Optimizing stereotactic radiosurgery in patients with recurrent or residual craniopharyngiomas

Purpose Stereotactic 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. Methods This 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). Results The 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. Conclusions The 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.