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PURPOSE ADJUVANT-CTONG1104 (ClinicalTrials.gov identifier: NCT01405079 ), a randomized phase III trial, showed that adjuvant gefitinib treatment significantly improved disease-free survival (DFS) versus vinorelbine plus cisplatin (VP) in patients with epidermal growth factor receptor ( EGFR) mutation-positive resected stage II-IIIA (N1-N2) non–small-cell lung cancer (NSCLC). Here, we report the final overall survival (OS) results. METHODS From September 2011 to April 2014, 222 patients from 27 sites were randomly assigned 1:1 to adjuvant gefitinib (n = 111) or VP (n = 111). Patients with resected stage II-IIIA (N1-N2) NSCLC and EGFR-activating mutation were enrolled, receiving gefitinib for 24 months or VP every 3 weeks for four cycles. The primary end point was DFS (intention-to-treat [ITT] population). Secondary end points included OS, 3-, 5-year (y) DFS rates, and 5-year OS rate. Post hoc analysis was conducted for subsequent therapy data. RESULTS Median follow-up was 80.0 months. Median OS (ITT) was 75.5 and 62.8 months with gefitinib and VP, respectively (hazard ratio [HR], 0.92; 95% CI, 0.62 to 1.36; P = .674); respective 5-year OS rates were 53.2% and 51.2% ( P = .784). Subsequent therapy was administered upon progression in 68.4% and 73.6% of patients receiving gefitinib and VP, respectively. Subsequent targeted therapy contributed most to OS (HR, 0.23; 95% CI, 0.14 to 0.38) compared with no subsequent therapy. Updated 3y DFS rates were 39.6% and 32. 5% with gefitinib and VP ( P = .316) and 5y DFS rates were 22. 6% and 23.2% ( P = .928), respectively. CONCLUSION Adjuvant therapy with gefitinib in patients with early-stage NSCLC and EGFR mutation demonstrated improved DFS over standard of care chemotherapy. Although this DFS advantage did not translate to a significant OS difference, OS with adjuvant gefitinib was one of the longest observed in this patient group compared with historic data.

With the rapid development of power-electronics-enabled power systems, the new converter-based generators are deteriorating the small-signal stability of the power system. Although the numerical differentiation method has been widely used for approximately calculating the eigenvalue sensitivities, its accuracy has not been carefully investigated. Besides, the ele-ment-based formulation for computing closed-form eigenvalue sensitivities has not been used in any commercial software due to the average efficiency, complicated formulation, and error-prone characteristics. Based on the matrix calculus, this paper proposes an easily manipulated formulation of the closed-form eigenvalue sensitivities with respect to the power generation. The distinguishing feature of the formulation is that all the formulas consist of vector and matrix operations, which can be performed by developed numerical algorithms to take full advantages of architectural features of the modern computer. The tests on WSCC 3-machine 9-bus system, New England to-ma-chine 39-bus system, and IEEE 54-machine 118-bus system show that the accuracy of the proposed formulation is superior to the numerical differentiation method and the efficiency is also greatly improved compared to the element-based closed-form formulation. The proposed formulation will be helpful to perform a more accurate and faster stability analysis of a power grid with converter-based devices.

Background The purpose of this study was to analyze the clinical characteristics and prognostic survival of patients with neuroendocrine tumors of the thymus (NETTs), and to develop and validate a nomogram model for predicting the prognosis of patients. Methods We conducted a retrospective analysis of patients with neuroendocrine tumors of the thymus in the Surveillance, Epidemiology, and End Results (SEER) database in the United States between 1988 and 2016. Cox scale risk regression analysis, the Kaplan‐Meier method and log‐rank test were used to carry out the significance test to determine the independent prognostic factors, from which a nomogram for NETTs was established. C‐index and calibration curve were used to evaluate the prediction accuracy of the model. External validation of the nomogram was performed using data from our center. Results A total of 254 patients with NETTs were collected in the SEER database. In the multivariable analysis, T stage, tumor grade, surgery, and chemotherapy were found to be independent factors affecting the prognosis of patients (all P, The neuroendocrine tumors of the thymus is a rare invasive tumor with a poor prognosis, and visualization models are needed to provide patients with appropriate individualized treatment strategies.In this study, we established and validated a new Nomogram model to predict the survival of patients with neuroendocrine tumors of the thymus.

