Radiotherapy for Thymoma and Thymic Carcinoma

doi:10.1016/j.hoc.2008.03.012

Hematology/Oncology Clinics of North America

Volume 22, Issue 3, June 2008, Pages 489-507

https://doi.org/10.1016/j.hoc.2008.03.012 Get rights and content

The role of radiotherapy for patients who have thymic neoplasms remains unclear. The low incidence of thymic malignancies, excellent outcome with complete resection, and limited body of evidence obfuscate the role of radiation therapy within the current multidisciplinary management of disease. Nonetheless, existing literature reports and novel radiotherapy techniques show increasing potential for integration of radiotherapy into the standard therapeutic milieu for carefully selected patient subpopulations.

Section snippets

Radiotherapy for Thymoma

The role of radiation therapy in the management of malignant thymoma remains controversial. Recommendations for adjuvant radiation run the gambit. Some investigators have recommended adjuvant radiation therapy for all presentations regardless of stage or completeness of resection [1], [2]. Given that Masaoka stage I thymomas have such a low recurrence rate after an R0 resection, typically 2% to 3% [3], which radiation is unlikely to improve upon, some have proposed adjuvant radiation therapy

Radiotherapy for Thymic Carcinoma

For thymic carcinomas, as with thymomas, surgical extirpation remains the mandatory cornerstone of frontline therapeutic intervention. However, for thymic carcinoma, radiotherapy is almost universally offered, owing to the markedly poorer prognosis associated with the disease [44]. Multiple small series have detailed outcomes with radiotherapy, with no consensus in terms of radiotherapy dose, order of therapy, or radiochemotherapy regimen.

Definitive data regarding the potentially beneficent

Technical Considerations for Radiotherapy of Thymic Tumors

Most historic radiotherapy series for thymic neoplasms provide ambiguous data regarding the treatment dose fields, prescription parameters, and doses delivered, because they include patients treated heterogeneously over different technological eras. For thymoma, it is reasonable to surmise that doses >60 Gy are required for inactivation of all extant clonogens in unresectable lesions [14], [22], [38]. For resectable disease, 45 to 50 Gy has been shown to be sufficient to eradicate disease [22].

Summary

The role of radiotherapy for patients who have thymic neoplasms remains unclear. Patients who have undergone an R0 resection, have early-stage disease, or have more favorable histology (ie, World Health Organization classification A), may not benefit routinely from adjuvant radiotherapy, For patients with de novo locally advanced disease, radiotherapy may be beneficial to reduce loco-regional recurrence, when administered in a preoperative (neoadjuvant) setting with cisplatin-based

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Cited by (14)

