The Clinical outcomes following pencil beam scanning proton therapy for skull base chordoma and chondrosarcoma: a single-institution experience

Authors

  • Tomasz Skóra Maria Skłodowska – Curie National Research Institute of Oncology, Kraków Branch, Kraków, Poland
  • kamila rawoj´c Maria Skłodowska – Curie National Research Institute of Oncology, Kraków Branch, Kraków, Poland
  • Joanna Anioł Maria Skłodowska – Curie National Research Institute of Oncology, Kraków Branch, Kraków, Poland
  • Tomasz Banaś Maria Skłodowska – Curie National Research Institute of Oncology, Kraków Branch, Kraków, Poland
  • Anna Cepiga Maria Skłodowska – Curie National Research Institute of Oncology, Kraków Branch, Kraków, Poland
  • Agnieszka Chrostowska Maria Skłodowska – Curie National Research Institute of Oncology, Kraków Branch, Kraków, Poland
  • Adrianna Chudyba Maria Skłodowska – Curie National Research Institute of Oncology, Kraków Branch, Kraków, Poland
  • Magdalena Garbacz Cyclotron Centre Bronowice, The Henryk Niewodniczański Institute of Nuclear Physics, Polish Academy of Sciences, Kraków, Poland
  • Eleonora Góra Maria Skłodowska – Curie National Research Institute of Oncology, Kraków Branch, Kraków, Poland
  • Damian Kabat Maria Skłodowska – Curie National Research Institute of Oncology, Kraków Branch, Kraków, Poland
  • Emilia Krzywonos Maria Skłodowska – Curie National Research Institute of Oncology, Kraków Branch, Kraków, Poland
  • Tomasz Mikołajski Cyclotron Centre Bronowice, The Henryk Niewodniczański Institute of Nuclear Physics, Polish Academy of Sciences, Kraków, Poland; Faculty of Medical Sciences in Zabrze, Medical University of Silesia, Katowice, Poland
  • Jadwiga Nowak-Sadzikowska Maria Skłodowska – Curie National Research Institute of Oncology, Kraków Branch, Kraków, Poland
  • Anna Patla Maria Skłodowska – Curie National Research Institute of Oncology, Kraków Branch, Kraków, Poland
  • Elżbieta Pluta Maria Skłodowska – Curie National Research Institute of Oncology, Kraków Branch, Kraków, Poland
  • Antoni Rucinski Cyclotron Centre Bronowice, The Henryk Niewodniczański Institute of Nuclear Physics, Polish Academy of Sciences, Kraków, Poland
  • Konrad Urbanek Maria Skłodowska – Curie National Research Institute of Oncology, Kraków Branch, Kraków, Poland
  • Dominika Wojton-Dziewońska Maria Skłodowska – Curie National Research Institute of Oncology, Kraków Branch, Kraków, Poland
  • Mariusz Wszołek Maria Skłodowska – Curie National Research Institute of Oncology, Kraków Branch, Kraków, Poland
  • Renata Kopeć Cyclotron Centre Bronowice, The Henryk Niewodniczański Institute of Nuclear Physics, Polish Academy of Sciences, Kraków, Poland
  • Kamil Kisielewicz Maria Skłodowska – Curie National Research Institute of Oncology, Kraków Branch, Kraków, Poland

DOI:

https://doi.org/10.2340/1651-226X.2026.45297

Keywords:

• Skull base tumors • Chordoma • Chondrosarcoma • Proton therapy • Pencil beam scanning • Intensity modulated proton therapy (IMPT) • Radiotherapy outcomes • Local control • Artificial intelligence in radiotherapy • Augmented reality • Radiation toxicity • Precision oncology • Translational research • Dose escalation • Hypofractionation

Abstract

Background: Chordomas and chondrosarcomas of the skull base are rare, locally aggressive tumors that pose significant therapeutic challenges due to their proximity to critical anatomical structures. While maximal safe surgical resection remains the cornerstone of management, the infiltrative nature of these tumors often precludes radical excision, necessitating adjuvant radiotherapy. Given their relative radioresistance, high-dose radiotherapy exceeding 70 Gray Relative Biological Effectiveness (GyRBE) is required to achieve durable local control. This study evaluated long-term outcomes and toxicity following pencil beam scanning (PBS) proton therapy in patients with skull base chordoma and chondrosarcoma.
Methods: We retrospectively analyzed 76 patients (50 chordoma, 26 chondrosarcoma) treated with curative-intent PBS between 2016 and 2020. Median prescribed doses were 74.0 GyRBE for chordomas and 70.0 GyRBE for chondrosarcomas. Clinical endpoints included overall survival (OS), local failure-free survival (LFFS), distant metastasis-free survival (DMFS), and toxicity graded according to CTCAE v5.0.
Results: At a median follow-up of 70.2 months, 5-year OS, LFFS, and DMFS for the entire cohort were 84.0, 86.9, and 92.7%, respectively. Local control was numerically higher in chondrosarcoma (96.1%) than in chordoma (81.9%; p = 0.116). Tumor contact with the optic apparatus or brainstem was associated with worse OS (p = 0.0034 and p = 0.0151, respectively) and proximity to the optic pathways correlated with poorer local control (p = 0.0182). Grade ≥ 3 late toxicity occurred in 9.2% of patients, predominantly hearing impairment and temporal lobe necrosis.
Conclusions: PBS achieves excellent local control and survival with an acceptable safety profile in skull base chordoma and chondrosarcoma. Our findings align with ongoing efforts toward dose intensification, hypofractionation, and particle selection. Moreover, emerging integration of artificial intelligence for contouring, treatment adaptation, and toxicity prediction, along with augmented reality-assisted positioning and patient education, promises to further enhance treatment precision and outcomes. Through long-term follow-up and engagement with international research initiatives, our institution contributes to the global advancement of biologically guided, high-precision radiotherapy for rare skull base malignancies.

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Published

2026-07-31

How to Cite

Skóra, T., rawoj´c, kamila, Anioł, J., Banaś, T., Cepiga, A., Chrostowska, A., … Kisielewicz, K. (2026). The Clinical outcomes following pencil beam scanning proton therapy for skull base chordoma and chondrosarcoma: a single-institution experience. Acta Oncologica, 65, 679–688. https://doi.org/10.2340/1651-226X.2026.45297

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Vol. 65 (2026): Acta Oncologica

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Original article

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Copyright (c) 2026 Tomasz Skóra, kamila rawoj´c, Joanna Anioł, Tomasz Banaś, Anna Cepiga, Agnieszka Chrostowska, Adrianna Chudyba, Magdalena Garbacz, Eleonora Góra, Damian Kabat, Emilia Krzywonos , Tomasz Mikołajski , Jadwiga Nowak-Sadzikowska, Anna Patla, Elżbieta Pluta, Antoni Rucinski, Konrad Urbanek, Dominika Wojton-Dziewońska , Mariusz Wszołek, Renata Kopeć, Kamil Kisielewicz

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