Outcomes following CyberKnife robotic radiosurgery for pituitary adenomas-a large single-centre study

Abstract

Introduction: The role of stereotactic radiosurgery (SRS) in pituitary adenomas (PAs) is evolving especially considering its safety. Existing literature is hampered by limited sample sizes and short-term follow-ups, impeding its preeminence in the clinical and radiological outcomes. We propose a comprehensive, single-centred study to evaluate the outcomes following CyberKnife stereotactic radiosurgery (CK SRS) for PAs in a larger patient population, incorporating meticulous clinical and radiological follow-up.

Methods: This is a retrospective cohort study of 278 cases of PAs that underwent CK SRS from 2013 to 2021. Based on their endocrinology profile, they were classified as functional adenomas (FA) and non-functional adenomas (NFA). We assessed pre and post-CK SRS clinical, visual, hormonal and radiological parameters and the associated toxicity. Where applicable, data were compared using the Independent t-test, chi-square test, Fisher Exact and Mann-Whitney U test. A p-value <0.05 was considered significant.

Results: The median age of the patients was 40.13 ± 12.61 years (111 female and 167 male patients). The median prescribed radiosurgery dose was 25.0 ± 5.0 Gy into 3 or 5 fractions. The median follow-up time was 12 months (IQR 20). Data were grouped into NFA (169, 60.8%) and FA (109, 39.2%). After adjusting for patients lost to follow-up, post-CK SRS visual perimetry improved in 80.4% of patients and tumour size reduced in 78.6% of the study population. Seventeen patients with NFA and nine with FA manifested new-onset hormonal deficiencies. No statistically significant differences were seen in post-CK SRS visual outcomes and hormone deficiency groups.

Conclusion: CK SRS is effective and safe for managing PAs, achieving tumour control and preserving visual function with minimal toxicity. Extended follow-up is needed to evaluate post-SRS toxicity and hypopituitarism.

Keywords: Cushing’s disease; CyberKnife; acromegaly; nonfunctional adenomas; pituitary adenomas; radiosurgery.

Figure 1.. Types of PAs.

Figure 2.. Sub-groups of FA.

Figure 3.. (a): A case of large pituitary macroadenoma before receiving CyberKnife radiosurgery. (b): Near complete resolution of pituitary macroadenoma of the same patient after receiving CyberKnife radiosurgery in the follow-up period.