Surgical, Radiation, and Systemic Treatments of Patients With Thymic Epithelial Tumors: A Systematic Review

Age-stratified associations between radiotherapy and SPMs for FPHNC: a population-based cohort study

BACKGROUND

Second primary malignancies (SPMs) account for over 30% of total deaths in head and neck cancer (HNC) patients. The increasing use of radiotherapy raises concerns about the elevated risk of radiation-associated SPMs. This study aimed to investigate the age-stratified association between radiotherapy and SPM risk in survivors of non-metastatic primary HNC.

METHODS

Using data from the Surveillance, Epidemiology, and End Results program (2004-2015), incidence rate ratios (IRRs) and standardized incidence ratios (SIRs) were evaluated for solid and hematologic SPMs associated with radiotherapy within different age groups. Follow-up for hematologic and solid SPMs began 2 and 5 years, respectively, after the diagnosis of first primary HNC. The IRRs for SPMs were compared between radiotherapy-exposed and unexposed groups using multivariable modified Poisson regression. The SIRs were computed as the ratio of observed cancers in the cohort to expected cases derived from sex-, age-, and calendar year-matched general population incidence rates.

RESULTS

The study included 75,209 2-year survivors, with 73.2% being male and a median age of 60 years. Of these, 58,063 had survived 5 years or more. Radiotherapy was associated with an increased risk of solid SPMs [IRR = 1.16, 95% confidence interval (CI) 1.08-1.24; P < 0.001]. The associations varied significantly among young (aged 15-39 years), middle-aged (aged 40 - 64 years), and elderly (aged 65-89 years) patients. Specifically, radiotherapy was associated with an increased risk of solid SPMs in middle-aged patients (IRR = 1.21, 95% CI 1.11-1.32; P < 0.001), and a decreased risk of hematologic SPMs in elderly patients (IRR = 0.77, 95% CI 0.60-0.99; P = 0.045). Compared with the general population, young patients had an elevated risk of radiotherapy-associated second primary non-Hodgkin lymphoma (SIR = 4.01, 95% CI 1.47-8.74). Middle-aged patients showed the highest SIR for SPMs in the bones/joints (SIR = 7.72, 95% CI 4.32-12.73), while elderly patients had the highest SIR for second primary esophageal malignancies (SIR = 3.87, 95% CI 2.91-5.05). Males were more likely to develop solid SPMs compared to females.

CONCLUSIONS

This study reveals an age-stratified association between radiotherapy and the risk of SPMs in HNC patients. These findings highlight the importance of considering patient age when making treatment decisions for HNC and suggest that long-term surveillance is necessary for high-risk groups.

Novel modulation of T effector memory cells-expressing CD45RA by prednisone in inoperable advanced type B thymoma patients

Due to the covert onset of thymoma, nearly 30% of patients are diagnosed at stage III or IV, losing the opportunity for surgical treatment. We have initiated the application of prednisone in treating refractory thymoma and explored biomarkers to identify potential cases that might benefit from prednisone treatment. In a study involving 96 patients with thymoma, we confirmed a significant tumor shrinkage with prednisone acetate treatment. A reduced diameter ratio indicated that type B1 and B2 thymomas exhibited the most obvious response to prednisone acetate, especially type B2 thymoma. However, the reduced diameter ratio was < 30% in type A, AB, and B3 thymomas. Immunofluorescence and flow cytometry of tumor tissues indicated that TEMRA (T Effector Memory-Expressing CD45RA) cells primarily exist in type B thymoma. However, the percentage of interleukin-8 + TEMRA cells decreased only in B1 and B2 thymoma tissues after prednisone acetate treatment. These findings are particularly significant for patients with type B thymoma with stage III or IV.

Tumour dimension is a prognostic factor in thymic epithelial tumours: An update analysis from the ESTS thymic database: Tumour dimension in thymic tumours

OBJECTIVE

The 9thTNM proposal for thymic epithelial tumours (TETs) introduced size as category in stage I, confirming tumour infiltration type as descriptor for the other stages. Aim of this study is to evaluate the role of tumour size in TETs considering different possible cut-offs also among different subgroups.

