significant in both groups (450.86 ± 487.07 vs. 204.82 ± 59.04; P < 0.001). The highest AUC has been achieved with MLP Classifier (ANN) machine learning method, with a range of 0.830 then the other learning classifiers. Three features were identified to differentiate low- and high-risk thymoma for the machine learning, namely; myasthenia gravis, LDH, SHAPE_Sphericity [only for 3D ROI (nz>1)].

CONCLUSIONS

This small dataset study has proposed a machine-learning model by MLP Classifier (ANN) analysis on 18F-FDG PET/CT images, which can predict low risk and high-risk thymoma. This study also demonstrated that the combination of clinical data and specific PET/CT-based radiomic features with image variables can predict thymoma risk groups. However, these results should be supported by studies with larger dataset.

Local radiotherapy for pleural dissemination of thymic tumors after initial treatment

Pleural dissemination is a common pattern of failure after initial treatment of thymoma and thymic carcinoma, but there is no standardized treatment. As these tumors are relatively radiosensitive, we investigated the effectiveness of radiotherapy. Twenty patients underwent 33 series of local radiotherapy for 96 pleural dissemination lesions after initial treatment. Conventional radiotherapy (CRT), tomotherapy, and combination of the two were employed in 19, 13, and 1 series, respectively. The median follow-up period after the first irradiation for pleural dissemination was 46 months (range, 14-161). For all 20 patients, overall survival (OS) rates from initial radiotherapy for pleural dissemination were 100% at three years and 86% at five years. Progression-free survival (PFS) rates after 33 series of radiotherapy were 30% at three years and 16% at five years. Local control (LC) rates for 96 lesions were 98% at three years and 96% at five years. In-field recurrence was observed in only two among the 96 lesions. One patient (5%) developed grade 3 radiation pneumonitis and another (5%) developed grade 3 pericardial effusion. No other serious adverse events were observed. When disseminated nodules can be covered within localized fields, local radiotherapy may be a treatment option. Using tomotherapy, multiple lesions can be treated safely.

CT imaging-based machine learning model: a potential modality for predicting low-risk and high-risk groups of thymoma: "Impact of surgical modality choice"

INTRODUCTION

Radiomics methods are used to analyze various medical images, including computed tomography (CT), magnetic resonance, and positron emission tomography to provide information regarding the diagnosis, patient outcome, tumor phenotype, and the gene-protein signatures of various diseases. In low-risk group, complete surgical resection is typically sufficient, whereas in high-risk thymoma, adjuvant therapy is usually required. Therefore, it is important to distinguish between both. This study evaluated the CT radiomics features of thymomas to discriminate between low- and high-risk thymoma groups.

MATERIALS AND METHODS

In total, 83 patients with thymoma were included in this study between 2004 and 2019. We used the Radcloud platform (Huiying Medical Technology Co., Ltd.) to manage the imaging and clinical data and perform the radiomics statistical analysis. The training and validation datasets were separated by a random method with a ratio of 2:8 and 502 random seeds. The histopathological diagnosis was noted from the pathology report.

RESULTS

Four machine-learning radiomics features were identified to differentiate a low-risk thymoma group from a high-risk thymoma group. The radiomics feature names were Energy, Zone Entropy, Long Run Low Gray Level Emphasis, and Large Dependence Low Gray Level Emphasis.

CONCLUSIONS

The results demonstrated that a machine-learning model and a multilayer perceptron classifier analysis can be used on CT images to predict low- and high-risk thymomas. This combination could be a useful preoperative method to determine the surgical approach for thymoma.

Which Is the Best Treatment in Recurrent Thymoma? A Systematic Review and Meta-Analysis

BACKGROUND

Optimal recurrent thymoma management remains arguable because of limited patient numbers, and relatively late and variable recurrence patterns. Given the absence of high-quality evidence and relatively small study cohorts, we performed a quantitative meta-analysis to determine the outcome of surgical and non-surgical approaches assessing the five-year overall survival (5y overall survival (OS)) in patients with recurrent thymoma.