Cr2+:ZnSe materials have attracted much attention as candidates for mid-infrared laser source either in the form of polycrystalline powders, or bulk ceramics, single crystals and nano-materials. In this work, a novel method for synthesizing Cr2+:ZnSe polycrystalline by direct reaction of Zn–Cr alloy and element Se (DRAE) was proposed. The zinc alloy containing 0.1 at% Cr was prepared by dissolving Cr in zinc liquid in a closed quartz ampoule. X-ray diffraction (XRD) results showed that the synthesized Cr2+:ZnSe polycrystalline was with a Zinc-blend structure. X-ray photoelectron spectroscopy (XPS) spectra showed that there was no un-reacted element of Zn, or Se. Cr2+ ions successfully and uniformly doped into ZnSe crystal lattice, which is confirmed by the diffuse reflectance spectrum, Raman spectrum and mid-infrared photoluminescence spectra. Furthermore, the sample showed excellent mid-infrared properties without luminescence quenching in the region 1800–3000 nm, and the decay-time was about 5 μs. The as-synthesized Cr2+:ZnSe polycrystalline meets the requirement for the preparation of mid-infrared ceramic or single crystals. These results indicate that the novel strategy of DRAE is valid for the synthesis of other transition metal doped ZnSe materials.

Background This study investigated the prognostic impact of (neo‐)adjuvant radiation therapies in early stage esophageal cancer. Methods A retrospective analysis using the Surveillance, Epidemiology, and End Results (SEER) database was conducted from 2004 to 2016. Patients with pathologically staged T1‐4N0M0 esophageal cancer were divided into two treatment groups: (i) neoadjuvant radiotherapy followed by surgery; and (ii) upfront esophagectomy followed by adjuvant radiotherapy. Propensity scored match and Cox proportional hazards model were used to identify covariates associated with overall survival and cancer‐specific survival. Results There were 821 patients selected, of whom 588 (71.6%) received neoadjuvant radiotherapy and 233 (28.4%) received adjuvant radiotherapy. For the entire cohort, neoadjuvant radiotherapy was associated with a significantly benefit in five‐year survival outcomes compared with adjuvant radiotherapy (P, In this population‐based study, we indicated that the addition of neoadjuvant RT for pT3‐4N0 diseases followed by esophagectomy was associated with improved cancer‐specific survival in patients with tumor lengths 5 cm and squamous cell carcinoma. The identification of higher‐risk patients for neoadjuvant therapy would be expected to yield better results than taking a uniform approach to this population, to avoid unnecessary and possibly harmful treatment in node‐negative diseases.

Background The impact of neoadjuvant chemoradiotherapy (nCRT) on early stage esophageal cancer is unknown. Here, we compared the outcomes after esophagectomy alone or nCRT plus surgery for clinically staged node‐negative esophageal cancer. Methods We searched the Surveillance, Epidemiology, and End Results database for patients with clinically node‐negative (cN0) esophageal cancer from 2004 to 2016 who underwent surgery alone or nCRT plus surgery. Propensity score matching and Cox regression analysis were used to identify covariates associated with overall survival and cancer‐specific survival. Results A total of 1587 patients were retrospectively identified, of whom 49.8% (n = 791) received nCRT and 80.2% (n = 1273) were truly node‐negative diseases. For the entire cohort, surgery alone was associated with a statistically significant but modest absolute increase in survival outcomes (P, This study focuses on the use of neoadjuvant chemoradiotherapy to esophageal carcinoma patients with clinically staged node‐negative (cN0) status. Finally, compared with surgery alone, cN0 esophageal cancer with falsely node‐negative (pN+) or localized truly node‐negative (pT3‐4N0) gain a significant survival benefit from neoadjuvant chemoradiation. However, neoadjuvant chemoradiation plus surgery was associated with decreased survival for early‐staged true node‐negative (pT1‐2N0) patients. Despite the inherent limitations, this population‐based study allows for a robust analysis of patients with cN0 esophageal carcinoma and the benefits of neoadjuvant chemoradiation when stratified by nodal and tumor status, and this finding may have significant implications on the use of neoadjuvant chemoradiation in patients with cN0 disease.

