Treatment Of Chordomas And Chondrosarcomas With Cyberknife Robotic Hypofractionated Radiosurgery: A Single Institution Experience

IntroductionThe aim of this study is to determine the efficacy and safety of CyberKnife (R) (Accuray, Inc., Sunnyvale, CA) hypofractionated radiosurgery (HfRS) in the treatment of chordomas and chondrosarcomas.MethodsA total of 24 patients retrospectively identified with chordomas (19 patients) or chondrosarcomas (five patients) were treated between 2012 and 2019 with conventional external beam radiation therapy (EBRT) as monotherapy or an adjuvant, rescue, or combination therapy. Tumors were located in the skull base (75%) and vertebral spine (25%). Of these, 19 patients underwent previous partial resection and four patients received previous EBRT (60-74 Gy). Exclusive or rescue HfRS (20 patients) was administered in live fractions with a median dose of 37.5 Gy (30-40 Gy). Combined tomotherapy-EBRT treatment (median dose: 54 Gy) and HfRS (16.5-30 Gy in 3-12 fractions) were performed in four patients with bulky chordomas.ResultsThe median follow-up from HfRS was 28 months. During clinical follow-up, no deaths were registered with overall survival (OS) of l00% and the actuarial local recurrence-free survival (LRFS) was 93% at one year, 85% at three years, and 68% at five years. Acute toxicity related to HfRS was present in a single patient.ConclusionsIt is seen that HfRS is effective and safe for chordomas and chondrosarcomas, with rates of LRFS comparable to other radiation modalities.