Optimizing stereotactic radiosurgery in patients with recurrent or residual craniopharyngiomas

Abstract

Stereotactic radiosurgery (SRS) is an important management strategy for residual and recurrentCraniopharyngiomas. The current study evaluated the factors which affected tumor control and complications in craniopharyngioma SRS. MethodsThis study includes 53 consecutive patients who underwent single-session SRS for recurrent or residual craniopharyngiomas. The median age was 41 years with 28 male and 25 females. The median tumor volume was 0.63 cm 3 and median margin dose was 12 Gy (range, 9-25 Gy). ResultsThe overall 3-, 5-, and 10-year survival rates were 97.8%, 92.7% and 88.5%. The overall 3-, 5-, and 10-year tumor control rates were 81.0%, 72.1%, and 53.4%. In univariate analysis, >3 mm distance from optic structures (p=0.002), only solid or cystic tumor type (p=0.037), and >12 Gy to ≥85% of the tumor (p<0.001) were signi cantly associated with improved tumor control. In multivariate analysis, only solid or cystic tumor type, (p=0.034), and >85% of the tumor receiving >12 Gy (p=0.004) were signi cantly associated with better tumor control. When >85% of the tumor received >12 Gy the tumor control rates at 3-, 5-, and 10-year were 100%, 93.3%, and 93.3%. Higher conformity index was not associated with better tumor control. ConclusionsThe tumor control rates after recurrent or residual craniopharyngiomas SRS were improved by ensuring that at least 85% of the tumor received >12 Gy even when the distance between the tumor and the optic system is <3 mm. This concept refutes the conformity theory that a high conformity index is a critical feature of effective SRS.

Effects of two different radiotherapies for craniopharyngiomas using stereotactic radiosurgery/ stereotactic radiotherapy or fractionated stereotactic radiotherapy

“…In that study, almost half of the patients had a tumor recurrence, resulting in treatment failure during the long-term period due to the reduced marginal dose of ≤10 Gy when the tumors adhered to the optic apparatus. Similar outcomes were reported in other studies in which higher margin dose (≥12 Gy) enables better local tumor control,[ 20 ] but sufficient distance to the optic nerve (≥2 mm, ≥3 mm or 3–5 mm)[ 6 , 7 , 19 , 20 ] is necessary to achieve that.…”

“…GKS has been reported to be an effective management option and studies have suggested 5-year progression-free survival rate of 72.1–90.3%. [ 4 , 16 , 20 , 26 ] However, these studies focused on one treatment and the comparison of outcomes from other radiation strategies and criteria for selecting treatment plans have not been established. GKS was mainly performed in a single fraction and it can threaten visual function when the tumor was touching or compressing the optic nerve.…”

“…No patients developed a new pituitary deficiency because few pediatric cases were reported in this report. Moreover, visual disturbance generally occurs within 3 years after radiation,[ 17 , 20 ] and our follow-up period may be too short to evaluate it.…”

“…Both stereotactic radiosurgery (SRS). [ 4 , 16 , 20 ] and fractionated stereotactic radiotherapy (FSRT). [ 2 , 6 , 23 ] for residual or recurrent craniopharyngiomas have been proven to be effective in the long-term overall and recurrence-free survival.…”

The Role of Surgical Approaches in the Multi-Modal Management of Adult Craniopharyngiomas

“…Larger case series with long-term follow-up in patients undergoing stereotactic radiosurgery for previously operated tumors have demonstrated tumor control rates of between 60.8-76% at 5 years and 42.6-60.2% at 10 years [81][82][83][84][85][86][87]. However, radiation dosing must be carefully planned as adequate doses greater than 12 Gy have been shown to yield better local control [88] but maximum dosing exceeding 35 Gy may lead to tissue toxicity [85]. Adverse radiation rates in larger case series have ranged from 6.2-10.9%, most commonly hypopituitarism, followed by visual deficits and hypothalamic obesity [83,86].…”