Iron-doped ZnTe (Fe2+:ZnTe) crystal can be used as promising gain media for mid-infrared laser. However, there are few studies in the optical properties of Fe2+:ZnTe crystal from mid-infrared to ultraviolet. In this work, large size Fe2+:ZnTe bulk crystal (the concentration of Fe ions is about 1019 cm−3) with a dimension of Φ30 mm × 50 mm was grown by the temperature gradient solution growth (TGSG) method. The luminescence and optical properties of Fe2+:ZnTe from terahertz wave to ultraviolet wave have been studied. The evaluated refractive index of Fe2+:ZnTe crystal is approximately 2.5–3.0 at the frequency range of 0.5–2.0 THz range. And its band gap is estimated to be about 2.24 eV. It is noted that strong absorptions at the wavelength of 2.8–4.7 μm and 705 nm were observed. Based on the experimental results, the energetic positions of Fe2+ center such as 3T1, 5T2, 5E in ZnTe crystal were proposed.

The ADJUVANT study reported the comparative superiority of adjuvant gefitinib over chemotherapy in disease-free survival of resected EGFR-mutant stage II–IIIA non-small cell lung cancer (NSCLC). However, not all patients experienced favorable clinical outcomes with tyrosine kinase inhibitors (TKI), raising the necessity for further biomarker assessment. In this work, by comprehensive genomic profiling of 171 tumor tissues from the ADJUVANT trial, five predictive biomarkers are identified (TP53 exon4/5 mutations, RB1 alterations, and copy number gains of NKX2-1, CDK4, and MYC). Then we integrate them into the Multiple-gene INdex to Evaluate the Relative benefit of Various Adjuvant therapies (MINERVA) score, which categorizes patients into three subgroups with relative disease-free survival and overall survival benefits from either adjuvant gefitinib or chemotherapy (Highly TKI-Preferable, TKI-Preferable, and Chemotherapy-Preferable groups). This study demonstrates that predictive genomic signatures could potentially stratify resected EGFR-mutant NSCLC patients and provide precise guidance towards future personalized adjuvant therapy., Adjuvant gefitinib improves outcomes in non-small cell lung cancer (NSCLC) patients compared to chemotherapy, but not in all cases. Here, the authors find genomic biomarkers of response to gefitinib in NSCLC patients from the ADJUVANT trial, and propose a score to stratify them by potential benefit from the treatment.

BackgroundGastric cancer is one of the most common malignancies worldwide. Although the diagnosis and treatment of this disease have substantially improved in recent years, the five-year survival rate of gastric cancer is still low due to local recurrence and distant metastasis. An in-depth study of the molecular pathogenesis of gastric cancer and related prognostic markers will help improve the quality of life and prognosis of patients with this disease. The purpose of this study was to identify and verify key SNPs in genes with prognostic value for gastric cancer.MethodsSNP-related data from gastric cancer patients were obtained from The Cancer Genome Atlas (TCGA) database, and the functions and pathways of the mutated genes were analyzed using DAVID software. A protein-protein interaction (PPI) network was constructed using the STRING database and visualized by Cytoscape software, and molecular complex detection (MCODE) was used to screen the PPI network to extract important mutated genes. Ten hub genes were identified using cytoHubba, and the expression levels and the prognostic value of the central genes were determined by UALCAN and Kaplan-Meier Plotter. Finally, quantitative PCR and Western blotting were used to verify the expression of the hub genes in gastric cancer cells.ResultsFrom the database, 945 genes with mutations in more than 25 samples were identified. The PPI network had 360 nodes and 1616 edges. Finally, cytoHubba identified six key genes (TP53, HRAS, BRCA1, PIK3CA, AKT1, and SMARCA4), and their expression levels were closely related to the survival rate of gastric cancer patients.ConclusionOur results indicate that TP53, HRAS, BRCA1, PIK3CA, AKT1, and SMARCA4 may be key genes for the development and prognosis of gastric cancer. Our research provides an important bioinformatics foundation and related theoretical foundation for further exploring the molecular pathogenesis of gastric cancer and evaluating the prognosis of patients.