MATERIAL AND METHODS

Clinical and pathological data of patients from ESTS thymic database who underwent surgery for TETs from1/2000 to 12/2022 were reviewed and analysed. Patients clinical data, tumour characteristics, size and organs infiltration were collected and correlated to overall survival (OS), Disease free Survival (DFS) and Cancer specific Survival (CSS) using Kaplan Meier curves. The log-rank test was used to assess differences between subgroups. A multivariable model was built using Cox-regression analysis including clinical relevant variables resulting significant at univariable (p-value < 0.05).

RESULTS

The final analysis was conducted on 2146 patients. Most patients presented tumours size >5 cm(59 %)and without surrounding structures infiltrations (51.3 %). During FUP, a recurrence occurred in 235 (11%) patients, 199 (9.3%) died, 38 due to tumour progression. Multivariable confirmed as independent negative prognostic factors age (p < 0.001), carcinoma/NETT histology (p < 0.001),TETs size >5 cm (p < 0.001, HR 2.16; 95 %CI 1.32-3.50), and infiltration (p = 0.04) for OS; advanced TNM STAGE 9th edition (p < 0.001) and carcinoma/NETT (p = 0.001) for DFS; infiltration presence (p < 0.001) and carcinoma/NETT (p < 0.001) for CSS. Significant differences in OS, DFS and CSS were present considering size cut-off 5 cm (p < 0.001, p < 0.001 and p = 0.001, respectively), while using 3 cm cut-off only DFS (p < 0.001) and CSS (p = 0.001) resulted statistically significant. Significant differences in OS, DFS and CSS were present considering surrounding organ infiltration in TETs ≤ 5 cm (p = 0.004, p < 0.001 and p = 0.001) and in TETs > 5 cm (p = 0.024, p < 0.001 and p < 0.001).

CONCLUSIONS

Tumour size resulted a significant prognosticator in TETs, and its associations with infiltration permits to identify different prognostic groups.

The clinical significance of open vs. minimally invasive surgical approaches in the management of thymic epithelial tumors and myasthenia gravis

Though advancements have been made in the pharmacologic treatment of myasthenia gravis (MG), surgical resection is not only an option as a last line of defense for those patients who do not respond to medical therapy but also remains vital for those with thymic epithelial tumors (TET). While prior studies have shown the potential superiority of minimally invasive approaches via robotic- and video-assisted thoracoscopic surgery (RATS/VATS) for thymectomy compared to open surgery, in the setting of malignancies, this outcome delineation is controversial. As RATS/VATS may be associated with less post-operative complications in the treatment of TET, some surgeons argue that the open approach is necessary for complete resection (R0 resection) and to prevent potential seeding of the malignancy. In this review article, we will compare the efficacy and implications of the different surgical approaches and techniques themselves in performing a thymectomy for autoimmune and oncologic pathologies.

Evolving treatment landscape in thymic epithelial tumors: From mechanism to therapy

Thymic epithelial tumors (TETs) are rare neoplasms of the anterior mediastinum that arise from thymic epithelial cells. Although surgery is the preferred treatment for resectable TETs, the options for unresectable or recurrent advanced-stage TETs are limited beyond platinum-based chemotherapy. The evolving landscape of TET treatments is marked by significant advancements in targeted therapies and immunotherapies, particularly with anti-angiogenic agents and immune checkpoint inhibitors (ICIs). While monotherapies demonstrated certain efficacy, the development of combination strategies is vital for improving patient outcomes. This review consolidates progress in anti-angiogenic therapies and ICIs, emphasizing the evolution of combination therapies of TETs. Furtherly, we particularly discuss new first-line strategies based on these advancements and emphasizes exploring novel treatments like antibody-drug conjugates, immunomodulatory drugs and cytokine-based agents for TETs. Mechanistically, the molecular features of TETs integrated with clinical diagnosis and targeted therapy, and immunophenotyping of TETs along with its impact on the efficacy and safety of immunotherapy are discussed. Thus, this review systemizes the development in the treatment landscape of TETs, integrating the corresponding molecular and immune mechanisms, aiming to provide new references for the treatment of TETs.

