Results of spot-scanning proton radiation therapy for chordoma and chondrosarcoma of the skull base: The Paul Scherrer Institut experience

Conclusion: Spot-scanning PT offers high tumor control rates of skull base chordoma and CS. These results compare favorably to other combined proton-photon or carbon ion irradiation series. Observed toxicity was acceptable. Younger age (≤40 years) was a favorable prognostic factor of PFS. These preliminary results are encouraging but should be confirmed during a longer follow-up.