Impact of adjuvant radiotherapy and chemotherapy on thymoma
2024, Cancer/Radiotherapie
Thymoma is a rare tumour. The most common treatment for thymoma is surgical resection, while the use of radiotherapy and chemotherapy remains controversial.
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.
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.
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.
Les thymomes sont des tumeurs rares. La résection chirurgicale est le traitement le plus important, alors que l’utilisation de la radiothérapie et de la chimiothérapie restent controversées.
Nous avons réalisé une étude observationnelle monocentrique chez 31 patients atteints de thymome diagnostiqué de juin 2004 à juillet 2020. Nous avons analysé le devenir du patient.
À 2 et 5 ans, les taux de rechute locorégionale étaient respectivement de 96,3 % (IC à 95 % [intervalle de confiance à 95 %] : 76,5–99,5 %) et de 68,0 % (IC à 95 % : 43,8–83,5 %). La radiothérapie et la chimiothérapie ont significativement amélioré le taux de contrôle local (respectivement p = 0,0008 et 0,04) alors que la taille initiale de la tumeur plus grande avait significativement dégradé les taux de contrôle local (p = 0,04). Les taux de survie globale à 5 et 10 ans étaient de 87,1 % (IC à 95 % : 69,2–95 %) et de 81,7 % (IC à 95 % : 60,3–92,2 %). La médiane de survie globale n’a pas été atteinte. Aucun facteur favorable n’a été relevé. Pour les patients en situation de rechute, la médiane de survie globale après la rechute était de 115 mois.
Malgré les inconvénients classiques des études rétrospectives sur un petit nombre de patients, nous avons montré que la chimiothérapie et la radiothérapie complétant la chirurgie étaient efficaces et participaient à l’évolution favorable chez des patients atteints de thymome. Il convient de noter qu’un traitement agressif au moment de la rechute a donné de bons résultats chez les patients retraités.
The Role of Adjuvant Therapy in Advanced Thymic Carcinoma: A National Cancer Database Analysis
2020, Annals of Thoracic Surgery
Citation Excerpt :
Fewer than half of the surveyed clinicians recommending adjuvant therapy for R0 resected stage II thymic cancer patients, whereas more than 80% recommended adjuvant therapy for R0 resected stage III thymic cancer. Several retrospective database analyses have reported improved survival with PORT, but some retrospective reports have shown little benefits.15-17 Jackson and colleagues13 demonstrated that PORT was associated with longer OS, with the greatest relative benefits observed for stage IIB to III disease and positive margins.
There is area of controversy and variability in the recommendation for the role of adjuvant therapy after R0 resection of a Masaoka stage IIB and III thymic carcinoma. This study investigated the role of adjuvant therapy in patients who had complete surgical resection for thymic carcinoma.
Patients with stage IIB and III thymic carcinoma who underwent curative resection were queried and categorized according to Masaoka-Koga stage groups from the National Cancer Database. Patients were grouped by treatment status (surgery only or surgery followed by adjuvant therapy). Kaplan-Meier estimates of overall survival and univariate and multivariate Cox proportional hazards regression analyses were performed.
From 2004 to 2013, 632 surgical patients with stage IIB and III thymic carcinoma were selected for analysis. In stage IIB patients, the adjuvant therapy group had improved survival compared with the surgery only group (P = .01), although no survival difference was observed in patients who had R0 resection between the 2 groups (P = .59). In multivariate analysis, age (P < .001) and grade III and IV (P = .02) negatively impacted survival; the adjuvant therapy improved survival (P < .02). For stage III cancer, the adjuvant therapy group had improved survival compared with the OS group regardless of margin status. In multivariate analysis, tumor size exceeding 70 mm (P = .02) and positive margin (P < .01) negatively affected survival; adjuvant therapy improved survival (P < .01).
Adjuvant therapy showed no benefit in patients with stage IIB cancer who had R0 resection. Use of adjuvant therapy should be strongly considered for stage IIB cancer patients with positive margins and all stage III thymic cancer patients.
The Impact of Postoperative Radiotherapy for Thymoma and Thymic Carcinoma
2017, Journal of Thoracic Oncology
The optimal role for postoperative radiotherapy (PORT) for thymoma and thymic carcinoma remains controversial. We used the National Cancer Data Base to investigate the impact of PORT on overall survival (OS).
Patients who underwent an operation for thymoma or thymic carcinoma were categorized into Masaoka-Koga stage groups I to IIA, IIB, III, and IV. Patients who did not undergo an operation or those who received preoperative radiation were excluded. Kaplan-Meier estimates of OS and univariate and multivariate Cox proportional hazards regression analyses were performed. Propensity score–matched analyses were performed to further control for baseline confounders.
From 2004 to 2012, 4056 patients were eligible for inclusion, 2001 of whom (49%) received PORT. On multivariate analysis of OS in the thymoma cohort adjusted for age, WHO histologic subtype, Masaoka-Koga stage group, surgical margins, and chemotherapy administration, PORT was associated with superior OS (hazard ratio [HR] = 0.72, p = 0.001). Propensity score–matched analyses confirmed the survival advantage associated with PORT. Subset analysis indicated longer OS in association with PORT for patients with stage IIB thymoma (HR = 0.61, p = 0.035), stage III (HR = 0.69, p = 0.020), and positive margins (HR = 0.53, p < 0.001). The impact of PORT for stage I to IIA disease did not reach significance (HR = 0.76, p = 0.156).
In this large database analysis of PORT for thymic tumors, PORT was associated with longer OS, with the greatest relative benefits observed for stage IIB to III disease and positive margins. In the absence of randomized studies assessing the value of PORT, these data may inform clinical practice.
Thymoma: A population-based study of the management and outcomes for the province of British Columbia
2013, Journal of Thoracic Oncology
Citation Excerpt :
In our series, selected patients were offered postoperative radiation therapy. Although this series was unable to demonstrate a clear-cut benefit from radiation, several larger series have supported its use.20–22 The long clinical course of this disease requires careful selection for radiotherapy, given its potential for late toxicity including coronary artery disease, thyroid dysfunction, and secondary malignancies.23
Thymomas are rare neoplasms with variable clinical behavior. Our primary study aim was to analyze treatment practices and outcomes in a population-based cohort of thymoma patients. We hypothesized that stage I and II thymomas would have high cure rates with resection and adjuvant radiation, whereas locally advanced cases would benefit from multimodality therapy.
All patients, diagnosed with thymoma or thymic carcinoma in British Columbia between 1994 and 2009, were identified using the British Columbia Cancer Agency Registry. Chart review was used to collect demographic and treatment data. Detailed pathology review was performed using the World Health Organization classification.
One hundred and seventy-one patients were identified for analysis. The 5-year overall survival was 93.3%, 88.7%, 74.6%, 43.4% for stages I, II, III, and IV, respectively. Survival varied significantly among patients with thymoma compared with thymic carcinoma. In patients with stage II disease, adjuvant radiation did not confer an overall survival or recurrence-free survival benefit. Seventy-five patients had locally advanced disease. There was practice variation in treatment of these patients. Patients with thymoma undergoing trimodality treatment had a 5-year median overall survival of 80%, whereas patients with thymic carcinoma had poor outcomes despite aggressive treatment.
Survival rates in this population-based series were comparable to those in previously published reports. The ideal management of thymic tumors involves a multidisciplinary approach, particularly in locally advanced disease and selection of patients for adjuvant radiation therapy.
Entire hemithorax irradiation for Masaoka stage IVa thymomas
2012, Reports of Practical Oncology and Radiotherapy
Thymomas are rare neoplasms that have an indolent growth with a preferentially intra-thoracic dissemination pattern. Surgery is currently the standard treatment of thymomas; however radiotherapy is often used in an adjuvant setting due to a high sensitivity of these tumors to such treatment. Postoperative entire hemithoracic irradiation has been used in selected Masaoka stage IVa cases after complete surgical excision of metastatic lesions.
In the present article, the authors report three cases of Masaoka stage IVa thymoma that underwent entire hemithorax irradiation after surgical excision of metastatic lesions. The first two patients presented as stage IVa thymomas. The third case consisted of a pleural recurrence of a thymoma.
Hemithoracic irradiation with low doses has been used by different authors; the available data shows that it is a well-tolerated treatment that could potentially lead to better loco-regional control and increased overall survival.
The Role of Radiotherapy in the Management of Thymic Tumors
2011, Thoracic Surgery Clinics
Citation Excerpt :
The quantification of radiation dose distribution within the virtual model allows several treatment plannings to be compared using dose–volume histograms, which represent for each structure the volume receiving at least a certain radiation dose15 and normal tissue complication probabilities, which are available for each critical organ. Numerous radiation dose and fractionation schemes have been reported for thymoma and thymic carcinomas.14,16–23 Although thymomas have been recognized as highly radiosensitive tumors for years, the benefit of dose escalation on local control has not clearly been established.