METHODS

We performed a comprehensive literature search and analysis according to PRISMA guidelines of studies published from 1 January 1980 until 18 June 2020 from PubMed/MEDLINE, EMBASE, and Scopus. We included studies with the cohorts' superior to 30 patients describing recurrent thymoma treatment, comparing surgical and non-surgical approaches reporting survival data.

RESULTS

Literature search revealed 3017 articles. Nine studies met all inclusion criteria and were selected for the meta-analysis. The recurrences were local/regional in 73-98% of cases and multiple in 49-72%. After treatment, 5y OS ranged from 48-77% and 10y OS from 37-51%. The quantitative meta-analysis showed a better outcome comparing surgical vs other treatments. Two studies showed statistically significant risk differences in the 5y OS favoring complete resection. After pooling results of seven studies using the random model, the combined 5y OS risk difference was 0.39, with lower and upper limits of 0.16 and 0.62, respectively (p = 0.001), and a moderate heterogeneity among studies (p = 0.098, I2 = 43.9%). Definitive conclusions could not be drawn regarding the prognostic impact of myasthenia gravis, histology, and patterns of relapse reported in literature.

CONCLUSIONS

Surgical treatment after thymoma recurrence is associated with a significant better 5y OS; therefore, surgical resection should be preferred in all technically feasible cases.

A radiomics model to predict the invasiveness of thymic epithelial tumors based on contrast‑enhanced computed tomography

In the present study, we aimed to construct a radiomics model using contrast‑enhanced computed tomography (CT) to predict the pathological invasiveness of thymic epithelial tumors (TETs). We retrospectively reviewed the records of 179 consecutive patients (89 females) with histologically confirmed TETs from two hospitals. The 82 low‑ and 97 high‑risk TETs were assigned to training (90 tumors), internal validation (49 tumors) and external validation (40 tumors) cohorts. Radiomics features extracted from preoperative contrast‑enhanced chest CT were selected using least absolute shrinkage and selection operator logistic regression. Three prediction models were developed using multivariate logistic regression analysis. Their performance and clinical utility were assessed using receiver operating characteristic curves and the DeLong test, respectively. Eight radiomics features with non‑zero coefficients were used to develop a radiomics score, which significantly differed between low‑ and high‑risk TETs (P<0.001). The subjective finding, infiltration, was independently associated with high‑risk TETs. Prediction models based on infiltration alone, the radiomics signature alone, and both these parameters showed diagnostic accuracies of 72.2% [area under curve (AUC), 0.731; 95% confidence interval (CI): 0.627‑0.819; sensitivity, 85.7%; specificity, 60.4%], 88.9% (AUC, 0.944; 95% CI: 0.874‑0.981; sensitivity, 92.9%; specificity, 85.4%), and 90.0% (AUC, 0.953; 95% CI: 0.887‑0.987; sensitivity, 92.9%; specificity, 87.5%), respectively. Decision‑curve analysis showed that the combined model added more net benefit than the single‑parameter models. In conclusion, a radiomics signature based on contrast‑enhanced CT has the potential to differentiate between low‑ and high‑risk TETs. The model incorporating the radiomics signature and subjective finding may facilitate the individualized, preoperative prediction of the pathological invasiveness of TETs.

State of the art: diagnostic tools and innovative therapies for treatment of advanced thymoma and thymic carcinoma

In this review article, state-of-the-art diagnostic tools and innovative treatments of thymoma and thymic carcinoma (TC) are described with special respect to advanced tumour stages. Complete surgical resection (R0) remains the standard therapeutic approach for almost all a priori resectable mediastinal tumours as defined by preoperative standard computed tomography (CT). If lymphoma or germ-cell tumours are differential diagnostic considerations, biopsy may be indicated. Resection status is the most important prognostic factor in thymoma and TC, followed by tumour stage. Advanced (Masaoka-Koga stage III and IVa) tumours require interdisciplinary therapy decisions based on distinctive findings of preoperative CT scan and ancillary investigations [magnetic resonance imaging (MRI)] to select cases for primary surgery or neoadjuvant strategies with optional secondary resection. In neoadjuvant settings, octreotide scans and histological evaluation of pretherapeutic needle biopsies may help to choose between somatostatin agonist/prednisolone regimens and neoadjuvant chemotherapy as first-line treatment. Finally, a multimodality treatment regime is recommended for advanced and unresectable thymic tumours. In conclusion, advanced stage thymoma and TC should preferably be treated in experienced centres in order to provide all modern diagnostic tools (imaging, histology) and innovative therapy techniques. Systemic and local (hyperthermic intrathoracic chemotherapy) medical treatments together with extended surgical resections have increased the therapeutic options in patients with advanced or recurrent thymoma and TC.

