Treatment outcomes of proton or carbon ion therapy for skull base chordoma: a retrospective study

Radiation Oncology

Table 2 Factors Prognostic of LC, OS and PFS

Factors		n (%)	LC		PFS		OS
Factors		n (%)	5y (%)	P	5y (%)	P	5y (%)	P
Age	< 55	12 (50)	90	0.824	90	0.551	100	0.046
Age	> 55	12 (50)	81	0.824	73	0.551	74	0.046
Gender	male	10 (42)	76	0.268	69	0.270	90	0.692
Gender	female	14 (58)	92	0.268	92	0.270	83	0.692
Untreated or recurrence	untreated	17 (71)	86	0.453	80	0.633	87	0.429
Untreated or recurrence	recurrence	7 (29)	86	0.453	86	0.633	86	0.429
Proximity of tumor and brainstem^a	–	6 (25)	100	0.215	100	0.205	80	0.738
Proximity of tumor and brainstem^a	+	18 (75)	81	0.215	75	0.205	81	0.738
Surgery	–	10 (42)	57	0.048^*	55	0.028^*	68	0.012^*
Surgery	+	14 (58)	100	0.048^*	100	0.028^*	100	0.012^*
Ion type	PT	11 (46)	80	0.752	72	0.187	73	0.060
Ion type	CIT	13 (54)	92	0.752	92	0.187	100	0.060
GTV volume	< 17.0 ml	12 (50)	91	0.776	91	0.482	91	0.059
GTV volume	≥ 17.0 ml	12 (50)	77	0.776	70	0.482	82	0.059
GTV Dmin^b	< 55 Gy (RBE)	13 (54)	81	0.289	73	0.195	74	0.059
GTV Dmin^b	≥ 55 Gy (RBE)	11 (46)	90	0.289	90	0.195	100	0.059

LC local control, PFS progression-free survival, OS overall survival, PT proton therapy, CIT carbon ion therapy, GTV gross target volume, Dmin minimum dose
^*Statistically significant
^aOverlap of the PTV with the brainstem
^bMinimum dose of GTV was standardised as equivalent dose in 2Gy with α/β = 2 using LQ model

ISSN: 1748-717X