Long-Term Outcomes After Surgical Resection for Pleural Dissemination of Thymoma

Risk factors and prognostic factors of pleural metastases in thymic epithelial tumors: A narrative review

INTRODUCTION

Pleural metastases are common in thymic epithelial tumors (TET), which include pleural recurrence and stage IVa at initial diagnosis. However, the specific risk factors predicting its recurrence (i.e., pleural recurrence group) and prognostic factors for pleural metastasis (i.e., stage IVa) remain unclear. This review aims to identify and discuss the predictors associated with pleural metastases in patients with TET.

METHODS

A systematic literature search was conducted on PubMed, MEDLINE, Embase, and Cochrane for articles published between 1/1/1990 and 3/11/2023. The selection process was independently carried out by three researchers, and the quality of the selected papers was assessed using the Newcastle-Ottawa Scale (NOS).

RESULTS

Out of the 4932 papers reviewed, 22 were included in the final analysis: 15 papers on risk factors of pleural recurrence after primary treatment(i.e., recurrence group) and 7 papers on the prognostic factors of patients with stage IVa at diagnosis(i.e., stage IVa group). Of the 15 former articles, 5 identified pleural invasion and invasion of other tissues as significant risk factors for pleural recurrence. Four of 15 papers identified the Masaoka-Koga stage as a significant risk factor, while two of 15 papers identified the contact length between the tumor contour and the lung as a contributing factor for pleural recurrence. Additionally, two papers suggested that tumor size may be a risk factor for pleural recurrence. Six other papers discussed various factors, including a lobulated tumor contour, WHO histologic classifications B2 and B3, radiotherapy doses of≤50Gy, incomplete resection, and Entire hemithorax radio therapy, as potential risk factors. Furthermore, one paper specifically addressed the decreased risk for pleural dissemination associated with Video-Assisted Thoracoscopic Surgery (VATS) thymectomy. In patients with stage IVa at diagnosis group, three of 7 papers mentioned that resection influenced the prognosis. Two papers discussed the number of nodules in the pleura but arrived at different conclusions. One paper suggested that patients older than 50 years might have worse outcomes, while another analyzed the invasion of structures but did not find any significant results.

CONCLUSION

For pleural recurrence patients, the most commonly discussed risk factor is pleural invasion. Other identified risk factors include the Masaoka-Koga stage, contact length between the tumor contour and the lung, tumor size, lobulated tumor contour, WHO histologic classifications B2 and B3, radiotherapy doses of≤50Gy, and incomplete resection. For patients with stage IVa at diagnosis, non--extrapleural pneumonectomy, incomplete or no resection, and histological subtype may contribute to a poorer prognosis in patients diagnosed with pleural dissemination. The number of disseminated pleural nodules remains controversial and may be correlated with resectability.

Comparative the impact intraoperative phrenic nerve sacrifice on prognosis patients with thymoma

OBJECTIVES

Complete removal of the tumor and surrounding tissue is the most important prognostic factor such as survival after surgery. When the tumor invades the phrenic nerve, the impact of intraoperative phrenic nerve sacrifice on the short- and long-term prognosis of patients is not clear. This study aims to explore the differences in prognosis between patients with malignant thymoma with and without phrenic nerve sacrifice during surgery, as well as analyze related factors.

METHODS

A total of 209 patients who underwent thymoma resection in the Department of Thoracic Surgery at our hospital from February 2006 to November 2022 were collected for retrospective analysis. The groups were divided into two according to the presence or absence of intraoperative phrenic nerve sacrifice. A comparative analysis was conducted on postoperative complications, long-term survival recurrence between the two groups. Cox regression was used to analyze the factors related to the differences in short- and long-term prognosis between two groups.

RESULTS

29.6% of patients developed phrenic nerve sacrifice during thymoma surgery. Compared to patients without phrenic nerve sacrifice, the long-term survival rate was lower (P = 0.031). The independent risk factors for reduced long-term survival were intraoperative phrenic nerve sacrifice, secondary postoperative complications, and modified Masaoka staging III/IV.

CONCLUSION

Our data show that nearly one-third of patients develop phrenic nerve sacrifice during complete resection of thymoma. Phrenic nerve sacrifice has significant impact on short-term complications and long-term survival. Secondary postoperative complications and modified Masaoka staging III/IV are also risk factors for reduced long-term survival.