Long-term results after treatment for recurrent thymoma: a multicenter analysis

OBJECTIVES

The treatment for recurrent thymoma remains a very controversial issue. This study aims to investigate the long-term outcomes in patients with relapse according to treatment strategies and clinicopathological features.

METHODS

We retrospectively analyzed the database of three tertiary centers of thoracic surgery with the aim of reviewing the clinical records of 81 patients who experienced a recurrent thymoma after radical thymectomy, in the period between January 2001 and June 2013. The staging of both primitive and recurrent thymomas were based on the surgical and pathological criteria described by Masaoka. Experienced pathologists reassessed independently the histology of the initial thymoma and its relapse, according to the WHO classification. To the purposes of this study R+ resection or thymic carcinoma were considered as exclusion criteria. The overall outcome for long-term (5 years and 10 years) survival and disease-free survival after initial thymectomy and after treatment of recurrent thymoma were analyzed using standard statistics.

RESULTS

The population was gender balanced (41 M, 40 F), mean age: 46.4 ± 12.3 years. Fifty-four patients (66.7%) were affected by myasthenia gravis, while the other 14 by other paraneoplastic conditions. Surgery was performed in 61 patients (75.3%,), and radiotherapy and/or chemotherapy in 14 patients (17.3%). The mean follow-up duration after recurrence onset was 66.3 ± 56.4 months. Adjuvant therapy had no effect on prolonging the disease-free survival: no differences were found when investigating the administration of adjuvant chemotherapy (no CHT = 91.5 ± 76.4 months versus yes CHT=64.0 ± 41.3) and radiotherapy (no RT=86.2 ± 72.8 months versus yes RT= 93.0 ± 62.3; p = 0.8). Relapses were mostly local (mediastinum: 15 cases, pleura: 44 cases); hematogenous distant recurrences were observed in 15 cases (lung: 12; liver: 1; bone: 2 cases). An upgrade in the WHO class (defined as the "migration" of WHO class at initial thymectomy to more aggressive WHO class assigned at thymic recurrence resection) was found in 25/61 cases (40.9%), but this phenomenon apparently did not influence patient's prognosis. Overall, the 5- and 10-year survival rates after the initial thymectomy were 94.8% and 71.7%, respectively, while the 5- and 10-year survival rates after the treatment of the recurrence at the thymic level were 73.6% and 48.3%, respectively (82.4% at 5 years and 65.4% at 10 years when a R0-re-resection was obtained). The analysis on the trends of disease-free survival indicated that the site of recurrence (hematogenous diffusion) seems to be associated to a higher risk of re-relapse (p = 0.01).

CONCLUSIONS

Even following a thymectomy performed with radical intent, thymoma may recur several years later, usually as a locoregional relapse. A rewarding long-term survival may be expected after treatment, especially when a re-resection (radical) is performed (82.4% at 5 years). An histopathological "WHO upgrade" (from "low-risk" WHO classes at thymectomy to "high-risk classes" at relapse) may be observed in a remarkable percentage of patients (nearly 40% in this series), but this phenomenon seems to be not correlated with any worsening of the prognosis.

Spinal metastasis of thymic carcinoma as a rare manifestation: a summary of 7 consecutive cases

BACKGROUNDS

Thymic carcinomas are very rare tumors that are often associated with extrathoracic metastasis to other organs. However, it is well known that thymic carcinomas rarely metastasize to the spine, and the prognosis, treatment, and natural course of this disease are not yet standardized.

METHODS

We describe seven thymic carcinoma patients with spinal metastasis who were diagnosed and treated in our institute from January 2006 to December 2011. We performed surgical treatment and adjuvant chemotherapy and/or radiation therapy, in consideration of each individual disease's course, and we regularly followed up the patients.