ZnTe crystal is a promising electro-optical crystal materials applied for THz generation and detection. However, there is still a big challenge to obtain large sized high quality ZnTe crystals. In this work, large sized ZnTe bulk crystals with Φ30 mm × 150 mm were grown by the traveling solvent melting zone (TSMZ) method. With the characterization of the optical and electrical properties of as-grown ZnTe crystals, the band gap (2.22 eV), high IR transmittance (around 60%), high resistivity (3.5 × 103 Ω·cm), low density (1.3 × 105 cm−2) and small sizes (3 μm - 5 μm) of Te inclusions in ZnTe crystals, low etch pit densities (1.5 × 105 cm−2), high peak intensity to FWHM ratio (2.5 × 104) of the LO peak in the Raman spectra were obtained. Furthermore, the THz transmission spectra was measured and the maximum transmittance is more than 40% at the range of 0.3 - 3 THz. Based on these results, high quality and large aspect ratio ZnTe bulk crystals can be obtained by the TSMZ technique. Our work has greatly facilitated the application of ZnTe crystals in THz device.

Histologically node negative esophageal squamous cell carcinoma (pN0 ESCC) after radical resection still carries a significant risk of recurrence, especially in high-risk patients. Our previous study showed that the risk of recurrence was associated with tumor location and cell differentiation, as well as the presence of lymphovascular invasion. Most recurrence occurs within two years after surgery. There is still a lack of knowledge on the risks or potential benefits of postoperative adjuvant therapies for high-risk pN0 ESCC patients. This study was designed to evaluate the efficacy and toxicity of adjuvant therapies after radical surgery in high-risk patients with pN0 ESCC. This study is a multicenter, prospective, controlled randomized trial, which will compare the differences between either adjuvant chemotherapy or adjuvant radiotherapy and surgery alone for high-risk pN0 ESCC. Patients in group A will receive three cycles of adjuvant chemotherapy with paclitaxel and cisplatin, patients in group B will receive adjuvant radiotherapy with intensity-modulated radiation of 50 Gy, and patients in group C (the control) will receive surgery alone. The primary endpoint is three-year disease-free survival. Secondary endpoints include toxicity of adjuvant therapies and five-year overall survival. One hundred and sixty-two patients in each group are required and a total of 486 patients will finally be enrolled into the study. This will be the first randomized trial to investigate the necessity or potential benefit of postoperative adjuvant therapies for high-risk pN0 ESCC patients.

Background This study aimed to identify variables associated with anastomotic leakage after esophagectomy and established a tool for anastomotic leakage prediction. Methods Twenty-six preoperative and postoperative variables were retrospectively collected from esophageal cancer patients who were treated with radical esophagectomy from January 2018 to June 2020 in the Affiliated Hospital of Qingdao University. SPSS Version 23.0 and Empower Stats software were used for establishing a nomogram after screening relevant variables by univariate and multivariate Logistic regression analyses. The established nomogram was identified by depicting the receiver operating characteristic (ROC) curves and calibration curve, which was verified by 1,000 bootstrap resamples method. Results A total of 604 eligible esophageal cancer patients were included, of which 51 (8.4%) patients had anastomotic leakage. Multivariate Logistic regression analysis showed that smoking, anastomotic location, anastomotic technique, prognostic nutritional index (PNI) and ASA score were independent risks of anastomotic leakage. The area under curve (AUC) of ROC in the established nomogram was 0.764 (95% CI, 0.69-0.83). The internal validation confirmed that the nomogram had a great discrimination ability (AUC =0.766). Depicted calibration curve demonstrated a well-fitted prediction and observation probability. In addition, the decision curve analysis concluded that the newly established nomogram is significant for clinical decision-making. Conclusions This nomogram provided the individual prediction of anastomotic leakage for esophageal cancer patients after surgery, which might benefit treatment results for patients and clinicians, as well as pre-and postoperative intervention strategy-making.

Locally advanced thymic tumor usually invades adjacent great vessels, while the optimal treatment strategy for vessels resection and prosthetic replacement is still in controversial. We hereby present our series of patients undergoing autologous pericardial angioplasty for thymic malignancies. For invasive thymic tumors involving the superior vena cava (SVC), the replacement vessel was prepared by autologous pericardium and placed between the right atrium and distal left innominate vein stump to establish a SVC bypass. Then, the distal right innominate vein and proximal SVC were blocked, and the thymic tumor and involved vessel were completely resected, followed by SVC reconstruction using pericardium. We retrospectively analyzed the clinical characteristics and short-term outcomes of six related patients with autologous pericardial angioplasty. Due to the homologous advantages of autologous pericardial transplantation, those patients didn’t need to receive anticoagulant therapy during the perioperative period, so as to avoid the occurrence of hemorrhage, embolism and other graft-related complications. There were no postoperative long-term thoracic drainage (>7 days), anastomotic bleeding, reconstructed vascular stenosis, embolism or even secondary thoracotomy and other related complications occurred in this case series. The application of autologous pericardium for the replacement of mediastinal great vessels in the surgery of locally advanced thymoma is a safe and effective technique. Compared with former artificial materials, such as polytetrafluoroethylene synthetic prosthesis, autologous pericardial transplantation avoids the occurrence of high risk graft-related complications such as postoperative hemorrhage and vascular stenosis, and its clinical application prospect is worth expecting.

