OR2804 Endocrine And Vision Outcomes Following 90Yttrium Therapy For Cystic Sellar Lesions—A Prospective Cohort Study

Abstract Disclosure: M.A. MacLean: None. S. Ahmad: None. A.L. Hebb: None. A. Tahir: None. R. Greene: None. D.B. Clarke: None. S.A. Imran: None. Background: Untreated cystic sellar lesions can cause vision loss, endocrine dysfunction, and obstructive hydrocephalus related to growth and mass effect. Microsurgical resection, stereotactic aspiration, and radiation treatment strategies are limited by significant complications and high risk of recurrence. Stereotactic intracavitary irradiation with the beta-emitting isotope 90Yttrium (90Yt) has been proposed as an alternative to mitigate these challenges. Long term-efficacy data is lacking. Here, our objective was to prospectively assess the effect of 90Yt on cyst volume, endocrine, and vision outcomes. Methods: We conducted a Health Canada approved, single-centre, prospective cohort study. Clinical outcome measures included cyst volume measured on magnetic resonance imaging, formal visual field (VF) testing, and hypothalamic-pituitary (HP) hormonal function. All patients provided informed consent and underwent right frontal stereotactic insertion of 90Yt colloid (200 Gy cyst wall). Results: Twenty-two patients (55% females) received 90Yt therapy. Mean age was 63.5 (SD 15.4) years with no difference between genders (p = 0.055). Mean duration of follow-up was 52 months (range 5-113). Cystic lesions included: craniopharyngioma (86%), Rathke’s cleft cyst (9%) and cystic prolactinoma (5%). Mean tumor cyst volumes were reduced by 77% at 12-month follow-up (pre-operative: 5.2, SD 4.5 cc; 12 months post-operative: 1.2, SD 1.5 cc; p = 0.002). Males had larger tumor volumes at baseline (7.7, SD 5.0 cc vs. 3.2, SD 2.8; p = 0.02) and 3 months (4.7, SD 3.4 vs. 1.8, SD 2.0; p = 0.04) but these differences had resolved by 9-month follow-up. Pre-operative clinical features included: VF deficit (36%), VF deficit plus headache (36%), headache alone (9%), hydrocephalus (5%), and 14% were asymptomatic. HP hormone dysfunction was observed in 59% of patients pre-operatively (27% complete; 73% partial) and 68% post-operatively (p = 0.50); specifically, no differences were found pre- and post-operatively for secondary hypogonadism (50% vs. 55%), hypothyroidism (45% vs. 59%), hypoadrenalism (36% vs. 27%), growth hormone deficiency (27% vs. 23%), diabetes insipidus (23% vs. 27%), and hyperprolactinemia (36% vs. 36%) (all p > 0.05). Pre-operative VF deficits were found in 68% of patients, of which 32% normalized and 36% remained stable (p = 0.180). Worsened vision was detected in 9% of patients post-operatively. Treatment failure requiring conventional surgery occurred in 18% of patients. Conclusions:90Yt therapy significantly reduced tumor cyst size and stabilized both endocrine function and vision in patients with cystic lesions of the sellar region. Presentation: Sunday, June 18, 2023