Stereotactic body radiotherapy for metastatic and recurrent ewing sarcoma and osteosarcoma.

Background. Radiotherapy has been utilized for metastatic and recurrent osteosarcoma and Ewing sarcoma (ES), in order to provide palliation and possibly prolong overall or progression-free survival. Stereotactic body radiotherapy (SBRT) is convenient for patients and offers the possibility of increased efficacy. We report our early institutional experience using SBRT for recurrent and metastatic osteosarcoma and Ewing sarcoma. Methods. We reviewed all cases of osteosarcoma or ES treated with SBRT between 2008 and 2012. Results. We identified 14 patients with a total of 27 lesions from osteosarcoma (n = 19) or ES (n = 8). The median total curative/definitive SBRT dose delivered was 40 Gy in 5 fractions (range, 30-60 Gy in 3-10 fractions). The median total palliative SBRT dose delivered was 40 Gy in 5 fractions (range, 16-50 Gy in 1-10 fractions). Two grade 2 and 1 grade 3 late toxicities occurred, consisting of myonecrosis, avascular necrosis with pathologic fracture, and sacral plexopathy. Toxicity was seen in the settings of concurrent chemotherapy and reirradiation. Conclusions. This descriptive report suggests that SBRT may be a feasible local treatment option for patients with osteosarcoma and ES. However, significant toxicity can result, and thus systematic study is warranted to clarify efficacy and characterize long-term toxicity.