Recent advances in the development of tumor microenvironment-activatable nanomotors for deep tumor penetration

Cancer represents a significant threat to human health, with the use of traditional chemotherapy drugs being limited by their harsh side effects. Tumor-targeted nanocarriers have emerged as a promising solution to this problem, as they can deliver drugs directly to the tumor site, improving drug effectiveness and reducing adverse effects. However, the efficacy of most nanomedicines is hindered by poor penetration into solid tumors. Nanomotors, capable of converting various forms of energy into mechanical energy for self-propelled movement, offer a potential solution for enhancing drug delivery to deep tumor regions. External force-driven nanomotors, such as those powered by magnetic fields or ultrasound, provide precise control but often necessitate bulky and costly external equipment. Bio-driven nanomotors, propelled by sperm, macrophages, or bacteria, utilize biological molecules for self-propulsion and are well-suited to the physiological environment. However, they are constrained by limited lifespan, inadequate speed, and potential immune responses. To address these issues, nanomotors have been engineered to propel themselves forward by catalyzing intrinsic "fuel" in the tumor microenvironment. This mechanism facilitates their penetration through biological barriers, allowing them to reach deep tumor regions for targeted drug delivery. In this regard, this article provides a review of tumor microenvironment-activatable nanomotors (fueled by hydrogen peroxide, urea, arginine), and discusses their prospects and challenges in clinical translation, aiming to offer new insights for safe, efficient, and precise treatment in cancer therapy.

Does Surgical Removal of the Thymus Have Deleterious Consequences?

The role of immunosenescence, particularly the natural process of thymic involution during aging, is increasingly acknowledged as a factor contributing to the development of autoimmune diseases and cancer. Recently, a concern has been raised about deleterious consequences of the surgical removal of thymic tissue, including for patients who undergo thymectomy for myasthenia gravis (MG) or resection of a thymoma. This review adopts a multidisciplinary approach to scrutinize the evidence concerning the long-term risks of cancer and autoimmunity postthymectomy. We conclude that for patients with acetylcholine receptor antibody-positive MG and those diagnosed with thymoma, the removal of the thymus offers prominent benefits that well outweigh the potential risks. However, incidental removal of thymic tissue during other thoracic surgeries should be minimized whenever feasible.

Supramolecular Nanoparticles of Histone and Hyaluronic Acid for Co-Delivery of siRNA and Photosensitizer In Vitro

Small interfering RNA (siRNA) has significant potential as a treatment for cancer by targeting specific genes or molecular pathways involved in cancer development and progression. The addition of siRNA to other therapeutic strategies, like photodynamic therapy (PDT), can enhance the anticancer effects, providing synergistic benefits. Nevertheless, the effective delivery of siRNA into target cells remains an obstacle in cancer therapy. Herein, supramolecular nanoparticles were fabricated via the co-assembly of natural histone and hyaluronic acid for the co-delivery of HMGB1-siRNA and the photosensitizer chlorin e6 (Ce6) into the MCF-7 cell. The produced siRNA-Ce6 nanoparticles (siRNA-Ce6 NPs) have a spherical morphology and exhibit uniform distribution. In vitro experiments demonstrate that the siRNA-Ce6 NPs display good biocompatibility, enhanced cellular uptake, and improved cytotoxicity. These outcomes indicate that the nanoparticles constructed by the co-assembly of histone and hyaluronic acid hold enormous promise as a means of siRNA and photosensitizer co-delivery towards synergetic therapy.

Postoperative radiotherapy does not improve survival in patients with Masaoka-Koga stage IIB thymomas: A propensity score matching study based on the SEER database

This study, based on a population, explored the prognostic value of postoperative radiotherapy (PORT) for Masaoka-Koga IIB stage thymomas. Patients diagnosed with thymoma from 2004 to 2017 in the Surveillance, Epidemiology, and End Results (SEER) database were included in the retrospective study. Through propensity score matching, the baseline characteristics of the patients were successfully matched to mitigate the selection bias of PORT. Survival rates and survival curves were compared between the PORT and non-PORT groups, with potential confounding factors addressed using a multivariate Cox regression model. In this study, 785 cases of IIB stage thymoma were included from the SEER database, and 303 patients were successfully matched between PORT and non-PORT groups through propensity score matching, with no significant differences in baseline characteristics. In the PORT and non-PORT groups, 10-year overall survival rates were 65.2% versus 59.6%, and cancer-specific survival rates were 87.0% vs. 84.4%, PORT did not yield statistically significant improvements in overall survival (P = .275) or cancer-specific survival (P = .336) for stage IIB thymomas. Based on the SEER database, the results of our study indicated that PORT does not confer a significant survival benefit for IIB stage thymomas.