RESULTS

Of the seven patients, five were male and two were female. Six had metastases in the thoracic spine, and one had metastases in the lumbar spine. An extradural lesion was found in five patients, and two patients had both extradural and intradural lesions. The period from the primary diagnosis to spinal metastases varied widely (range, 1.23-14 years). After surgery, all patients showed an improvement of back pain and radicular pain. Two patients were lost to follow-up, but the other five maintained ambulatory function until their final follow-up. Four patients died because of pulmonary complications accompanied with the disease's progression. One patient died from uncontrolled brain metastases. After surgery, the median survival was 204±111.43 days.

CONCLUSION

Because metastasis to the spine from thymic carcinoma is very rare, there are no treatment guidelines. Nevertheless, we suggest that appropriate surgical management of the metastatic lesion is necessary for the preservation of the patient's quality of life during survival.

Chemotherapy for thymic carcinoma and advanced thymoma in adults

BACKGROUND

Thymic carcinoma or advanced thymoma is a rare cancer of the thymus gland that tends to be aggressive and infiltrate neighbouring organs, making total resection very difficult. Induction or adjuvant chemotherapy, or both, are often used in a multimodality approach to treat people affected by this condition, but the effectiveness of chemotherapy for thymic carcinoma or advanced thymoma remains uncertain.

OBJECTIVES

To assess the role of chemotherapy in adults with thymic carcinoma or advanced thymoma.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL 2012, Issue 7), MEDLINE (accessed via Ovid from 1966 to July 2012), EMBASE (accessed via Ovid, from 1980 to July 2012), Latin American and Caribbean Literature on Health Sciences (LILACS), the Chinese Biological Medicine Database (CBM, 1978 to July 2012), China National Knowledge Infrastructure (CNKI, 1980 to July 2012) and the Chinese scientific periodical database VIP Information (VIP, 1989 to July 2012). There was no language restriction in searching for studies.

SELECTION CRITERIA

We planned to include randomised controlled trials (RCTs) of  trials using chemotherapy (either single-agent or combination chemotherapy plus surgery, radiotherapy or not) for thymic carcinoma and/or advanced thymoma. We planned to include all adults (aged 18 years and over) diagnosed with thymic carcinoma and/or with Masaoka stage III or IV thymic tumours. The intended primary outcomes were overall survival (OS) and progression-free survival (PFS).

DATA COLLECTION AND ANALYSIS

Two review authors independently evaluated the search results according to the inclusion and exclusion criteria. There were no studies identified for inclusion and therefore no data extraction was completed.

MAIN RESULTS

No RCTs were eligible for inclusion in this review. We report details of excluded prospective studies in an additional table and try to provide some useful evidence regarding current practice.

AUTHORS' CONCLUSIONS

There were no RCTs eligible for inclusion in this review. In current practice the most common regimen for adult patients with thymic carcinoma or advanced thymoma is cisplatin-based chemotherapy. Considering the condition is rare, it is suggested that an international group is set up to organise and evaluate prospective collection of data from cohorts of patients to inform current clinical practice.

Activating c-KIT mutations in a subset of thymic carcinoma and response to different c-KIT inhibitors

BACKGROUND

To analyze a multi-institutional series of type C thymic carcinomas (TCs) (including neuroendocrine tumors), focusing on the expression and mutations of c-KIT.

MATERIALS AND METHODS

Immunohistochemical expression of c-KIT/CD117, p63, CD5 and neuroendocrine markers, as well as mutational analysis of c-KIT exons 9, 11, 13, 14, 17 by direct sequencing of 48 cases of TCs. Immunohistochemical and molecular data were statistically crossed with clinicopathological features.

RESULTS

Overall, 29 tumors (60%) expressed CD117, 69% were positive for CD5 and 85% (41 cases) for p63. Neuroendocrine markers stained all six atypical carcinoids and five poorly-differentiated thymic squamous cell carcinomas. Overall, six CD117-positive cases (12.5%) showed c-KIT mutation. No mutation was detected in CD117-negative tumors and carcinoids. All the mutations were found in poorly-differentiated thymic squamous cell carcinomas expressing CD117, CD5, p63 and lacking neuroendocrine markers (6 of 12 cases with these features). Mutations involved exon 11 (four cases: V559A, L576P, Y553N, W557R), exon 9 (E490K) and exon 17 (D820E).

