The Role of Adjuvant Radiation Therapy for Resected Stage III Thymoma: A Population-Based Study

doi:10.1016/j.athoracsur.2012.03.004

The Annals of Thoracic Surgery

Volume 93, Issue 6, June 2012, Pages 1822-1829

Presented at the Fifty-eighth Annual Meeting of the Southern Thoracic Surgical Association, San Antonio, TX, Nov 9–12, 2011.

https://doi.org/10.1016/j.athoracsur.2012.03.004 Get rights and content

Background

Because of the rarity of the disease and long survival of most patients, the role of adjuvant radiation therapy in patients with surgically resected stage III thymoma is unclear, and few prospective studies are available. The objective was to evaluate the impact of postoperative radiation therapy after resection of stage III thymoma.

Methods

The Surveillance, Epidemiology, and End Results (SEER) database was queried for all patients with stage III thymoma who underwent surgical therapy and survived more than 30 days after diagnosis. Survival was estimated with the Kaplan-Meier method. The hazard ratio for death was determined using a Cox proportional hazard model.

Results

There were 476 patients with stage III thymoma identified who underwent surgical therapy, did not receive preoperative radiotherapy, and had complete SEER records with regard to radiation treatment. Postoperative radiation therapy was given to 322 patients (67.6%). Patients who received postoperative radiation therapy were younger and had a higher rate of debulking surgery than patients who did not. Patients receiving postoperative radiation had a median overall survival of 127 months (95% confidence interval, 100.9 to 153.1) compared with 105 months (95% confidence interval, 76.9 to 133.1) in patients treated with surgery alone (p = 0.038). However, in multivariate analysis, postoperative radiation was not a significant factor affecting overall survival. Disease-specific survival was significantly improved in the adjuvant radiation group, and in multivariate analysis, improved outcomes were associated with postoperative radiation (p = 0.049).

Conclusions

In this large population-based study, most patients with stage III thymoma were treated with adjuvant radiation. Postoperative radiation was associated with improved disease-specific survival, but not improved overall survival.

Section snippets

Material and Methods

The University of Pittsburgh Institutional Review Board approved this study, and informed consent was waived. The SEER database is sponsored by the National Cancer Institute and has been used to track cancer incidence and patient survival since 1973. The SEER database currently covers approximately 28% of the US population and captures 98% of all cancer cases within the surveyed geographic areas. We used the SEER 17 Registry including the Hurricane Katrina Impacted Louisiana Cases for this

Results

We identified 662 patients with stage III thymoma in the SEER database. The majority (n = 516) underwent surgical resection. Data on radiation therapy was available for 513 patients. We elected to include only patients with stage III thymoma who underwent surgery and whose SEER records contained complete data on staging, radiation therapy, and surgery (n = 499). Of the patients who underwent surgical resection, 18 (3.5%) were treated with preoperative radiation therapy, 322 (64.5%) were treated

Comment

In this large population-based study, postoperative radiation therapy was found to be an important factor associated with improved disease-specific survival in patients operated on for Masaoka stage III thymoma. In multivariate analysis, postoperative adjuvant radiation was not significantly associated with improved overall survival.

Patients receiving radiation therapy were younger and had a higher rate of debulking surgery. This may indicate a provider bias in recommending radiation therapy to

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Cited by (55)

