Results of salvage treatment with CyberKnife® fractioned radiosurgery in recurrent large chordoma

Aim: Chordomas and chondrosarcomas are locally destructive tumors with high progression or recurrence rates after initial multimodality treatment. This report examined the role of radiosurgery in patients who were considered inoperable after the recurrence of large chordoma disease having undergone previous surgery and/or radiotherapy.

Methods: All patients who were referred to Okmeydani Education and Research Hospital between 2012 and 2019 for treatment of recurrent or metastatic chordoma and considered not suitable for surgical treatment were included in the study. We included patients presenting with recurrent or metastatic chordoma, those who had undergone surgery and/or radiotherapy and were now considered to be surgically inoperable, patients whose tumors could lead to severe neurologic or organ dysfunction when resected, and those who underwent salvage treatments for definitive or palliative purposes with radiosurgery. After radiosurgical salvage therapy was performed on 13 patients using a CyberKnife® device, the effect of this treatment in terms of local control and survival and the factors that might affect it was investigated. Thirteen lesions were local (in-field) recurrence, and five lesions were closer to the primary tumor mass or seeding metastatic lesions. Tumor response was evaluated using the Response Evaluation Criteria for Solid Tumors (RECIST) system and volumetric analysis.

Results: The median age of the 13 patients was 59 years, and the median tumor volume of 18 lesions was 30.506 cc (R: 6884.06-150,418.519 mL). The median dose was 35 Gy (R: 17.5-47.5), the median fraction was 5 (R: 1-5), and the median biological effective dose BED_2.45 was 135 Gy (R: 63.82-231.68). The median time for radiosurgery was 30 months after the first radiotherapy and 45 months after the last surgery. The median follow-up time was 57 (R: 15-94) months. The progression-free survival was 24 months. The median survival was 33.9 months. Local control was achieved in 84.6% of patients after 1 year, and 76.9% after 2 years, with the mass shrinking or remaining stable. Survival after recurrence was 69.2% for the 1st year, 61.5% for the 2nd year, and 53.8% for the 5th year.

Conclusion: In patients with recurrent and surgically inoperable chordomas, stereotactic body radiation therapy (SBRT) is a reliable and effective treatment method. Promising result has been obtained with radiosurgery treatment under local control of patients.

Level of evidence: Diagnostic: individual cross-sectional studies with consistently applied reference standard and blinding.