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Table 2 Factors Prognostic of LC, OS and PFS

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

Factors n (%) LC PFS OS
5y (%) P 5y (%) P 5y (%) P
Age <  55 12 (50) 90 0.824 90 0.551 100 0.046
>  55 12 (50) 81 73 74
Gender male 10 (42) 76 0.268 69 0.270 90 0.692
female 14 (58) 92 92 83
Untreated or recurrence untreated 17 (71) 86 0.453 80 0.633 87 0.429
recurrence 7 (29) 86 86 86
Proximity of tumor and brainstema 6 (25) 100 0.215 100 0.205 80 0.738
+ 18 (75) 81 75 81
Surgery 10 (42) 57 0.048* 55 0.028* 68 0.012*
+ 14 (58) 100 100 100
Ion type PT 11 (46) 80 0.752 72 0.187 73 0.060
CIT 13 (54) 92 92 100
GTV volume <  17.0 ml 12 (50) 91 0.776 91 0.482 91 0.059
≥ 17.0 ml 12 (50) 77 70 82
GTV Dminb <  55 Gy (RBE) 13 (54) 81 0.289 73 0.195 74 0.059
≥ 55 Gy (RBE) 11 (46) 90 90 100
  1. LC local control, PFS progression-free survival, OS overall survival, PT proton therapy, CIT carbon ion therapy, GTV gross target volume, Dmin minimum dose
  2. *Statistically significant
  3. aOverlap of the PTV with the brainstem
  4. bMinimum dose of GTV was standardised as equivalent dose in 2Gy with α/β = 2 using LQ model