Spatial Distribution Patterns of Pleural Dissemination in Patients With Thymoma and Survival Analysis

Background: Thymoma is a common malignancy with low incidence, and pleural metastases are common pattern of recurrence. It is necessary that the spatial location of pleural metastatic lesions be analyzed. This study aimed to analyze the spatial distribution patterns of pleural dissemination in patients with thymoma and evaluate the variables that influence the survival of pleural metastasis in this population. Methods: This retrospective study investigated hospital admissions of patients diagnosed with pleural metastasis from thymoma. The spatial distribution pattern and visualization of the pleural metastases were analyzed after establishing a coordinate system. We further analyzed the survival and influencing factors in patients with pleural metastases from thymoma. Results: The analysis included 56 patients with a cumulative count of 365 pleural metastases, with 351 metastases from Zones 1-5 finally included in the analysis. The spatial distribution of the 285 initially diagnosed pleural metastases was significantly concentrated in Zones 3 and 4 near the lateral half of the spine (56.5%), followed by Zone 5 (17.5%). Collectively, these two components accounted for 74.0% (211/285) of all initial metastatic lesions. The survival rates at 5 years for those who underwent surgery versus nonsurgical treatment were 68.3% and 37.1%, respectively (p=0.015). Univariate Cox regression analysis showed that surgical intervention reduced the risk of death by 61%. Conclusions: The distribution of pleural metastatic lesions exhibited a nonuniform pattern, primarily concentrated on the spinal aspect below the aortic arch of the costal pleura and the spinal aspect of the diaphragmatic pleura.

Pathological tumor long-to-short axis ratio as a prognostic factor in patients with thymic epithelial tumors

Background

Thymic epithelial tumors (TETs) exhibit irregular shapes reflective of the heterogeneity in tumor growth and invasive properties. We aimed to identify the prognostic value of the pathological tumor long‐to‐short axis (L/S) ratio in TETs.

Methods

A retrospective study was performed on patients with TETs who underwent extended thymectomy between January 1999 and December 2019 in our institute. Patients were divided into two groups according to the threshold of the L/S ratio. Overall survival (OS) and progression‐free survival (PFS) were evaluated by Kaplan‐Meier analysis. The independent prognostic factors of TETs were identified by multivariate analysis. The performance of prediction models for the above survival outcomes with and without the L/S ratio was evaluated using an integrated time‐dependent area under the curve (iAUC).

Results

Eligible patients were divided into two groups based on higher (n = 42) and lower (n = 94) L/S ratios according to a threshold value of 1.39. A significant difference was found between the two groups only in disease progression (p = 0.001). Poorer survival outcomes were found from Kaplan‐Meier curves in the higher L/S ratio group (p < 0.05). In the multivariable analysis, the L/S ratio showed significant effects on OS and PFS (p < 0.05). The performance of models with the L/S ratio was better than that without the L/S ratio in predicting survival outcomes.

Conclusions

The pathological tumor L/S ratio is an independent prognostic factor for OS and PFS in patients with TETs, and an L/S ratio >1.39 is associated with worse survival outcomes.

Therapeutic options in thymomas and thymic carcinomas

INTRODUCTION

Radical surgery is the best therapeutic option for thymic malignancies. However, patients with advanced or recurrent thymic malignancies often require chemotherapy or radiotherapy. Since thymic malignancies are rare cancers, the efficacy and safety of treatments have been verified based on small Phase 2 trials or retrospective studies.

AREA COVERED

We comprehensively reviewed the treatment strategies for thymic malignancies, including surgery, radiotherapy, and pharmacotherapy, including cytotoxic chemotherapy, molecular-targeted therapy, and immunotherapy. Additionally, we reviewed specific situations, such as pleural dissemination, central nervous system metastasis, and paraneoplastic syndrome.

EXPERT OPINION

Cytotoxic chemotherapy remains the standard option in pharmacotherapy. However, multikinase inhibitors, such as sunitinib and lenvatinib, and immune checkpoint inhibitors including pembrolizumab have been developed to treat thymic carcinomas. Now, a Phase 2 study is evaluating whether lenvatinib plus pembrolizumab benefits patients with type B3 thymoma or thymic carcinoma. Phosphatidylinositol 3-kinase/AKT/ mammalian target of rapamycin inhibitors may contribute to disease control and octreotide scan is only applicable to somatostatin analogues. Although the genomic characteristics of thymic malignancies have been analyzed, few actionable mutations have been detected in general. The development of a treatment strategy using combination pharmacotherapy is anticipated.

Pleural Invasion Depth of Disseminated Nodules in Patients with Stage IVa or Recurrent Thymoma: Assessment, Curative Impact, and Surgical Outcomes

BACKGROUND

Thymoma patients with pleural dissemination are difficult to manage, and their treatment strategy remains undefined. This study aimed to investigate the clinicopathologic features of these patients, focusing on the association between the depth of pleural invasion and prognosis.

