A Retrospective Review of the Clinical Outcomes of Stereotactic Radiation for Pituitary Adenoma In Ramathibodi Hospital

Abstract

Background: Stereotactic radiation, including conventional stereotactic radiotherapy (CSRT), hypofractionated stereotactic radiotherapy (HFSRT), and stereotactic radiosurgery (SRS), plays a crucial role in the management of nonfunctioning pituitary adenomas (NFPAs) and functioning. However, the optimal selection of treatment modality to maximize long-term control while minimizing late toxicities, particularly delayed hypopituitarism, remains a subject of ongoing clinical debate. Objective: To evaluate the long-term efficacy and safety of a tailored, risk-adapted stereotactic radiation strategy for the management of pituitary adenomas. Material and method: We retrospectively reviewed 127 patients with pituitary adenomas treated with conventional stereotactic radiotherapy (CSRT) (n=86), hypofractionated stereotactic radiotherapy (HFSRT) (n=29), or stereotactic radiosurgery (SRS) (n=12). The primary outcomes were radiographic tumor local control and biochemical control in functioning adenomas. Secondary outcomes included late toxicities and the evaluation of predictors for new-onset hypopituitarism, which was specifically analyzed using Cox proportional hazards regression in a subgroup of preoperatively hormonally intact patients (n=73). Results: The overall radiographic tumor control rate was 96.6%, with no significant difference in progression-free survival (PFS) across the three modalities (p = 0.823). Among functioning adenomas, the overall biochemical control rate was 87.9%, with 69.7% achieving remission off medication. Regarding secondary outcomes, the treatment demonstrated a highly favorable safety profile; zero instances of Grade 3-4 severe toxicities, radiation necrosis, or cerebrovascular events were observed. New-onset hypopituitarism occurred in 12.6% of the cohort (all Grade 1-2). In the preoperatively hormonally intact subgroup, multivariate analysis revealed that the specific radiation modality was not an independent predictor of new endocrine deficits. Conclusion: A tailored, risk-adapted stereotactic radiation strategy provides excellent and comparable long-term local control and biochemical control for pituitary adenomas. The choice of radiation modality does not independently predict delayed hypopituitarism. Instead, the risk of endocrine decline is likely multifactorial, emphasizing the importance of baseline tumor complexity and the preexisting functional reserve of the gland when counseling patients.