Radiation therapy for locally advanced thymoma. A case report

Thymoma is a tumor originating from the epithelial cells of the thymus. In cases when complete removal of the tumor is not possible due to its local spread, induction therapy, including chemotherapy, radiotherapy, or chemoradiotherapy, is administered to improve respectability.

Case presentation. We present a case of a 41-year-old male who was diagnosed with IVA type B3 thymoma (cT3N0M1a) in March 2022. Computed tomography (18.02.22) revealed a tumor in the anterior mediastinum measuring 12.0×8.0×14.5 cm with spread to the right lung and pericardium, compression of large vessels; single nodular lesions along the pleura. From 19.03.22 to 26.05.22, 4 cycles of polychemotherapy with CAP were administered. From 9.08.22 to 24.11.22, 6 cycles of chemotherapy with etoposide + cisplatin were administered. Stable disease was observed. In January, 2023, the patient visited A. Tsyb MRRC for a consultation with oncologists. Surgery was not considered as a suitable treatment option due to the spread of the disease, and radiation therapy was recommended. From 16.02.23 to 3.04.23, a conformal external beam radiation therapy was delivered to a mediastinal tumor to a total dose of 60 Gy. The treatment was well tolerated. A control examination showed tumor size reduction meaning the tumor can be surgically removed. Considering positive response to radiation therapy, satisfactory performance status and age of the patient, a decision to perform surgery was made. On September 15, 2023 the mediastinal tumor was removed with pericardial resection and its reconstruction, upper and middle lobectomy, and precision removal of parietal pleural lesions. A follow-up examination (October 2024) revealed disease progression with the appearance of nodular lesions along the diaphragmatic pleura on the right. Chemotherapy with pemetrexed was administered. Currently, the performance status of the patient is satisfactory and he is socially active.

Conclusion. Induction chemotherapy and radiotherapy for locally advanced unresectable thymoma can increase the feasibility of achieving complete tumor resection, thus improving treatment outcomes. The rarity of these tumors and the lack of standard approaches to the treatment of locally advanced thymic carcinomas determine the relevance of the problem and the need to make an optimal decision on treatment tactics in each specific clinical case.

1. Engels E.A. Epidemiology of thymoma and associated ma lignancies. J Thorac Oncol. 2010; 5(10s4): 260–65. doi: 10.1097/JTO.0b013e3181f1f62d.

2. Detterbeck F.C., Nicholson A.G., Kondo K., van Schil P., Moran C. The Masaoka-Koga stage classification for thymic malignancies: clarification and definition of terms. J Thorac Oncol. 2011; 6(7s3): 1710–16. doi: 10.1097/JTO.0b013e31821e8cff.

3. Ambrogi M.C., Aprile V., Lenzini A., Bacchin D., Mastromarino M.G., Korasidis S., Lucchi M. TNM Staging System in Thymoma: A Critical Appraisal? J Clin Med. 2024; 13(2): 610. doi: 10.3390/jcm13020610.

4. Marx A., Chan J.K.C., Chalabreysse L., Dacic S., Detterbeck F., French C.A., Hornick J.L., Inagaki H., Jain D., Lazar A.J., Marino M., Marom E.M., Moreira A.L., Nicholson A.G., Noguchi M., Nonaka D., Papotti M.G., Porubsky S., Sholl L.M., Tateyama H., Montpréville V.T., Travis W.D., Rajan A., Roden A.C., Ströbel P. The 2021 WHO Classification of Tumors of the Thymus and Mediastinum: What Is New in Thymic Epithelial, Germ Cell, and Mesenchymal Tumors? J Thorac Oncol. 2022; 17(2): 200–13. doi: 10.1016/j.jtho.2021.10.010.

5. Kondo K., Monden Y. Therapy for thymic epithelial tumors: a clinical study of 1,320 patients from Japan. Ann Thorac Surg. 2003; 76(3): 878–84; discussion 884–85. doi: 10.1016/s0003-4975(03)00555-1.

6. Ajimizu H., Sakamori Y. Narrative review of indication and management of induction therapy for thymic epithelial tumors. Mediastinum. 2024; 8: 44. doi: 10.21037/med-23-30.

7. Ruffini E., Detterbeck F., van Raemdonck D., Rocco G., Thomas P., Weder W., Brunelli A., Evangelista A., Venuta F.; European Association of Thoracic Surgeons (ESTS) Thymic Working Group. Tumours of the thymus: a cohort study of prognostic factors from the European Society of Thoracic Surgeons database. Eur J Cardiothorac Surg. 2014; 46(3): 361–68. doi: 10.1093/ejcts/ezt649.

8. Akaogi E., Ohara K., Mitsui K., Onizuka M., Ishikawa S., Mitsui T., Ogata T. Preoperative radiotherapy and surgery for advanced thymoma with invasion to the great vessels. J Surg Oncol. 1996; 63(1): 17–22. doi: 10.1002/(SICI)1096-9098(199609)63:1<17::AID-JSO4>3.0.CO;2-T.

9. Ribet M., Voisin C., Gosselin B., Pruvot F.R., Ramon P., Wallaert B., Dambron P. Les thymomes lympho-épithéliaux. Etude anatomo-clinique et thérapeutique de 113 cas [Lympho-epithelial thymoma. Anatomoclinical and therapeutic study of 113 cases]. Rev Mal Respir. 1988; 5(1): 53–60. French.

10. Korst R.J., Bezjak A., Blackmon S., Choi N., Fidias P., Liu G., Marx A., Wright C., Mock S., Rutledge J.R., Keshavjee S. Neoadjuvant chemoradiotherapy for locally advanced thymic tumors: a phase II, multiinstitutional clinical trial. J Thorac Cardiovasc Surg. 2014; 147(1): 36–44. doi: 10.1016/j.jtcvs.2013.08.061.

11. Wright C.D., Choi N.C., Wain J.C., Mathisen D.J., Lynch T.J., Fidias P. Induction chemoradiotherapy followed by resection for locally advanced Masaoka stage III and IVA thymic tumors. Ann Thorac Surg. 2008; 85(2): 385–89. doi: 10.1016/j.athoracsur.2007.08.051.

12. Fan X.W., Yang Y., Wang H.B., Xu Y., Kang M., Xie L.Y., Li L., Fang W.T., Zhao K.L., Chen H.Q., Xiang J.Q., Ung Y.C., Wong C.S., Jiang G.L., Wu K.L. Intensity Modulated Radiation Therapy Plus Etoposide/Cisplatin for Patients With Limited Advanced Unresectable Thymic Epithelial Tumors: A Prospective Phase 2 Study. Int J Radiat Oncol Biol Phys. 2020; 107(1): 98–105. doi: 10.1016/j.ijrobp.2019.12.045.