Additional Evidence for Postoperative Radiation Therapy on Thymic Carcinoma
2024, Journal of Thoracic Oncology
Postoperative Radiation Therapy for Thymic Carcinoma: An Analysis of the International Thymic Malignancy Interest Group/European Society of Thoracic Surgeons Database
2024, Journal of Thoracic Oncology
R0 resection and radiation therapy have been associated with improved overall survival (OS) in patients with thymic carcinoma (TC). Here, we analyzed which subgroups of patients derive the greatest benefit from postoperative radiation therapy (PORT).
Clinical, pathologic, treatment, and survival information of 462 patients with TC from the International Thymic Malignancy Interest Group/European Society of Thoracic Surgeons database were analyzed. Variables included age, sex, continent of treatment, paraneoplastic syndrome, carcinoma subtype, tumor size, pathologic Masaoka stage, resection status, and use of chemotherapy. OS was the primary end point using the Kaplan-Meier method. Time to recurrence (TTR) was the secondary end point using a competing risk analysis. A 3-month landmark analysis was performed.
PORT was associated with a significant OS benefit (5-y OS 68% versus 53%, p = 0.002). In patients with R0 resection, PORT was associated with increased OS for advanced (stages III–IV, p = 0.04), but not early (stages I–II, p = 0.14) stage TC. In patients with an R1/2 resection of advanced-stage TC, PORT was associated with significantly longer OS (5-y OS 53% versus 38%; p < 0.001). Subset analyses did not reveal clear associations of PORT with TTR. On multivariable analysis, lower pathologic stage, PORT, and R0 resection status were associated with an OS benefit, whereas only higher age and lower pathologic stage had an association with longer TTR.
In the largest individual patient data set on patients with TC reported to date, PORT was associated with a meaningful OS benefit in patients with advanced-stage TC after an R0 or R1/2 resection.
Dosimetric analysis of beam arrangement for intensity-modulated radiation therapy in the postoperative irradiation of thymoma
2023, Radiation Physics and Chemistry
This study aimed to investigate the dosimetric effect of various beam arrangements (BAs), for intensity-modulated radiotherapy (IMRT) in female thymoma patients. Six-field IMRT plans with three different BAs, named IMRT_CA, IMRT_CS, and IMRT_NC were created for each patient. The couch angles of all fields were selected at 0°, which made the fields coplanar in the axial plane in IMRT_CA plans. The couch angles of all fields were selected to be 90°, which makes the fields coplanar in the sagittal plane in IMRT_CS plans. The couch angles of the four fields and two fields were selected as 90° and 0°, respectively in IMRT_NC plans. Plans were compared in terms of dose homogeneity, conformity, and OAR doses. IMRT_CS plans created with coplanar beams in the sagittal plane could offer significant advantages in terms of breast and lung sparing. IMRT_CS may be useful for young female thymoma patients to reduce the risk of developing a second cancer in the breast. In addition, it should be considered that IMRT_CS contributes approximately 1 Gy to the mean heart dose.
Prognostic factors and role of postoperative radiotherapy in surgically resected thymomas
2023, JTCVS Open
To investigate the prognostic factors in and role of postoperative radiotherapy (PORT) for surgically resected thymomas.
A total of 1540 patients with pathologically confirmed thymomas undergoing resection between 2000 and 2018 were identified retrospectively from the SEER (Surveillance, Epidemiology, and End Results) database. Tumors were restaged as local (limited to thymus), regional (invasion to mediastinal fat and other neighboring structures), or distant stage. Disease-specific survival (DSS) and overall survival (OS) were estimated by the Kaplan–Meier method and the log-rank test. Adjusted hazard ratios (HRs) with 95% CIs were calculated by Cox proportional hazards modeling.
Tumor stage and histology were independent predictors of both DSS (regional: HR, 3.711; 95% CI, 2.006-6.864; distant: HR, 7.920; 95% CI, 4.061-15.446; type B2/B3: HR, 1.435; 95% CI, 1.008-2.044) and OS (regional: HR, 1.461; 95% CI, 1.139-1.875; distant: HR, 2.551; 95% CI, 1.855-3.509; type B2/B3: HR, 1.409; 95% CI, 1.153-1.723). For patients with regional stage and type B2/B3 thymomas, PORT was associated with better DSS after thymectomy/thymomectomy (HR, 0.268; 95% CI, 0.099-0.727), but the association was not significant after extended thymectomy (HR, 1.514; 95% CI, 0.516-4.44). Among patients with lymph node metastases, those who received PORT (HR, 0.372; 95% CI, 0.146-0.949), chemotherapy (HR, 0.843; 95% CI, 0.303-2.346), or both (HR, 0.296, 95% CI, 0.071-1.236) had a better OS.
The extent of invasion and tumor histology were independent predictors of worse survival following surgical resection of thymoma. Patients with regional invasion and type B2/B3 thymoma who undergo thymectomy/thymomectomy may benefit from PORT, while patients with nodal metastases may benefit from multimodal therapy, including PORT and chemotherapy.
Postoperative radiotherapy for completely resected thymoma: Differing roles in masaoka stage II and stage III disease
2022, Asian Journal of Surgery
Citation Excerpt :
However, several studies have shown a local control advantage of PORT in treating advanced thymoma.10–12 However, other authors have found no conclusive advantage of PORT in stage II and III patients.13–15 Hence, the impact of PORT on survival after resection of stage II and III thymomas remains unclear.
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.
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.
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).
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
2021, Radiotherapy and Oncology
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.
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.
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.
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.

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Original articleGeneral thoracicThe Role of Adjuvant Radiation Therapy for Resected Stage III Thymoma: A Population-Based Study

Background

Methods

Results

Conclusions

Section snippets

Material and Methods

Results

Comment

J Thorac Oncol

J Thorac Oncol

Int J Radiat Oncol Biol Phys

Ann Thorac Surg

Ann Thorac Surg

J Thorac Oncol

J Thorac Oncol

J Thorac Cardiovasc Surg

J Thorac Cardiovasc Surg

Int J Radiat Oncol Biol Phys

Ann Thorac Surg

Ann Thorac Surg

Original article
General thoracic
The Role of Adjuvant Radiation Therapy for Resected Stage III Thymoma: A Population-Based Study