Proton and carbon ion beam treatment with active raster scanning method in 147 patients with skull base chordoma at the Heidelberg Ion Beam Therapy Center-a single-center experience

Strahlenther Onkol. 2023 Feb;199(2):160-168. doi: 10.1007/s00066-022-02002-4. Epub 2022 Sep 23.

Abstract

Background: This study aimed to compare the results of irradiation with protons versus irradiation with carbon ions in a raster scan technique in patients with skull base chordomas and to identify risk factors that may compromise treatment results.

Methods: A total of 147 patients (85 men, 62 women) were irradiated with carbon ions (111 patients) or protons (36 patients) with a median dose of 66 Gy (RBE (Relative biological effectiveness); carbon ions) in 4 weeks or 74 Gy (RBE; protons) in 7 weeks at the Heidelberg Ion Beam Therapy Center (HIT) in Heidelberg, Germany. The median follow-up time was 49.3 months. All patients had gross residual disease at the beginning of RT. Compression of the brainstem was present in 38%, contact without compression in 18%, and no contact but less than 3 mm distance in 16%. Local control and overall survival were evaluated using the Kaplan-Meier Method based on scheduled treatment (protons vs. carbon ions) and compared via the log rank test. Subgroup analyses were performed to identify possible prognostic factors.

Results: During the follow-up, 41 patients (27.9%) developed a local recurrence. The median follow-up time was 49.3 months (95% CI: 40.8-53.8; reverse Kaplan-Meier median follow-up time 56.3 months, 95% CI: 51.9-60.7). No significant differences between protons and carbon ions were observed regarding LC, OS, or overall toxicity. The 1‑year, 3‑year, and 5‑year LC rates were 97%, 80%, and 61% (protons) and 96%, 80%, and 65% (carbon ions), respectively. The corresponding OS rates were 100%, 92%, and 92% (protons) and 99%, 91%, and 83% (carbon ions). No significant prognostic factors for LC or OS could be determined regarding the whole cohort; however, a significantly improved LC could be observed if the tumor was > 3 mm distant from the brainstem in patients presenting in a primary situation.

Conclusion: Outcomes of proton and carbon ion treatment of skull base chordomas seem similar regarding tumor control, survival, and toxicity. Close proximity to the brainstem might be a negative prognostic factor, at least in patients presenting in a primary situation.

Keywords: Bragg peak; C12; Heavy ion; High LET; Notochordal sarcoma; Particle therapy.

MeSH terms

  • Carbon / therapeutic use
  • Chondrosarcoma* / drug therapy
  • Chondrosarcoma* / etiology
  • Chordoma* / diagnostic imaging
  • Chordoma* / drug therapy
  • Chordoma* / radiotherapy
  • Female
  • Head and Neck Neoplasms*
  • Heavy Ion Radiotherapy* / adverse effects
  • Heavy Ion Radiotherapy* / methods
  • Humans
  • Ions
  • Male
  • Proton Therapy*
  • Protons
  • Skull Base / pathology
  • Skull Base Neoplasms* / diagnostic imaging
  • Skull Base Neoplasms* / drug therapy
  • Skull Base Neoplasms* / radiotherapy

Substances

  • Protons
  • Ions
  • Carbon