METHODS

Between 2003 and 2019, the study identified 120 disseminated lesions in 20 thymoma patients. Seven patients had de novo stage IVa thymoma and 13 were recurrent cases. Extrapleural pneumonectomy was performed for 8 patients and debulking surgery for 12 patients. Invasion depth of pleural tumors was classified into two groups: when the disseminated tumors invaded the pleura beneath the elastic layer, the tumor was diagnosed as Da, and when the disseminated tumors invaded the pleura beyond the elastic layer, the tumor was diagnosed as Db.

RESULTS

Of 120 nodules, 31 (26%), found in eight patients with recurrent malignancies, were classified as Db. The pathologic status of the surgical margin (PSM) was positive in eight patients, seven of whom had Db nodules. The 5-year overall survival (OS) rate was 100% in the Da group and 75% in the Db group (P = 0.02). The 5-year progression-free survival (PFS) rate was 66.7% in the Da group and 25% in the Db group (P = 0.02). Cox univariate analysis showed that PFS was significantly influenced by the depth of invasion (P = 0.04) and PSM (P = 0.03).

CONCLUSION

Depth of pleural invasion may influence survival outcomes for thymoma patients with pleural dissemination. The patients in this study with Da-disseminated nodules had an increased probability of a longer OS and PFS and tended to achieve negative PSM compared with the patients with Db.

Elevated serum CYFRA 21-1 level as a diagnostic marker for thymic carcinoma

Background

No useful tumor markers have been identified for the diagnosis of thymic carcinomas. Serum cytokeratin 19 fragment, measured using the CYFRA 21‐1 immunoassay, is used as a tumor marker for squamous cell carcinomas in various malignant tumors. Here, we evaluated the value of CYFRA 21‐1 in diagnosing thymic carcinoma.

Methods

We retrospectively reviewed 94 patients with pathological diagnoses of thymic carcinoma or thymoma (32 and 62 patients, respectively) who were referred to our departments between January 2000 and March 2019. Primary outcomes included tumor marker levels and their diagnostic accuracy.

Results

Patients with thymic carcinoma were significantly more likely to be male (thymic carcinoma, 68.8%; thymoma, 40.3%; p = 0.02), have an advanced TNM stage (p < 0.01), and a significantly higher CYFRA 21‐1 level than those with thymoma (thymic carcinoma: median = 4.2 ng/ml; interquartile range [IQR] = 2.1–6.1 ng/ml vs. thymoma: median = 1.2 ng/ml; IQR = 0.9–1.7 ng/ml; p < 0.01). Receiver operating characteristic curves demonstrated that the area under the curve for CYFRA 21‐1 to distinguish thymic carcinoma from thymoma was 0.86 (95% confidence interval [CI]: 0.74–0.93; cutoff = 2.7 ng/ml; sensitivity = 68.8%; specificity = 95.2%). Multivariable analysis demonstrated that CYFRA 21‐1 (odds ratio = 25.6; 95% CI: 4.6–141.6; p < 0.01) was an independent predictor for thymic carcinoma after adjusting for TNM stage.

Conclusions

Serum CYFRA 21‐1 level may help in diagnosing thymic carcinoma.

Long-term survival in thymic carcinoma with postoperative pleural dissemination

BACKGROUND

We report a patient with thymic squamous cell carcinoma who underwent multiple rounds of surgical resection and definitive radiotherapy for both primary tumor and postoperative recurrence. However, the patient remains well and healthy 18 years after initial diagnosis. Since long-term survival after postoperative recurrence of thymic carcinoma is extremely rare, we also present her immunohistochemical staining results, which suggested indolent disease.

CASE PRESENTATION

A 42-year-old woman with thymic squamous cell carcinoma underwent en bloc resection of the tumor and thymus gland. Pleural dissemination was noted in the right thoracic cavity 3, 10, and 16 years postoperatively. Where possible, the nodules were resected surgically: during the postoperative 3rd and 16th years. Definitive radiotherapy was administered for all nodules that could not be excised during the postoperative 3rd and 10th years. Disease-free survival is 25 months.

CONCLUSIONS

Local control of pleural dissemination may be beneficial in the treatment of postoperative recurrence of thymic carcinoma in limited cases of indolent disease.

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.