OBJECTIVES Video-assisted thoracoscopic surgery (VATS) has been increasingly used in the management of thymic epithelial tumours. However, its oncological efficacy remains to be proved. The purpose of this study is to compare the oncological outcomes following thoracoscopic versus open surgery in the case-matched groups of patients with early-stage thymic tumours from the Chinese Alliance for Research in Thymomas (ChART) retrospective database. METHODS Between 1994 and 2012, a total of 1087 patients who underwent surgery for UICC (Union for International Cancer Control) pathological Stage I tumours from the ChART retrospective database were recruited for this study. A propensity score-matched analysis was used to compare the long-term outcomes in patients who received VATS or open surgery. RESULTS VATS resection was performed in 271 patients (24.9%) and open surgery in 816 patients (75.1%). Before propensity score matching, the VATS group had a smaller tumour size (P = 0.002), lower grade histology (P = 0.034), lower T stage (P < 0.001) and less adjuvant therapy (P < 0.001). Propensity score matching by gender, myasthenia gravis, tumour size, histological classification, pathological T stage, extent of thymectomy, adjuvant radiotherapy and adjuvant chemotherapy identified 110 patients in each group. After matching, there was no significant difference in patient demographics, tumour characteristics or adjuvant therapy. All matched patients had R0 resection. Overall survival, disease-free survival and cumulative incidence of recurrence were only predicted by WHO histology, but not by surgical approach, in both univariable and multivariable analyses. There was no significant difference in the overall survival (85.7% vs 93.1%, P = 0.539), disease-free survival (92.5% vs 91.9%, P = 0.773), cumulative incidence of recurrence (7.1% vs 5.8%, P = 0.522) and improvement rate of myasthenia gravis (83.3% vs 88.2%, P = 0.589) between the 2 groups. CONCLUSIONS This propensity score-matched study suggests that VATS and open surgeries are associated with similar oncological outcomes for Stage I thymic epithelial tumours. Minimally invasive surgery might be an acceptable surgical approach for early-stage thymic malignancies.

In this paper we consider a class of Kirchhoff-type problem with 2-superlinear potentials. The existence of one positive solution and one negative solution will be established by using iterative technique and the Mountain Pass theorem, and a sign changing solution will be obtained by combining iterative technique and the Nehari method.

In the recent two decades, Cr2+:ZnSe crystals have been widely used as a gain media for 2∼3 μm mid-infrared lasers. However, it still remains a huge challenge for researchers to meet more and more requirements on the crystals with high qualities and large sizes. In this work, one Cr2+:ZnSe single crystal with a diameter of about 15 mm was successfully grown by chemical vapor transporting (CVT) with NH4Cl in a closed quartz ampoule without any seed. The transmission of as-grown crystal is up to 70% in the UV-VIS-NIR region and is with an intense characteristic absorption of Cr2+ near 1770 nm. The X-ray photoelectron spectroscopy (XPS) shows that the incorporation of chlorine anions does not significantly affect the valence distribution of components in the crystal. The mid-infrared photoluminescence spectra show a strong and broad emission band centered at 2400 nm with a width of 600 nm under the 1770 nm laser excitation at room temperature. The calculated cross sections of absorption and emission were 1.31×10−18 and 1.4×10−18 cm2, respectively. The measured photoluminescence decay time was about 6.9 μs at room temperature. It is confirmed that the method of CVT with NH4Cl is suitable for the growth of Cr2+:ZnSe single crystals, which are expected to have a promising prospect in mid-infrared laser applications in further.

