Dosimetric analysis of local failures in skull-base chordoma and chondrosarcoma following pencil beam scanning proton therapy

Table 2 Prognostic DVH parameters

DVH parameters and histology		Univariate analysis		Multivariate analysis
DVH parameters and histology		p value	CI	p value	CI
GTV	D95 (%)	0.05	0.59	ns	ns
GTV	V < 66 Gy_RBE	0.01	0.62	0.022	0.67
GTV	Volume	0.02	0.64	ns	ns
PTV_high	Max dose Gy_RBE	0.02	0.61	ns	ns
PTV_high	V < 66 Gy_RBE	0.03	0.63	ns	ns
PTV_high	V < 59 Gy_RBE	0.02	0.62	ns	ns
PTV_high	Volume	0.01	0.63	0.045	0.67
Histology	Chordoma versus chondrosarcoma	–	–	0.009	0.67

Italics indicate statistically significant differences
In the univariate analysis, the following DVH parameters were significantly associated with an increased risk of local recurrence: GTV D95 (p = 0.05), GTV volume receiving less than 66 Gy_RBE (V < 66Gy_RBE, p = 0.01), GTV volume (p = 0.02), PTV maximum dose (p = 0.02), PTV volume receiving less than 66 Gy_RBE (V < 66Gy_RBE, p = 0.03), PTV volume receiving less than 59 Gy_RBE (V < 59Gy_RBE, p = 0.02), PTV volume (p = 0.01). In the multivariate analysis, histology (chordoma vs chondosarcoma, p = 0.009), PTV volume (p = 0.045) and GTV (V < 66GyRBE, p = 0.022), (CI = 0.67) presented as independent prognostic factors of local tumor control

ISSN: 1748-717X