Impact of adjuvant radiotherapy and chemotherapy on thymoma

PURPOSE

Thymoma is a rare tumour. The most common treatment for thymoma is surgical resection, while the use of radiotherapy and chemotherapy remains controversial.

PATIENTS AND METHODS

We conducted a monocentric observational study of 31 patients diagnosed with thymoma from June 2004 to July 2020 at cancer centre in Strasbourg, France. We analysed the outcomes of the patients.

RESULTS

The 2- and 5- year locoregional relapse-free survival rates were 96.3% (95% confidence interval [CI]: 76.5-99.5%) and 68.0% (95% CI: 43.8-83.5%), respectively. Radiotherapy and chemotherapy significantly improved local tumour control (P=0.0008 and 0.04, respectively), while a larger initial tumour size significantly worsened local control rates (P=0.04). The 5- and 10-year overall survival rates were 87.1% (95% CI: 69.2-95%) and 81.7% (95% CI: 60.3-92.2%), respectively. The median overall survival was not reached, and no favourable factor was retrieved. For relapsed patients, the median overall survival after relapse was 115 months.

CONCLUSION

Despite the inherent limitations of retrospective studies with a limited patient sample size, we demonstrated that chemotherapy and radiotherapy in addition to surgery were effective in achieving local control and contributed to improving patient outcomes in thymoma. Notably, an aggressive treatment strategy at the time of relapse resulted in favourable outcomes for retreated patients.

Advanced thymic carcinoma with a hepatic metastasis treated with chemotherapy and staged resection

Thymic carcinoma is rare, with resulting treatment of patients with extrathoracic metastasis being on a case-by-case basis. We describe the management of a woman in her 70s with an incidentally discovered cystic hepatic lesion with confirmation of a solitary extrathoracic metastasis from a synchronous primary thymic carcinoma. Following chemotherapy and staged resection of the metastasis and the primary tumour, the patient remained free of disease on radiological surveillance 6 months postoperatively.

Multiparametric Evaluation of Radiomics Features and Dual-Energy CT Iodine Maps for Discrimination and Outcome Prediction of Thymic Masses

RATIONALE AND OBJECTIVES

To investigate the diagnostic value of radiomics features and dual-source dual-energy CT (DECT) based material decomposition in differentiating low-risk thymomas, high-risk thymomas, and thymic carcinomas.

MATERIALS AND METHODS

This retrospective study included 32 patients (16 males, mean age 66 ± 14 years) with pathologically confirmed thymic masses who underwent contrast-enhanced DECT between 10/2014 and 01/2023. Two experienced readers evaluated all patients regarding conventional radiomics features, as well as DECT-based features, including attenuation (HU), iodine density (mg/mL), and fat fraction (%). Data comparisons were performed using analysis of variance and chi-square statistic tests. Receiver operating characteristic curve analysis and Cox-regression tests were used to discriminate between low-risk/high-risk thymomas and thymic carcinomas.

RESULTS

Of the 32 thymic tumors, 12 (38%) were low-risk thymomas, 11 (34%) were high-risk thymomas, and 9 (28%) were thymic carcinomas. Values differed significantly between low-risk thymoma, high-risk thymoma, and thymic carcinoma regarding DECT-based features (p ≤ 0.023) and 30 radiomics features (p ≤ 0.037). The area under the curve to differentiate between low-risk/high-risk thymomas and thymic cancer was 0.998 (95% CI, 0.915-1.000; p < 0.001) for the combination of DECT imaging parameters and radiomics features, yielding a sensitivity of 100% and specificity of 96%. During a follow-up of 60 months (IQR, 35-60 months), the multiparametric approach including radiomics features, DECT parameters, and clinical parameters showed an excellent prognostic power to predict all-cause mortality (c-index = 0.978 [95% CI, 0.958-0.998], p = 0.003).

CONCLUSION

A multiparametric approach including conventional radiomics features and DECT-based features facilitates accurate, non-invasive discrimination between low-risk/high-risk thymomas and thymic carcinomas.

