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Table 3 Analysis of prognostic factors related to overall survival after RT

From: High-dose carbon-ion based radiotherapy of primary and recurrent sacrococcygeal chordomas: long-term clinical results of a single particle therapy center

  Univariate testing Multivariate testing
Parameter p-value HR 95% CI p-value HR 95% CI
Patients’ age (y) 0.01 1.055 1.013–1.10 NA NA NA
EQD2 (Gy) 0.48 0.971 0.895–1.05 0.533 0.975 0.899–1.06
Level of proximal invasion ≥ S2 0.21 1.765 0.725–4.30 NA NA NA
Recurrent tumor 0.31 1.593 0.654–3.88 0.36 1.539 0.628–3.77
GTV (ml) 0.06 1.001 1.00–1.00 NA NA NA
PTV1 (ml) 0.04 1.001 1.00–1.00 NA NA NA
PTV2 (ml) 0.002 1.001 1.00–1.00 NA NA NA
  1. Abbreviations: HR Hazard ratio, 95% CI 95% confidence interval, EQD2 Cumulative equivalent radiation dose, GTV Gross tumor volume, PTV1 Planning target volume (boost plan), PTV2 Planning target volume (primary plan), NA Not analyzed