Novel strategies in radiation therapy: high-dose radiotherapy for oligometastatic/oligo-progressive thymic tumors.

Oligometastatic and oligoprogressive thymic tumors are unique clinical presentations that are generally rare, yet occur with some regularity, especially in large volume centers. Close observation is often a viable option at first. Surgical resection is usually the primary local therapy approach whenever possible based on technical resectability and patient's medical operability. High-dose radiation therapy has opened more opportunities for patients who may need adjuvant radiation therapy to further optimize local tumor control in addition to surgery or definitive therapy, or in place of surgical resection when surgery may be difficult or impossible due to tumor- or patient-related factors, with high local control rates in appropriately selected patients. Especially in the metastatic setting, long-term effects of therapy and quality of life need to be balanced against local tumor control and survival endpoints. The excellent ratio of high efficacy and low risk of adverse events with high-dose stereotactic body radiation therapy and intensity-modulated radiation therapy make this radiation technique a particularly attractive treatment approach for optimizing local control and quality of life. A deep understanding of the strengths and weaknesses of each treatment modality are critical to allow for optimal use and integration of local and systemic treatment options. Here, we review the newest data for the role of local therapies in oligometastatic, oligoresidual and oligoprogressive thymic tumors with a focus on the development of high-dose radiation therapy techniques.