The role of surgery in the management of locally advanced and metastatic thymoma: a narrative review

Thymic epithelial tumors (TETs) are rare neoplasms. While treatment guidelines for early stage TETs are well established, treatment for advanced and locally invasive and metastatic TETs (Masaoka stage IVa/IVb) is varied. Many studies examining outcomes in this patient population are single institution, retrospective studies with small sample sizes. Further complicating study of advanced TETs is that Masaoka stage IVa/IVb describes a wide variety of disease heterogeneity, and includes both thymoma and thymic carcinoma. Thus, recommendations for treatment strategies vary widely. Surgical resection with an R0 resection is a key component of treatment for early stage TETs, however the utility of surgery and appropriate surgical approach for patients with locally invasive disease is debated and ranges from local metastasectomy to extrapleural pneumonectomy (EPP). The use of multimodal therapies, including adjuvant and neoadjuvant radiation and chemoradiation, are important for patients with locally advanced disease, however identifying patients who would most benefit from each strategy has been challenging. In this review we examined the literature to provide treatment strategies for advanced TETs. Surgery with an R0 resection should be attempted in all risk appropriate patients. Multimodal therapies are likely beneficial to patients particularly with locally advanced disease, and neoadjuvant therapies may increase likelihood of R0 resection. Further investigation is necessary to identify optimal treatment strategies for patients with locally advanced TETs.

Tubeless video-assisted thoracoscopic surgery in mediastinal tumor resection

Background

It has been reported that tubeless video-assisted thoracoscopic surgery (tubeless-VATS) is feasible and safe for thoracic diseases. Herein, we compared the early outcomes of mediastinal lesion resection between the tubeless and traditional VATS.

Methods

Clinical data of all patients who underwent thoracoscopic mediastinal tumor resection were retrospectively collected. The study involved two groups: tubeless and traditional VATS group. Propensity score matching (PSM) was applied to eliminate the population bias. Intraoperative and postoperative variables were compared among matched cohorts.

Results

In total, 43 patients in the tubeless group and 231 patients in the traditional VATS group were included. After 1:1 PSM, baseline characteristics were comparable. Anesthesia time (177.63 vs. 202.53 min; P=0.004) was shorter in tubeless group, while operation time (90.95 vs. 101.47 min; P=0.109) was similar. Overall, the total postoperative morbidity rate was similar in the two groups (15% vs. 12.5%; P=0.556). Specially, 4/43 patients in tubeless VATS group need to be re-put chest tubes postoperatively. A significant lower similar level of visual analogue scale score was observed in tubeless VATS group (1.73±0.48 vs. 3.41±0.87, P<0.001) in postoperative day 1. Meanwhile, the number of patients using postoperative opioid analgesia was also lower in tubeless VATS group (22.88% vs. 48.38%, P=0.016). Furthermore, hospital duration after surgery (2.58 vs. 5.47 days; P=0.002) was shorter in tubeless group.

Conclusions

Compared with traditional VATS, tubeless VATS for mediastinal tumor may shorten the anesthesia time, decrease postoperative pain and fasten postoperative recovery in carefully selected patients.

Surgical treatment strategies for invasive thymoma

A thymoma is a common anterior thymus mediastinal tumor composed of atypical epithelial tumor cells, though the morbidity rate is lower as compared to other types of thoracic malignancy such as lung cancer and lung metastasis from another primary cancer. As a result, clinical data regarding thymomas have not been well discussed as compared to those of other carcinomas. Also, because of the low morbidity rate and insufficient clinical experience, oncological characteristics and clinical treatment options are poorly understood. Surgical complete resection is the most reliable option for clinical treatment of a thymoma. This tumor can easily develop adjacent to several different structures and nearby organs, such as the pericardium, lungs, and great vessels, which are easily invaded when the size is large, and a combined resection is then needed. When en bloc resection is considered to be difficult based on evaluation with preoperative modalities, induction chemotherapy followed by surgery is recommended. Moreover, when pleural dissemination is revealed during pre- or peri-operative procedures, volume reduction surgery has been reported by several groups to extend prognosis. On the other hand, in cases with a small-sized tumor, a minimally invasive surgical procedure, such as video-assisted thoracic surgery (VATS) or robotic-assisted thoracic surgery (RATS), is usually selected. Because of the wide variety of cases with thymoma, a deliberate strategy and skillful techniques are necessary for effectual surgical treatment. In this review, we discuss strategies that have been shown to be effective for treating patients with early and advanced thymoma, including those with involved adjacent organs.

