Intracavitary Yttrium-90 Colloid Therapy for Cystic Sellar Masses: A Phase II Clinical Trial With 5-Year Follow-Up

BACKGROUND AND OBJECTIVES: Stereotactic intracavitary irradiation of cystic sellar masses (CSMs) with 90-Yttrium colloid (90Y) may mitigate significant morbidity and/or recurrence rates associated with traditional microsurgical resection. In this study, we aimed to prospectively assess the long-term effect of 90Y on tumor-cyst volume, endocrine, and vision outcomes after treatment of CSMs. METHODS: We conducted a Health Canada-approved, phase II, open label, prospective clinical trial. The primary indication for treatment was clinical evidence of mass effect on initial presentation or subsequent cyst enlargement. Patients underwent right frontal stereotactic insertion of 90Y (200 Gy to the cyst wall). Cyst volumes were measured using serial MRI. Visual field (VF) assessment and hypothalamic-pituitary hormone panel were obtained. Outcomes were collected postoperatively at 3, 9, and 24 months, then annually up to 5 years. RESULTS: Twenty-two patients (55% women, mean age = 63.6 years [SD 15.4]) received 90Y. The mean follow-up was 52 months (5-113). Primary diagnoses were the following: craniopharyngioma (86%), Rathke cleft cyst (9%), and cystic prolactinoma (5%). Preoperative clinical features included VF deficit (41%), VF deficit plus headache (36%), or headache alone (13%). For the aggregate cohort, statistically significant reduction in mean tumor-cyst volume for the cohort was observed at all follow-up visits beyond 3 months (all P < .01). At 5-year follow-up, cyst volume reduction was sustained in 82% of cases. The mean percent reduction in tumor-cyst volume was 77.2% (SD 16.8). Ninety-one percent of patients had stable or improved vision postoperatively. The overall proportion of patients with endocrine dysfunction preoperatively (59%) and postoperatively (68%) remained stable (P > .05). Treatment failure requiring conventional surgery occurred in 3 patients who received 90Y for cyst recurrence. CONCLUSION: Stereotactic treatment of CSMs with intracavitary 90Y is associated with sustained reduction in tumor-cyst volume, improved visual function, and stable endocrine function at 5-year follow-up.