CONCLUSIONS

All TCs need an immunohistochemical screening with CD117, while c-KIT mutation analysis is mandatory only in CD117-positive cases, particularly when coexpressing CD5 and p63, lacking neuroendocrine differentiation. The finding of c-KIT mutation can predict efficacy with different c-KIT inhibitors.

Prediction of thymoma histology and stage by radiographic criteria

Thymic epithelial tumors, such as thymomas and thymic carcinomas, are the most common primary neoplasms of the mediastinum. In 1999, the World Health Organization (WHO) proposed a consensus classification of thymic epithelial tumors based on the morphology of the epithelial cells and the ratio of lymphocytes to epithelial cells, which was revised in 2004. The latest classification system stratifies thymic epithelial tumors into six categories: types A, AB, B1, B2, B3, and thymic carcinoma. This article describes the prediction of thymoma histology and stage on the basis of radiographic criteria by reviewing the following: the WHO histologic classification of thymic epithelial tumors, the clinical staging of thymomas based on prognosis, and the radiographic appearance of thymomas according to the WHO histologic classification.

Epidermal growth factor receptor, C-kit, and Her2/neu immunostaining in advanced or recurrent thymic epithelial neoplasms staged according to the 2004 World Health Organization in patients treated with octreotide and prednisone: an Eastern Cooperative Oncology Group study

BACKGROUND

Advanced or recurrent nonresectable thymic epithelial tumors show only a modest response to standard chemotherapy. A recent study using octreotide and prednisone in thymic tumors, Eastern Cooperative Oncology Group study E1C97, was conducted to verify the activity of octreotide for thymic tumors. The aim of this study was to determine whether epidermal growth factor receptor (EGFR) immunoreactivity correlated with outcomes and to identify new biologic markers for potential targeted therapy. Three markers, EGFR, C-kit, and Her2/neu, were selected for evaluation in patients with advanced thymic epithelial tumors treated on E1C97.

METHODS

Of the 42 patients entered onto E1C97, 34 patients (World Health Organization [WHO] categories: type A = 1, type AB = 1, type B1 = 10, type B2 = 11 type B3 = 8, and type C = 3) had sufficient tissue available for immunohistologic study. Each tumor was assessed to have 0, 1+, 2+, or 3+ immunoreactivity in the cytoplasm or membranes of the neoplastic cells for Her2/neu and EGFR and for the presence or absence of C-kit immunoreactivity.

RESULTS

EGFR immunoreactivity of 2+ or 3+ was associated with more aggressive thymic tumors (WHO types B2 and B3). However, strong EGFR immunoreactivity was not consistently seen with thymic carcinoma. The presence of EGFR within cells was associated with a significantly improved progression-free survival (PFS) and a trend for overall survival (OS). Twelve patients demonstrated C-kit immunoreactivity; the lack of C-kit immunoreactivity was significantly associated with superior PFS but not OS. Her2/neu immunoreactivity was uniformly negative for all tumors evaluated. There was no association between response and biomarker status.

CONCLUSIONS

High EGFR immunoreactivity is seen in more aggressive thymic neoplasms as classified according to the 2004 WHO, but regardless of classification, the presence of EGFR in tumor cells (1+, 2+, and 3+) is associated with improved performance free survival (PFS) and a trend for better OS. In contrast, the absence of C-kit immunoreactivity was associated with improved PFS. These data suggest that EGFR and C-kit may be prognostic, and further studies of these markers in subcategories of thymic malignancies is warranted.

