Postoperative radiotherapy for completely resected thymoma: Differing roles in masaoka stage II and stage III disease

PURPOSE

The efficacy of radiotherapy for treating thymomas is unclear. The goal of this study was to analyze overall survival (OS) and disease-free survival (DFS) among thymoma patients to determine the impact of postoperative radiotherapy (PORT) on thymoma outcomes.

METHODS

Recorded cases of thymoma at Xinqiao Hospital were retrospectively analyzed from 1991 to 2019. Data on stage II and III thymomas were extracted from medical records. This study evaluated OS and DFS and compared outcomes between surgery and surgery-plus-radiation groups. The Kaplan-Meier method and Cox regression analysis were used to compare DFS and OS for these groups.

RESULTS

Of the 205 patients included in the current study, 142 (69.3%) presented with stage II disease and 63 (30.7%) presented with stage III disease. The median follow-up was 84.3 months. PORT did not statistically significantly improve OS (P = 0.613) and DFS (P = 0.445) in stage II thymoma patients (compared with surgery alone). However, our subgroup analysis showed a statistically significant difference in DFS in patients with stage III thymoma (P = 0.044).

CONCLUSION

Although the routine use of postoperative radiotherapy in patients with thymoma does not appear warranted, patients with stage III thymoma may benefit from adjuvant radiation. These findings, if confirmed, will provide valuable information to guide medical decision-making for thymoma treatment.

Optimal delineation of the clinical target volume for thymomas in the post-resection setting: A multi-center study

BACKGROUND

The definition of the clinical target volume (CTV) for post-operative radiotherapy (PORT) for thymoma is largely unexplored. The aim of this study was to analyze the difference in CTV delineation between radiation oncologists (RTO) and surgeons.

METHODS

This retrospective multi-center study enrolled 31 patients who underwent PORT for a thymoma from five hospitals. Three CTVs were delineated per patient: one CTV by the RTO, one CTV by the surgeon (blinded to the results of the RTO) and a joint CTV after collaboration. Volumes (cm³), Hausdorff distances (HD) and Dice similarity coefficients (DSC) were analyzed.

RESULTS

RTO delineated significantly bigger CTVs than surgeons (mean: 93.9 ± 63.1, versus 57.9 ± 61.3 cm³, p = 0.003). Agreement was poor between RO and surgeons, with a low mean DSC (0.34 ± 0.21) and high mean HD of 4.5 (±2.2) cm. Collaborative delineation resulted in significantly smaller volumes compared to RTO (mean 57.1 ± 58.6 cm³, p < 0.001). A mean volume of 18.9 (±38.1) cm³ was included in joint contours, but missed by RTO. Conversely, a mean volume of 55.7 (±39.9) cm³ was included in RTO's delineations, but not in the joint delineations.

CONCLUSIONS

To the best of our knowledge, this is the first study investigating CTV definition in thymoma. We demonstrated a significant variability between RTO and surgeons. Joint delineation prompted revisions in smaller CTV as well as favoring the surgeons' judgement, suggesting that surgeons provided relevant insight into other risk areas than RTO. We recommend a multidisciplinary approach to PORT for thymomas in clinical practice.

Thymoma with osseous metaplasia; a case report with a brief literature review

INTRODUCTION AND IMPORTANCE

The thymus is a primary lymphatic organ within the mediastinum that plays an essential role in developing and maintaining cell-mediated immunity. The current study aims to report a case of intra-tumoral osseous metaplasia of the thymus gland, which is an infrequent phenomenon.

CASE PRESENTATION

A 43-year-old male presented with weakness and easy fatigability for 2 months. The patient had an elevated anti-acetylcholinesterase antibody (19.5 nmole/L). Magnetic resonance imaging showed a round, capsulated, enhanced mass in the anterior mediastinum measuring 5.5 × 3.5 cm, suspecting thymoma. The patient underwent plasmapheresis three times in one week, under general anesthesia, in a supine position, sternotomy was performed, and the thymoma was totally resected.