Epigenetics of Thymic Epithelial Tumors

Thymic epithelial tumors (TETs) arise from the epithelial cells of the thymus and consist in the 1% of all adult malignancies, despite the fact that they are the most common lesions of the anterior mediastinum. TETs can be divided mainly into thymomas, thymic carcinomas, and the rarest ad aggressive neuroendocrine forms. Despite the surgical resection is quite resolving, the diagnosis of TETs is complicated by the absence of symptoms and the clinical presentation aggravated by several paraneoplastic disorders, including myasthenia gravis. Thus, the heterogeneity of TETs prompts the search for molecular biomarkers that could be helpful for tumor characterization and clinical outcomes prediction. With these aims, several researchers investigated the epigenetic profiles of TETs. In this manuscript, we narratively review the works investigating the deregulation of epigenetic mechanisms in TETs, highlighting the need for further studies combining genetic, epigenetic, and expression data to better characterize the different molecular subtypes and identify, for each of them, the most relevant epigenetic biomarkers of clinical utility.

Genomic characterization of thymic epithelial tumors reveals critical genes underlying tumorigenesis and poor prognosis

Thymic epithelial tumors (TETs) are rare mediastinal tumors whose tumorigenesis mechanism is poorly understood. Characterization of molecular alterations in TETs may contribute to a better understanding of tumorigenesis and prognosis. Hybrid capture-based next-generation sequencing was performed on tumor tissues from 47 TETs (39 thymomas and 8 thymic carcinomas) to detect mutations in 315 tumor-associated genes. In total, 178 nonsynonymous mutations were identified, with a median of 3.79 per tumor in 47 TETs. Higher tumor mutation burden (TMB) level was more common in older TET patients, and significantly associated with the more advanced pathological type, especially in thymic carcinomas (TC) patients. The gene mutation profiles of B1-3, A/AB, and TC patients varied greatly. In the actionable mutations analysis, we found 32 actionable mutations in 24 genes. Among them, NFKBIA and TP53 mutations was the most frequently, which were only identified in TCs. Additionally, TCGA database analysis found that the expression of NFKBIA mRNA in the TCs were significantly higher than thymomas. TET patients with high NFKBIA expression had shorter overall survival compared with patients with low/medium NFKBIA expression, thus providing insights to consider NFKBIA as a potential prognosis biomarker and therapeutic target in TETs.

A novel risk classifier for predicting the overall survival of patients with thymic epithelial tumors based on the eighth edition of the TNM staging system: A population-based study

OBJECTIVE

Thymic epithelial tumors (TETs) are rare tumors that originated from thymic epithelial cells, with limited studies investigating their prognostic factors. This study aimed to investigate the prognostic factors of TETs and develop a new risk classifier to predict their overall survival (OS).

METHODS

This retrospective study consisted of 1224 TETs patients registered in the Surveillance, Epidemiology, and End Results (SEER) database, and 75 patients from the First Affiliated Hospital of Xi'an Jiaotong University. The univariate and multivariate Cox regression analyses were adopted to select the best prognostic variables. A nomogram was developed to predict the OS of these patients. The discriminative and calibrated abilities of the nomogram were assessed using the receiver operating characteristics curve (ROC) and calibration curve. Decision curve analysis (DCA), net reclassification index (NRI), and integrated discrimination improvement (IDI) were adopted to assess its net clinical benefit and reclassification ability.

RESULTS

The multivariate analysis revealed that age, sex, histologic type, TNM staging, tumor grade, surgery, radiation, and tumor size were independent prognostic factors of TETs, and a nomogram was developed to predict the OS of these patients based on these variables. The time-dependent ROC curves displayed that the nomogram yielded excellent performance in predicting the 12-, 36- and 60-month OS of these patients. Calibration curves presented satisfying consistencies between the actual and predicted OS. DCA illustrated that the nomogram will bring significant net clinical benefits to these patients compared to the classic TNM staging system. The estimated NRI and IDI showed that the nomogram could significantly increase the predictive ability of 12-, 36- and 60-month OS compared to the classic TNM staging system. Consistent findings were discovered in the internal and external validation cohorts.

CONCLUSION

The constructed nomogram is a reliable risk classifier to achieve personalized survival probability prediction of TETs, and could bring significant net clinical benefits to these patients.