Thymoma and paraneoplastic myasthenia gravis

Paraneoplastic autoimmune diseases associate occasionally with small cell lung cancers and gynecologic tumors. However, myasthenia gravis (MG) occurs in at least 30% of all patients with thymomas (usually present at MG diagnosis). These epithelial neoplasms almost always have numerous admixed maturing polyclonal T cells (thymocytes). This thymopoiesis-and export of mature CD4(+)T cells-particularly associates with MG, though there are rare/puzzling exceptions in apparently pure epithelial WHO type A thymomas. Other features potentially leading to inefficient self-tolerance induction include defective epithelial expression of the autoimmune regulator (AIRE) gene and/or of major histocompatibility complex class II molecules in thymomas, absence of myoid cells, failure to generate FOXP3(+) regulatory T cells, and genetic polymorphisms affecting T-cell signaling. However, the strong focus on MG/neuromuscular targets remains unexplained and suggests some biased autoantigen expression, T-cell selection, or autoimmunization within thymomas. There must be further clues in the intriguing serological and cellular parallels in some patients with late-onset MG but without thymomas-and in others with AIRE mutations-and in the contrasts with early-onset MG, as discussed here.

CT-guided percutaneous cutting needle biopsy of thymic epithelial tumors comparison to the accuracy of computed tomographic diagnosis according to the world health organization classification

RATIONALE AND OBJECTIVES

The aims of this study were to compare diagnostic accuracy between computed tomography (CT)-guided percutaneous cutting needle biopsy (PCNB) and surgery or open biopsy for thymic epithelial tumors in accordance with the World Health Organization (WHO) classification and to evaluate computed tomographic diagnosis additionally.

MATERIALS AND METHODS

Subjects were 20 patients (11 men, 9 women) in whom CT, CT-guided PCNB, and surgery had been performed for anterior mediastinal tumors. All diagnoses of both CT-guided PCNB and surgery or open biopsy were made in accordance with the WHO classification. Computed tomographic diagnoses were performed by two radiologists on the basis of radiologic characteristics previously reported according to the simplified WHO classification (types A and AB, type B1, types B2 and B3, and thymic carcinoma). The concordance of the WHO classification or the simplified WHO classification between the diagnosis on either CT or CT-guided PCNB and that on surgery was evaluated using the weighted kappa statistic.

RESULTS

The histologic classifications on the basis of surgical resection specimens were as follows: type A, n = 3; type AB, n = 5; type B1, n = 3; type B2, n = 4; type B3, n = 4; and thymic carcinoma, n = 1. The overall concordance with the diagnosis according to the WHO classification established using CT-guided PCNB specimens (weighted kappa = 0.757) was higher than that using computed tomographic diagnosis (weighted kappa = 0.437).

CONCLUSION

CT-guided PCNB is a technique with good concordance of the WHO classification of thymic epithelial tumors between the diagnoses of surgery or open biopsy.

Preliminary results of phase II study of capecitabine and gemcitabine (CAP-GEM) in patients with metastatic pretreated thymic epithelial tumors (TETs)

BACKGROUND

No previous prospective trials have been reported with capecitabine and gemcitabine (CAP-GEM) in patients with metastatic thymic epithelial tumors (TETs). We conducted a multicenter study to determine the activity and tolerability of this regimen in pretreated TETs.

PATIENTS AND METHODS

A total of 15 patients were enrolled in the first stage of phase II study. All patients received CAP-GEM every 3 weeks. The primary end point was objective response rate (RR); secondary end points were toxicity, progression-free survival (PFS) and overall survival.

RESULTS

Complete responses (CR) and partial responses were observed in three (20%) and three (20%) patients for a 40% RR, respectively. Grade 1-2 neutropenia, anemia and thrombocytopenia were the most common side-effects, noted in seven (46.7%), five (33.3%) and five (33.3%) patients, respectively. The most common grade 3 toxicity was neutropenia in three patients (20%). Median PFS was 11 months (95% confidence interval 4-17). The 1- and 2-year survival rates were 80% and 67%, respectively.

CONCLUSION

We have decided to publish the preliminary results because this regimen was more active than that expected. Although our results are preliminary, CAP-GEM shows activity and safety in pretreated TETs. Furthermore, multicenter trials, also in first-line setting, are necessary to confirm our results.

Management of pleural recurrence after curative resection of thymoma

OBJECTIVE

A complete surgical resection is the cornerstone of therapy of thymic tumors. Unfortunately, there is no standard treatment for pleural recurrence. This article describes our overall experience with the surgical treatment of pleural implants in patients who previously underwent resection of a thymoma.