DISCUSSION

Thymomas are known to occur in all age groups with the peak of nearly between 35 and 70 years with the median age of 54 years. The sex distribution of thymoma is approximately equal with slight predilection of women in old age groups. However, among all reported cases of thymomas with osseous metaplasia, the majorities are female. The significance of this ossification is still to be clarified.

CONCLUSION

Although it is rare, secondary changes in thymoma may occur including calcification and ossification.

Outcomes of surgical reconstruction of the superior vena cava syndrome in patients with locally advanced thymomas

The aim of the study: to study and demonstrate the potential and technical aspects of the surgical treatment of locally advanced thymus tumours with the tumour infiltrate affecting superior vena cava and its branches. Methods. 56 patients with locally advanced thymomas complicated by SVCS were study. The control group included 30 patients with SVCS were treated with conventional techniques, while the experimental group included 26 patients who underwent a novel bypass surgery developed by us. Results. Based on our observations, patients tolerated these surgeries much better. The venous bypass was mandatorily complemented with cytoreduction. Auriculo-jugular (left and right) and auriculo-subclavian (left and right) bypasses were used in our observations Complications in the post-operative period were reported from the experimental group and included auriculo-subclavian bypass thrombosis, post-operative complications were reported in the control group including haemorrhage from the sternotomy wound in 1 (3.3 %) case, superior vena cava thrombosis in 2 (6.6 %) cases, pneumonia in 2 (6.6 %) cases and thromboembolism of small pulmonary arteries in 2 (6.6 %) cases. Post-operative lethality in the study groups was reported in the control and in the experimental group. Total lethality rate was 8.9 % (5 patients). The relative risk of complications and lethal outcome was calculated for patients from both groups. It was found that the risk of complications was twice as high in the control group as in the experimental group (standard error of relative risk equals 0.64), whereas the risk of lethal outcome increased by a factor of 3.5 in the control group (standard error of relative risk equals 1.09) Conclusion. It has been established that the superior vena cava syndrome in patients with locally advanced thymoma is an emergency condition whose surgical correction must be personalised depending on the anatomic and topographic classification of SVC lesion types. It is known that an obligatory pre-condition of the perioperative period in this category of patients is an adequate vascular approach to the superior vena cava system. The first mandatory step of the radical surgery in patients with locally advanced thymomas with SVC invasion should be the auriculo-jugular and auriculo-subclavian bypasses, which can reduce the relative risk of post-operative complications by a factor of the risk of lethal by a factor of 3.5.

A Practical Approach to Managing Patients With Myasthenia Gravis-Opinions and a Review of the Literature

When the diagnosis of myasthenia gravis (MG) has been secured, the aim of management should be prompt symptom control and the induction of remission or minimal manifestations. Symptom control, with acetylcholinesterase inhibitors such as pyridostigmine, is commonly employed. This may be sufficient in mild disease. There is no single universally accepted treatment regimen. Corticosteroids are the mainstay of immunosuppressive treatment in patients with more than mild MG to induce remission. Immunosuppressive therapies, such as azathioprine are prescribed in addition to but sometimes instead of corticosteroids when background comorbidities preclude or restrict the use of steroids. Rituximab has a role in refractory MG, while plasmapheresis and immunoglobulin therapy are commonly prescribed to treat MG crisis and in some cases of refractory MG. Data from the MGTX trial showed clear evidence that thymectomy is beneficial in patients with acetylcholine receptor (AChR) antibody positive generalized MG, up to the age of 65 years. Minimally invasive thymectomy surgery including robotic-assisted thymectomy surgery has further revolutionized thymectomy and the management of MG. Ocular MG is not life-threatening but can be significantly disabling when diplopia is persistent. There is evidence to support early treatment with corticosteroids when ocular motility is abnormal and fails to respond to symptomatic treatment. Treatment needs to be individualized in the older age-group depending on specific comorbidities. In the younger age-groups, particularly in women, consideration must be given to the potential teratogenicity of certain therapies. Novel therapies are being developed and trialed, including ones that inhibit complement-induced immunological pathways or interfere with antibody-recycling pathways. Fatigue is common in MG and should be duly identified from fatigable weakness and managed with a combination of physical therapy with or without psychological support. MG patients may also develop dysfunctional breathing and the necessary respiratory physiotherapy techniques need to be implemented to alleviate the patient's symptoms of dyspnoea. In this review, we discuss various facets of myasthenia management in adults with ocular and generalized disease, including some practical approaches and our personal opinions based on our experience.