Spontaneous ventilation video-assisted thoracic surgery for mediastinal tumor resection in patients with pulmonary function deficiency

BACKGROUND

Whether non-intubated spontaneous ventilation video-assisted thoracoscopic surgery (SV-VATS) is a safe procedure remains controversial for mediastinal tumor patients with impaired lung function. Herein, we assessed feasibility of SV-VATS in lung function deficiency patients underwent mediastinal tumor resection.

METHODS

From December 2015 to February 2020, 32 mediastinal tumor patients with impaired lung function (preoperative forced expiratory volume in 1 second <70% of the predicted value) were retrospectively collected. Patients were divided into two groups: SV-VATS group and mechanical ventilation VATS (MV-VATS) group. Intraoperative and postoperative variables were compared between two cohorts.

RESULTS

Fifteen patients (46.88%) underwent SV-VATS and 17 patients (53.12%) were performed with MV-VATS. The most common causes of lung function deficiency were smoking (81.25%) and COPD (71.88%). Patients in the SV-VATS group had similar blood loss (20.63 vs. 18.76 mL, P=0.417) with MV-VATS group. The anesthesia time (217.51 vs. 197.76 min; P=0.343) and surgery time (141.23 vs. 132.36 min; P=0.209) were also similar between groups. Five people suffered postoperative complications in each group, in which 1 patient underwent MV-VATS was transferred to intensive care unit (ICU) because of prolonged extubation owing to hypoxia. There was no difference on chest tube removal time (2.6 vs. 2.3 days; P=0.172) or hospital duration (5.03 vs. 4.74 days; P=0.297) in patients underwent SV-VATS and MV-VATS.

CONCLUSIONS

SV-VATS is safe and provides similar short-term results to MV-VATS for mediastinal tumor resection in patients with limited pulmonary function.

Surgical management of thymic epithelial tumors

Resection is the mainstay of treatment for thymic epithelial tumors (TETs), with complete removal of the tumor and involved organs being the ultimate aim. The choice of surgical approach plays a major role in defining treatment success, and the optimal choice of method should thus provide an adequate surgical view to achieve complete tumor resection. While median sternotomy is considered the gold standard for access to the mediastinum, several minimally invasive approaches to thymectomy have been described, including video-assisted robotic-assisted thymectomy, although the oncological outcomes of that procedure remain unclear. A multimodal approach incorporating chemotherapy or chemoradiotherapy followed by extended surgery may improve resectability and outcomes for patients with advanced TETs. Surgical debulking is also reportedly acceptable for invasive thymoma because of its potential for achieving favorable outcomes. Re-resection is an acceptable option for patients with recurrent thymoma after initial resection, and repeat resection for recurrent pleural dissemination seems effective. Here, the literature on current clinical practices in the surgical management and treatment of TETs is reviewed.

Nonintubated Spontaneous Ventilation Offers Better Short-term Outcome for Mediastinal Tumor Surgery

BACKGROUND

Nonintubated spontaneous ventilation video-assisted thoracoscopic surgery (NI-VATS) has been investigated to reduce the adverse effects of tracheal intubation, mechanical ventilation, and general anesthesia in several thoracic diseases. We comparatively assess the comparison between NI-VATS vs intubated anesthesia VATS (I-VATS) on early outcomes of mediastinal lesion resection.

METHODS

Patients who underwent VATS resection for a mediastinal tumor between December 2015 and September 2018 were retrospectively included for analysis. Patients were divided into two groups according to anesthesia ventilation type: NI-VATS and I-VATS. Propensity score matching was applied to eliminate population bias. Intraoperative and postoperative variables were compared.

RESULTS

A total of 198 patients was included; 75 patients underwent NI-VATS and 123 patients underwent I-VATS. After propensity score matching, both anesthesia time (173.81 vs 227.37 minutes, P < .001) and operation time (82.82 vs 133.49 minutes, P < .001) were shorter in the NI-VATS group. Bleeding (51.80 mL vs 56.73 mL, P = .90) and postoperative morbidity (10.9% vs 15.6%, P = .57) were similar between groups. Chest tube duration (1.11 vs 1.54 days, P = .04) was shorter in the NI-VATS group. Hospital duration after surgery (3.15 vs 5.35 days, P < .001) was shorter in the NI-VATS group. D-dimer after surgery was significantly higher in both groups, but NI-VATS decreased the change (577 vs 1624 μg/L, P < .001). Furthermore, a decrease in the use of postoperative opioids analgesics was seen in the NI-VATS group (31% vs 51%, P = .023).

CONCLUSIONS

Mediastinal tumor resection is safe and feasible under NI-VATS. Better short-term outcomes suggest NI-VATS facilitates a more rapid recovery. Further multicenter prospective randomized investigation is warranted.