In this paper we study the multiplicity of nontrivial solutions for a superlinear elliptic boundary value problem. By combining truncation techniques, minimax theorem, Morse theory and bifurcation method, we show that the problem has at least seven nontrivial solutions and give sign information for them. No symmetry is assumed on the domain or the nonlinearity.

To compare the predictive effect of the Masaoka-Koga staging system and the International Association for the Study of Lung Cancer (IASLC)/the International Thymic Malignancies Interest Group (ITMIG) proposal for the new TNM staging on prognosis of thymic malignancies using the Chinese Alliance for Research in Thymomas (ChART) retrospective database.From 1992 to 2012, 2,370 patients in ChART database were retrospectively reviewed. Of these, 1,198 patients with complete information on TNM stage, Masaoka-Koga stage, and survival were used for analysis. Cumulative incidence of recurrence (CIR) was assessed in R0 patients. Overall survival (OS) was evaluated both in an R0 resected cohort, as well as in all patients (any R status). CIR and OS were first analyzed according to the Masaoka-Koga staging system. Then, they were compared using the new TNM staging proposal.Based on Masaoka-Koga staging system, significant difference was detected in CIR among all stages. However, no survival difference was revealed between stage I and II, or between stage II and III. Stage IV carried the highest risk of recurrence and worst survival. According to the new TNM staging proposal, CIR in T1a was significantly lower comparing to all other T categories (P0.05) and there is a significant difference in OS between T1a and T1b (P=0.004). T4 had the worst OS comparing to all other T categories. CIR and OS were significantly worse in N (+) than in N0 patients. Significant difference in CIR and OS was detected between M0 and M1b, but not between M0 and M1a. OS was almost always statistically different when comparison was made between stages I-IIIa and stages IIIb-IVb. However, no statistical difference could be detected among stages IIIb to IVb.Compared with Masaoka-Koga staging, the IASLC/ITMIG TNM staging proposal not only describes the extent of tumor invasion but also provides information on lymphatic involvement and tumor dissemination. Further study using prospectively recorded information on the proposed TNM categories would be helpful to better grouping thymic tumors for predicting prognosis and guiding clinical management.

MicroRNAs (miRNAs) are involved in tumor initiation and progression. MiR-26b was reported to be significantly downregulated in non-small cell lung cancer (NSCLC). However, the underlying mechanisms of miR-26b involvement in the development and progression of NSCLC remains poorly understood. In the present study, we report that miR-26b suppresses cell metastasis in NSCLC through targeting migration and invasion enhancer 1 (MIEN1). We found that miR-26b was significantly downregulated and MIEN1 was significantly upregulated in both NSCLC tissues and cells lines. The expression levels of miR-26b were negatively related to those of MIEN1 mRNA in clinical NSCLC tissues. Furthermore, MIEN1 was confirmed to be a direct target of miR-26b by dual-luciferase reporter assay and MIEN1 expression was downregulated by miR-26b in NSCLC cells. In terms of function, transwell and wound healing assays demonstrated that the miR-26b remarkably inhibited invasion and migration of NSCLC cells, which was simulated by siRNA knockdown of MIEN1 and reversed by pcDNA/MIEN1 overexpression of MIEN1. Finally, we found that miR-26b could regulate NF-κB/MMP-9/VEGF pathway in NSCLC cells. In conclusion, this study revealed that miR-26b suppresses NSCLC metastasis by targeting MIEN1 via NF-κB/MMP-9/VEGF pathways, implicating a potential prognostic biomarker and therapeutic target for NSCLC treatment.

Thymic tumors are relatively rare malignancies comparing to other solid tumors in the chest (1). Its incidence is estimated to be at 3.93 per 1,000,000, which is about 1/00 of lung cancer and 1/25 of esophageal cancer in China. And it appears to be higher than that reported from North America, which is only 2.14 per 1,000,000 according to the SEER database. However, in the SEER database, the incidence rate was much higher in Asians (3.74 per 1,000,000) than in Caucasians (1.89 per 1,000,000) and close to the data from China. This implicates that there might be some ethnical and generic difference in thymic tumors. In the meantime, both these two registrations record only ‘malignant tumors’ that are clinically advanced diseases. A large part of early stage, low grade lesions are considered ‘benign tumors’ and thus, not registered. Therefore, the actual incidence of thymic tumors is much under-estimated. With the increasing use of screening for other malignancies such as lung cancer, it can be expected that more early stage thymic tumors would be discovered.