Volumetric modulated arc therapy versus intensity-modulated proton therapy in the postoperative irradiation of thymoma

BACKGROUND

To investigate the role of intensity-modulated proton therapy (IMPT) compared to volumetric modulated arc therapy (VMAT) for the radiation treatment of thymoma cancer.

METHODS

Twenty patients were retrospectively planned for IMPT [with (IMPT_R1 or IMPT_R2 according to the approach adopted) and without robust optimization] and VMAT. The results were compared according to dose-volume metrics on the clinical and planning target volumes (CTV and PTV) and the main organs at risk (heart, breasts, lungs, spinal cord and oesophagus). Estimates of the excess absolute risk (EAR) of secondary cancer induction were determined for the oesophagus, the breasts and the composite lungs. For the heart, the relative risk (RR) of chronic heart failure (CHF) was assessed.

RESULTS

IMPT and VMAT plans resulted equivalent in terms of target coverage for both the CTV and the PTV. The CTV homogeneity index resulted in 0.03 ± 0.01 and 0.04 ± 0.01 for VMAT and all IMPT plans, respectively. The conformality index resulted in 1.1 ± 0.1 and 1.2 ± 0.1 for VMAT and all IMPT plans. The mean dose to the breasts resulted in 10.5 ± 5.0, 4.5 ± 3.4, 4.7 ± 3.5 and 4.6 ± 3.4 Gy for VMAT, IMPT, IMPT_R1 and IMPT_R2. For the lungs, the mean dose was 9.6 ± 2.3, 3.5 ± 1.5, 3.6 ± 1.6 and 3.8 ± 1.4 Gy; for the heart: 8.7 ± 4.4, 4.3 ± 1.9, 4.5 ± 2.0 and 4.4 ± 2.4 Gy and for the oesophagus 8.2 ± 3.5, 2.2 ± 3.4, 2.4 ± 3.6 and 2.5 ± 3.5 Gy. The RR for CHF was 1.6 ± 0.3 for VMAT and 1.3 ± 0.2 for IMPT (R1 or R2). The EAR was 3.6 ± 0.v vs 1.0 ± 0.6 or 1.2 ± 0.6 (excess cases/10,000 patients year) for the oesophagus; 17.4 ± 6.5 vs 5.7 ± 3.2 or 6.1 ± 3.8 for the breasts and 24.8 ± 4.3 vs 8.1 ± 2.7 or 8.7 ± 2.3 for the composite lungs for VMAT and IMPT_R, respectively.

CONCLUSION

The data from this in-silico study suggest that intensity-modulated proton therapy could be significantly advantageous in the treatment of thymoma patients with particular emphasis to a substantial reduction of the risk of cardiac failure and secondary cancer induction. Robust planning is a technical pre-requisite for the safety of the delivery.

Value of Adjuvant Radiotherapy for Thymoma with Myasthenia Gravis after Extended Thymectomy

Background:

The co-existence of myasthenia gravis (MG) and thymoma makes the surgical treatment more complicated and adjuvant radiation more controversial. The aim of this study was to investigate adjuvant radiotherapy for thymoma with MG after extended thymectomy.

