P14.20.A GAMMA KNIFE RADIOSURGERY FOR PAPILLARY CRANIOPHARYNGIOMA AFTER SURGERY: A SINGLE-CENTER STUDY ON TUMOR CONTROL AND PREDICTORS OF RECURRENCE

Abstract BACKGROUND Papillary craniopharyngioma (PCP) is a distinct histopathological subtype of craniopharyngioma with unique clinical, radiological, and molecular characteristics compared to the adamantinomatous variant. While Gamma Knife radiosurgery (GKRS) is an established modality for residual or recurrent craniopharyngiomas, limited data are available regarding its efficacy specifically in PCP. This study aimed to assess tumor control after GKRS in surgically treated PCP patients and to identify prognostic factors for recurrence. MATERIAL AND METHODS A retrospective review was conducted of 32 patients with histologically confirmed PCP who underwent GKRS at Beijing Tiantan Hospital between August 2002 and March 2025 following surgical resection. Clinical and radiological data were analyzed. Tumor progression was defined radiographically. Progression-free survival (PFS) was calculated using the Kaplan-Meier method. Univariate and multivariate Cox proportional hazards models were used to evaluate potential predictors of recurrence. RESULTS The median clinical follow-up was 49.05 months (mean, 70.34 months; range, 1.48-272.68 months). Radiological follow-up (available in 28 patients) had a median duration of 33.80 months. Tumor recurrence occurred in 10 patients (31.25%) with a median time to recurrence of 22.5 months. One-, 3-, and 5-year PFS rates were 90.6%, 81.25%, and 71.9%, respectively. Univariate analysis identified tumor volume, number of isocenters, and post-GKRS visual change as significant predictors of recurrence (P < 0.05). On multivariate analysis, subjective visual deterioration after GKRS was an independent risk factor for recurrence (OR 25.15, 95% CI 1.45-5.41, P = 0.001), while visual improvement did not significantly differ from stable vision. Post-treatment visual outcomes included improvement in 6.25%, stability in 62.5%, and deterioration in 31.25% of patients. One death occurred in the recurrence group. Most recurrences were managed with repeat GKRS or surgery. CONCLUSION GKRS offers reasonable long-term tumor control for PCP following surgical resection. Post-radiosurgical subjective visual decline may indicate early tumor recurrence and warrants close follow-up.