Dose to neuroanatomical structures surrounding pituitary adenomas and the effect of stereotactic radiosurgery on neuroendocrine function: an international multicenter study

Long-Term Outcomes After Cyberknife Radiosurgery for Nonfunctioning Pituitary Adenomas

BACKGROUND AND OBJECTIVES

Stereotactic radiosurgery (SRS) has been widely adopted as an important adjunctive treatment modality for managing nonfunctioning pituitary adenomas (NFPAs). However, current studies on the long-term effects of SRS on pituitary adenomas have been largely limited by small sample sizes and short follow-up periods. The aim of this study was to evaluate the long-term outcomes of SRS for NFPAs.

METHODS

We conducted a retrospective review of 178 patients with NFPAs who received Cyberknife radiosurgery at a single institution between February 2008 and July 2021. Long-term outcomes of tumor control, new-onset hypopituitarism, and new visual disorders were assessed.

RESULTS

During a median radiological follow-up of 49.7 months (range, 2.5-158.1 months), only 11 (7.0%) patients experienced tumor progression. The progression-free survival at 3, 5, and 10 years was 97.47%, 95.57%, and 93.04%, respectively. New-onset hypopituitarism was diagnosed in 27 (16.9%) patients with a median clinical follow-up duration of 71.2 months (range, 11.5-175.4 months). The median time from SRS to new-onset hypopituitarism was 28.3 months (range, 2.8-101.7 months). The cumulative incidence of new-onset hypopituitarism at 3, 5, and 10 years was 8.47%, 12.43%, and 15.25%, respectively. Biological effective dose >140 Gy and single fraction equivalent dose >16.0 Gy were significant risk factors for new-onset hypopituitarism (P = .046). Other adverse events were experienced by 15 (8.4%) patients, 9 (5.1%) of whom presented with new visual disorders. Development of new visual disorders was associated with a pretreatment tumor volume of >2.5 mL (P = .044).

CONCLUSION

SRS is an effective and relatively safe means of managing both primary and residual/recurrent NFPAs.

Stereotactic radiosurgery for nonfunctioning pituitary tumor: A multicenter study of new pituitary hormone deficiency

BACKGROUND

Stereotactic radiosurgery (SRS) is used to treat recurrent or residual nonfunctioning pituitary neuroendocrine tumors (NFPA). The objective of the study was to assess imaging and development of new pituitary hormone deficiency.

METHODS

Patients treated with single-session SRS for a NFPA were included in this retrospective, multicenter study. Tumor control and new pituitary dysfunction were evaluated using Cox analysis and Kaplan-Meier curves.

RESULTS

A total of 869 patients (male 476 [54.8%], median age at SRS 52.5 years [Interquartile range (IQR): 18.9]) were treated using a median margin dose of 14Gy (IQR: 4) for a median tumor volume of 3.4 cc (IQR: 4.3). With a median radiological follow-up of 3.7 years (IQR: 4.8), volumetric tumor reduction occurred in 451 patients (51.9%), stability in 364 (41.9%) and 54 patients (6.2%) showed tumor progression.The probability of tumor control was 95.5% (95% Confidence Interval [CI]: 93.8-97.3) and 88.8% (95%CI: 85.2-92.5) at 5 and 10 years, respectively. A margin dose >14 Gy was associated with tumor control (Hazard Ratio [HR]:0.33, 95% CI: 0.18-0.60, P < 0.001). The probability of new hypopituitarism was 9.9% (95% CI: 7.3-12.5) and 15.3% (95% CI: 11-19.4) at 5 and 10 years, respectively. A maximum point dose >10 Gy in the pituitary stalk was associated with new pituitary hormone deficiency (HR: 3.47, 95% CI: 1.95-6.19). The cumulative probability of new cortisol, thyroid, gonadotroph, and growth hormone deficiency was 8% (95% CI: 3.9-11.9), 8.3% (95% CI: 3.9-12.5), 3.5% (95% CI: 1.7-5.2), and 4.7% (95% CI: 1.9-7.4), respectively at 10 years.

CONCLUSIONS

SRS provides long-term tumor control with a 15.3% risk of hypopituitarism at 10 years.

Iatrogenic adrenal insufficiency in adults

Iatrogenic adrenal insufficiency (IAI) is the most common form of adrenal insufficiency in adult patients, although its overall exact prevalence remains unclear. IAI is associated with adverse clinical outcomes, including adrenal crisis, impaired quality of life and increased mortality; therefore, it is imperative that clinicians maintain a high index of suspicion in patients at risk of IAI to facilitate timely diagnosis and appropriate management. Herein, we review the major causes, clinical consequences, diagnosis and care of patients with IAI. The management of IAI, particularly glucocorticoid-induced (or tertiary) adrenal insufficiency, can be particularly challenging, and the provision of adequate glucocorticoid replacement must be balanced against minimizing the cardiometabolic effects of excess glucocorticoid exposure and optimizing recovery of the hypothalamic-pituitary-adrenal axis. We review current treatment strategies and their limitations and discuss developments in optimizing treatment of IAI. This comprehensive Review aims to aid clinicians in identifying who is at risk of IAI, how to approach screening of at-risk populations and how to treat patients with IAI, with a focus on emergency management and prevention of an adrenal crisis.