MATERIAL AND METHODS

From January 1980 to June 2006, 20 patients previously operated on for a thymoma were operated on for the surgical resection of pleural implants. Patients with the initial Masaoka stage IVA were excluded from our analysis. Our sample comprised 10 male and 10 female patients (12-65 years old). The surgical approach to the resection of the thymoma was as follows: video-assissted thoracic surgery in 2 patients, sternotomy in 13 patients, thoracotomy in 2 patients, and sternothoracotomy in 3 patients. The initial Masaoka stage of the thymoma was IIA in 2 patients, IIB in 7 patients, and III in 11 patients.

RESULTS

The interval between resection of the thymoma and pleural implants ranged from 11 to 156 (median 60) months. Fifteen patients had a thymus-related syndrome (in 13 patients it resulted myasthenia gravis), and in 11 patients it improved or remitted after treatment of the pleural recurrence. All the resections were performed through a posterolateral thoracotomy. Three patients underwent an iterative resection of new pleural implants. At the latest follow-up, 10 patients are still alive (8 disease-free) and 10 have died (9 of a relapse and 1 of the complications of red cell aplasia). From the pleural recurrence resection, the overall 5- and 10-year survivals are 43.1% and 25.8%, respectively.

CONCLUSIONS

Repeat operation on patients with thymoma pleural recurrences is feasible and safe. It can produce satisfactory results in terms of overall survival and paraneoplastic syndrome control. Moreover, the multimodality treatment could improve the results of surgical treatment.

Treatment of advanced thymoma and thymic carcinoma

Although thymic epithelial tumors are rare, they are relatively common among neoplasms of the anterior superior mediastinum. They usually exhibit indolent behavior, but do have the capacity to invade surrounding structures and metastasize to distant sites. Thymic carcinomas are rare, but are highly aggressive tumors that are associated with a poor prognosis. The mainstay of therapy is complete surgical resection. Locally advanced thymoma and thymic carcinoma require a multimodality treatment approach with a combination of surgery, chemotherapy, and radiation therapy to decrease the chances of recurrence and improve survival. The risk of disease recurrence lasts for a number of years after completion of primary therapy. A majority of cases of recurrent disease present as pleural recurrences. Once again, surgical resection of recurrent disease represents the cornerstone of successful therapy and is critical to long-term survival. In recent years, a better understanding of the biologic basis of thymic epithelial tumors has led to the emergence of targeted therapy directed against this malignancy.

Novel prognostic groups in thymic epithelial tumors: assessment of risk and therapeutic strategy selection

PURPOSE

To assess the role of multimodality treatment on patients with thymic epithelial tumors (TETs) (i.e., thymomas and thymic squamous cell carcinoma) and to define the prognostic classes according to the Masaoka and World Health Organization histologic classification systems.

METHODS AND MATERIALS

Primary surgery was the mainstay of therapy. Extended thymectomy was performed in all cases. The cases were primarily staged according to the Masaoka system. Adjuvant radiotherapy was given to patients diagnosed with Masaoka Stage II, III, and IVA TET. Adjuvant chemotherapy was administered in selected cases.

RESULTS

We reviewed the records of 120 patients with TETs, with a mean follow-up of 13.8 years. Of the 120 patients, 98 (81.6%) received adjuvant radiotherapy. Of these 98 patients, Grade 1-2 pulmonary or esophageal toxicity was acute in 12 (12.2%) and late in 8 (8.2%). The median overall survival was 21.6 years. Of the 120 patients, 106 were rediagnosed and reclassified according to the World Health Organization system, and the survival rate was correlated with it. Three different prognostic classes were defined: favorable, Masaoka Stage I and histologic grade A, AB, B1, B2 or Masaoka Stage II and histologic grade A, AB, B1; unfavorable, Stage IV disease or histologic grade C or Stage III and histologic grade B3; intermediate, all other combinations. The 10- and 20-year survival rate was 95% and 81% for the favorable group, 90% and 65% for the intermediate group, and 50% and 0% for the unfavorable group, respectively. Local recurrence, distant recurrence, and tumor-related deaths were also evaluated.

CONCLUSION

The analysis of our experience singled out three novel prognostic classes and the assessment of risk identified treatment selection criteria.