Optimizing Stereotactic Radiosurgery in Patients With Recurrent or Residual Craniopharyngiomas

Abstract

PurposeStereotactic radiosurgery (SRS) is an important management strategy for residual and recurrent Craniopharyngiomas. 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 cm3 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 significantly 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 significantly 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.…”

Craniopharyngioma surgery for rhinologists

“…As technology progresses, new techniques for management of craniopharyngioma will evolve as well. This increase in treatment options will likely result in expansion of multidisciplinary management of this tumor, especially with the evolution of other techniques such as stereotactic radiosurgery, which can be used as an adjunct to surgery or in patients unwilling or unable to undergo surgery [52][53][54]. For those patients unable to tolerate surgery, cysto-ventricular catheter placement has also been explored as an option to improve mass effect on optic pathways by using minimally invasive methods to stereotactically place catheters that connect cystic craniopharyngiomas to the ventricular system for drainage [55].…”