Fig. 5From: High-dose carbon-ion based radiotherapy of primary and recurrent sacrococcygeal chordomas: long-term clinical results of a single particle therapy centerOverall survival (OS) was estimated using the Kaplan - Meier method. Comparison was made between patients with a planning target volume (PTV) of > 1109 ml vs. <= 1109 ml (p = 0.0001, log-rank test)Back to article page