Methods:

A total of 181 patients with both MG and thymoma were recruited between 2003 and 2014 at Tongren Hospital, China. Among all the patients, 157 patients received radiation therapy after surgery (Group A); whereas the other 24 patients did not receive radiation therapy (Group B). According to the time that patients started mediastinal radiation therapy, we subdivided the 157 patients in Group A into subgroups (1-month subgroup, n = 98; 2-month subgroup, n = 7; and 3-month subgroup, n = 52). We then compared the effect of the mediastinal radiation therapy across these different groups using the survival rate, the rate of postoperative myasthenic crisis, and the complete stable remission (CSR) rate as the primary endpoints.

Results:

There was a significant difference in the occurrence of postoperative myasthenic crisis between 1-month subgroup and Group B (χ² = 4.631, P = 0.031). The rates of reaching CSR were 32.6% in 1-month subgroup, 25% in 3-month subgroup, and 22.7% in Group B, respectively. The overall survival rates of 1-month subgroup, 3-month subgroup, and Group B were 88.8%, 83.3%, and 77.3%, respectively. Analysis on the Kaplan-Meier survival curves demonstrated that within 8 years after surgery, there was no significant difference in aspects of overall survival and disease-free survival between 1-month subgroup and Group B, and between 3-month subgroup and Group B; over 8 years after surgery, the disease-free survival rates in 1-month subgroup, 3-month subgroup and Group B were 79.4%, 70.6%, and 55.3%, respectively.

Conclusions:

Adjuvant radiation within 1 month after extended thymectomy may be helpful in controlling postoperative MG, such as decreasing the possibility of postoperative myasthenic crisis, and raising cumulative probabilities of reaching CSR.

Postoperative radiotherapy and tumor recurrence after complete resection of stage II/III thymic tumor: a meta-analysis of cohort studies

BACKGROUND

Whether postoperative radiotherapy (PORT) is effective for reducing the recurrence risk in patients who received complete resection of the stage II or III thymic tumors has not been determined. A meta-analysis was performed by combining the results of all available controlled trials.

METHODS

PubMed, Cochrane's Library, and the Embase databases were searched for studies which compared the recurrence data for patients with complete resection of the stage II or III thymic tumors assigned to an observing group, or a PORT group. A random effect model was applied to combine the results.

RESULTS

Nineteen studies, all designed as retrospective cohort studies were included. These studies included 663 patients of PORT group and 617 patients of observing group. The recurrence rate for the patients in PORT group and observing group were 12.4% and 11.5%, respectively. Results of our study indicated that PORT has no significant influence on recurrent risk in patients with stage II or III thymic tumor after complete resection (odds ratio 1.02, 95% confidence interval 0.55-1.90, P=0.96). When stratified by stages, our meta-analyses did not indicate any significant effects of PORT on recurrent outcomes in either the stage II or the stage III patients. Moreover, subsequent analysis limited to studies only including patients with thymoma or thymic carcinoma also did not support the benefits of PORT on recurrent outcomes.

CONCLUSION

Although derived from retrospective cohort studies, current evidence did not support any benefit of PORT on recurrent risk in patients with complete resection of the stage II or III thymic tumors.

A Case Series of Patients With Autoimmune Myasthenia Gravis in Association With Invasive Thymoma

OBJECTIVES

In some patients, autoimmune myasthenia gravis (MG) is associated with thymic hyperplasia or thymoma, and in some patients the thymoma is invasive. Little is known about the clinical course of subjects who present with MG and are found to have invasive thymoma.

METHODS

We reviewed the patients at our clinic with MG and invasive thymoma, and have described their clinical features.

RESULTS

Six MG patients were diagnosed with invasive thymoma. The subjects had extensive multimodal therapy. Two subjects died from uncontrolled neuromuscular respiratory failure despite aggressive immunosuppression, 2 subjects had other autoimmune disorders (Morvan syndrome and polymyositis), and 2 subjects are controlled on immunosuppression.

CONCLUSIONS

Patients with invasive thymoma and MG can have a poor outcome, with difficulty in controlling myasthenic symptoms and can have other clinically important autoimmune diseases.

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.