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Radiotherapy for Thymoma and Thymic Carcinoma

Section snippets

Radiotherapy for Thymoma

Radiotherapy for Thymic Carcinoma

Technical Considerations for Radiotherapy of Thymic Tumors

Summary

J Thorac Cardiovasc Surg

Ann Thorac Surg

Ann Thorac Surg

Radiother Oncol

Int J Radiat Oncol Biol Phys

Ann Thorac Surg

Eur J Surg Oncol

Ann Thorac Surg

J Thorac Cardiovasc Surg

Int J Radiat Oncol Biol Phys

Radiother Oncol

Ann Thorac Surg

Ann Thorac Surg

Ann Thorac Surg

Ann Thorac Surg

Int J Radiat Oncol Biol Phys

Ann Thorac Surg

Int J Radiat Oncol Biol Phys

Radiother Oncol

Radiother Oncol

Ann Thorac Surg

Int J Radiat Oncol Biol Phys

Int J Radiat Oncol Biol Phys

Ann Thorac Surg

Cell

Int J Radiat Oncol Biol Phys

Eur J Cancer Clin Oncol

Int J Radiat Oncol Biol Phys

Lung Cancer

J Thorac Cardiovasc Surg

Int J Radiat Oncol Biol Phys

Ann Thorac Surg

Ann Thorac Surg