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

Table 2 Analysis of prognostic factors related to local control after RT

	Univariate testing			Multivariate testing
Parameter	p-value	HR	95% CI	p-value	HR	95% CI
EQD2 (Gy)	0.13	0.95	0.90–1.01	0.14	0.96	0.90–1.02
Therapy situation (primary vs. recurrent tumor)	< 0.001	4.25	1.99–9.09	< 0.001	4.55	2.06–10.08
GTV (ml)	0.59	1.21	0.60–2.46	0.16	1.70	0.81–3.57
Treatment approach (C12 vs. C12 + Ph)	0.49	1.29	0.63–2.64	NA	NA	NA

Abbreviations: HR Hazard ratio, 95% CI 95% confidence interval, EQD2 Cumulative equivalent radiation dose, GTV Gross tumor volume, C12 Carbon ions, Ph Photons, NA Not analyzed

ISSN: 1748-717X