Thymoma is one of the most common primary tumors in the anterior mediastinum, representing a group of diseases originating from different thymic epithelial cells, characterized by unique clinical and pathological features, often accompanied by various paraneoplastic syndromes. During the “Multidisciplinary Oncology Committee” session held at the 2023 European Lung Cancer Congress (ELCC), several experts discussed the treatment strategies for Stage III thymoma based on a case study. Dr. Andreas Rimner from Memorial Sloan Kettering Cancer Center presented on “The Timing of Radiotherapy in the Treatment of Stage III Thymoma.” In an interview with Oncology Frontier, Andreas Rimner shares insights into the role of radiotherapy in the treatment of Stage III thymoma.

Could you please discuss the treatment strategies for Stage III thymoma and which patients require systemic treatment?

Dr. Rimner: Stage III thymoma is typically treated with a comprehensive approach, including surgery, systemic therapy, and radiotherapy. Systemic therapy or drug treatment, such as chemotherapy, is usually administered before surgery, primarily to shrink the tumor before surgical resection.

Administering 3-4 cycles of neoadjuvant chemotherapy is a common treatment strategy for thymoma. However, the decision regarding the necessity of neoadjuvant therapy involves ongoing discussions between medical oncologists and surgeons. Whether neoadjuvant chemotherapy is required largely depends on whether the patient can tolerate chemotherapy and whether the surgeon can successfully resect the tumor. The decision to use neoadjuvant therapy should be based on the potential benefit it offers in improving the likelihood of successful tumor removal.

Can you discuss the role of radiotherapy in the treatment of Stage III thymoma and when radiotherapy intervention is necessary?

Dr. Rimner: Radiotherapy is needed in various situations during the treatment of Stage III thymoma. Radiotherapy can be used for a minority of patients who are not candidates for surgery due to advanced age or other medical comorbidities that make surgery too risky. In these cases, radiotherapy can serve as a definitive or curative treatment and can be used alone or in conjunction with chemotherapy.

Radiotherapy is more commonly used as postoperative treatment for Stage III thymoma, meaning that after surgery, if the surgical margins are positive or if the tumor was incompletely resected based on oncological principles, radiotherapy is usually employed. Some research data also suggest that postoperative radiotherapy can help improve patient outcomes as an adjuvant treatment in cases of incomplete resection. However, there are also research findings indicating that even in cases of complete resection (R0 resection), postoperative radiotherapy can enhance disease-free and overall survival.

For each patient, the discussion should revolve around the “risk versus benefit of postoperative radiotherapy.” Since there is currently no Level I evidence from prospective randomized studies, all available evidence is based on retrospective studies and large database research. Even though existing evidence strongly suggests that patients can benefit from postoperative radiotherapy, discussions with individual patients are essential to provide them with relevant information, allowing them to decide whether postoperative radiotherapy is the right choice for them.