Adjuvant versus on-progression Gamma Knife radiosurgery for residual nonfunctioning pituitary adenomas: a matched-cohort analysis

OBJECTIVE

Radiological progression occurs in 50%-60% of residual nonfunctioning pituitary adenomas (NFPAs). Stereotactic radiosurgery (SRS) is a safe and effective management option for residual NFPAs, but there is no consensus on its optimal timing. This study aims to define the optimal timing of SRS for residual NFPAs.

METHODS

This retrospective, multicenter study involved 375 patients with residual NFPAs managed with SRS. The patients were divided into adjuvant (ADJ; treated for stable residual NFPA within 6 months of resection) and progression (PRG) cohorts (treated for residual NFPA progression). Factors associated with tumor progression and clinical deterioration were analyzed.

RESULTS

Following propensity-score matching, each cohort consisted of 130 patients. At last follow-up, tumor control was achieved in 93.1% of patients in the ADJ cohort and in 96.2% of patients in the PRG cohort (HR 1.6, 95% CI 0.55-4.9, p = 0.37). Hypopituitarism was associated with a maximum point dose of > 8 Gy to the pituitary stalk (HR 4.5, 95% CI 1.6-12.6, p = 0.004). No statistically significant difference was noted in crude new-onset hypopituitarism rates (risk difference [RD] = -0.8%, p > 0.99) or visual deficits (RD = -2.3%, p = 0.21) between the two cohorts at the last follow-up. The median time from resection to new hypopituitarism was longer in the PRG cohort (58.9 vs 29.7 months, p = 0.01).

CONCLUSIONS

SRS at residual NFPA progression does not appear to alter the probability of tumor control or hormonal/visual deficits compared with adjuvant SRS. Deferral of radiosurgical management to the time of radiological progression could significantly prolong the time to radiosurgically induced pituitary dysfunction. A lower maximum point dose (< 8 Gy) to the pituitary stalk portended a more favorable chance of preserving pituitary function after SRS.

Role of radiosurgery in the treatment of Cushing's disease

Radiotherapy is a useful adjuvant treatment for patients with Cushing's disease that is not cured by surgery. In particular, Gamma Knife radiosurgery (GKRS) has been increasingly used worldwide as the preferred radiation technique in patients with persistent or recurrent Cushing's disease. The most widely accepted criterion for hormonal remission after GKRS is normalization of urinary free cortisol (UFC) levels. When a clear biological target is not identified, irradiation of the whole pituitary gland can be considered. The 5-year probability of remission is 65%-75%. Normalization of hypercortisolism usually occurs within 3 years from GKRS treatment and control of tumor growth is optimal, approaching more than 90%. No clear predictor of a favorable outcome has emerged up to now, except for the experience of the treating team. In the largest series, development of partial or complete hypopituitarism occurred between 15% and 36%. Severe side effects of GKRS, such as optic neuropathy and oculomotor palsy, are uncommon but have been documented in patients previously exposed to radiation. Recurrence of disease has been reported in as high as 16%-18% of the patients who achieved normalization of UFC levels in the two largest series, whereas smaller series did not describe late failure of GKRS. The reason for this discrepancy is unclear, as is the relationship between hormonal and tumoral recurrence. Another unresolved issue is whether treatment with adrenal blocking drugs can jeopardize the results of GKRS. GKRS is an effective second-line treatment in patients with Cushing's disease not cured by surgery. Hypopituitarism is the most frequent side effect of GKRS, whereas severe neurologic complications are uncommon in radiation-naïve patients.

Endocrine disorders after primary gamma knife radiosurgery for pituitary adenomas: A systematic review and meta-analysis

PURPOSE

Gamma Knife radiosurgery (GKRS) is feasible for pituitary adenomas, but post-surgery GKRS may cause severe hormone deficits. We reviewed the literature on primary GKRS for pituitary adenoma focusing on radiation-induced hormone deficiencies.

METHODS

PubMed, Web-of-Science, Scopus, and Cochrane were searched upon the PRISMA guidelines to include studies describing primary GKRS for pituitary adenomas. Pooled-rates of GKRS-induced hormone deficiencies and clinical-radiological responses were analyzed with a random-effect model meta-analysis.

RESULTS

We included 24 studies comprising 1381 patients. Prolactinomas were the most common (34.2%), and 289 patients had non-functioning adenomas (20.9%). Median tumor volume was 1.6cm³ (range, 0.01-31.3), with suprasellar extension and cavernous sinus invasion detected in 26% and 31.1% cases. GKRS was delivered with median marginal dose 22.6 Gy (range, 6-49), maximum dose 50 Gy (range, 25-90), and isodose line 50% (range, 9-100%). Median maximum point doses were 9 Gy (range, 0.5-25) to the pituitary stalk, 7 Gy (range, 1-38) to the optic apparatus, and 5 Gy (range, 0.4-12.3) to the optic chiasm. Pooled 5 year rates of endocrine normalization and local tumor control were 48% (95%CI 45-51%) and 97% (95%CI 95-98%). 158 patients (11.4%) experienced endocrinopathies at a median of 45 months (range, 4-187.3) after GKRS, with pooled 5-year rates of 8% (95%CI 6-9%). GKRS-induced hormone deficiencies comprised secondary hypothyroidism (42.4%) and hypogonadotropic hypogonadism (33.5%), with panhypopituitarism reported in 31 cases (19.6%).

CONCLUSION

Primary GKRS for pituitary adenoma may correlate with lower rates of radiation-induced hypopituitarism (11.4%) than post-surgery GKRS (18-32%). Minimal doses to normal pituitary structures and long-term endocrine follow-up are of primary importance.