Gamma knife in the treatment of pituitary adenomas: results of a single center

Long-term hormonal and imaging outcomes of adjunctive gamma knife radiosurgery in non-functioning pituitary adenomas: a single center experience

PURPOSE

Gamma Knife Radiosurgery(GKRS) is an established modality for treatment of non-functioning pituitary adenomas(NFPA). The objective of the study was to assess long-term hormonal and imaging outcomes after adjunctive GKRS in patients with NFPA.

METHODS

A retrospective review of records of 109 patients with NFPA, from 1996 to 2020, who received adjunctive GKRS, was performed. Patients who had received GKRS as the primary modality of treatment for NFPA were not included.

RESULTS

Sixty-three (57.8%) patients were available for follow up at our institute. The median follow-up period was 47 months (range, 6-260). At a median time of 38 months (range, 8-97), 25 (39.7%) patients developed ≥ 1 new pituitary hormone deficiency. Median time to cortisol deficiency was 38 months (range, 8-55), thyroid hormone deficiency was 45.5 months (range, 12-97) and gonadotropin deficiency was 45 months (range, 21-75). The actuarial risk of developing a new pituitary hormone deficit at 1, 3, 5, 7, and 10 years was 2.5%, 11%, 26.3%, 28% and 29.7%, respectively. Adenoma size decreased in 36 (57.1%) patients, remained unchanged in 19 (30.2%) patients, and increased in 8 (12.7%) patients. Overall tumor control rate was 87.3%. Endocrinopathy-Free Survival was 47.1%, and tumor Progression-Free Survival was 93.3%, at 5 years. Five (4.6%) patients required additional treatment after GKRS. One (1.6%) patient each had worsening of headache, optic atrophy and cerebellar infarct after GKRS therapy.

CONCLUSION

GKRS offers a safe adjunctive treatment modality, with satisfactory long-term preservation of hormone functions and a high rate of tumor control, in patients with NFPA.

Gamma Knife Radiosurgery for Pituitary Tumors: A Systematic Review and Meta-Analysis

Simple Summary

Pituitary tumors represent approximately 10–15% of all brain neoplasms. Gamma Knife, the most commonly used stereotactic radiosurgery technique worldwide, plays an important role in the treatment of several pituitary neoplasm. It is currently used in cases of residual or recurrent tumors after surgery or as primary treatment when surgery is contraindicated. Its goals are long-term tumor control, preservation of visual function, and, for secreting pituitary adenomas, endocrine remission. Several retrospective case-series (level of evidence IV) on Gamma Knife for pituitary tumors have been published describing encouraging outcomes; only one systematic review and meta-analysis on non-functioning pituitary adenoma has been recently reported. We provide a systematic review of the literature and meta-analysis from the last two decades on Gamma Knife radiosurgery for several pituitary tumors with the aim of describing and confirming safety and effectiveness of this technique.

Abstract

To describe and evaluate outcomes of Gamma Knife radiosurgery (GK) for the treatment of pituitary tumors over the past twenty years, a systematic review and meta-analysis according to PRISMA statement was performed. Articles counting more than 30 patients were included. A weighted random effects models was used to calculate pooled outcome estimates. From 459 abstract reviews, 52 retrospective studies were included. Among them, 18 reported on non-functioning pituitary adenomas (NFPA), 13 on growth hormone (GH)-secreting adenomas, six on adrenocorticotropic hormone (ACTH)-secreting adenomas, four on prolactin hormone (PRL)-secreting adenomas, and 11 on craniopharyngiomas. Overall tumor control and five-year progression free survival (PFS) estimate after one GK procedure for NFPA was 93% (95% CI 89–97%) and 95% (95% CI 91–99%), respectively. In case of secreting pituitary adenomas, overall remission (cure without need for medication) estimates were 45% (95% CI 35–54%) for GH-secreting adenomas, 64% (95% CI 0.52–0.75%) for ACTH-secreting adenomas and 34% (95% CI: 19–48%) for PRL-secreting adenomas. The pooled analysis for overall tumor control and five-year PFS estimate after GK for craniopharyngioma was 74% (95% CI 67–81%) and 70% (95% CI: 64–76%), respectively. This meta-analysis confirms and quantifies safety and effectiveness of GK for pituitary tumors.

Stereotactic radiosurgery for secretory pituitary adenomas: systematic review and International Stereotactic Radiosurgery Society practice recommendations

OBJECTIVE

A systematic review was performed to provide objective evidence on the use of stereotactic radiosurgery (SRS) in the management of secretory pituitary adenomas and develop consensus recommendations.

METHODS

The authors performed a systematic review of the English-language literature up until June 2018 using the PRISMA guidelines. The PubMed (Medline), Embase, and Cochrane databases were searched. A total of 45 articles reporting single-institution outcomes of SRS for acromegaly, Cushing's disease, and prolactinomas were selected and included in the analysis.

RESULTS

For acromegaly, random effects meta-analysis estimates for crude tumor control rate, crude endocrine remission rate, and any new hypopituitarism rates were 97.0% (95% CI 96.0%-98.0%), 44.0% (95% CI 35.0%-53.0%), and 17.0% (95% CI 13.0%-23.0%), respectively. For Cushing's disease, random effects estimates for crude tumor control rate, crude endocrine remission rate, and any new hypopituitarism rate were 92.0% (95% CI 87.0%-95.0%), 48.0% (95% CI 35.0%-61.0%), and 21.0% (95% CI 13.0%-31.0%), respectively. For prolactinomas, random effects estimates for crude tumor control rate, crude endocrine remission rate, and any new hypopituitarism rate were 93.0% (95% CI 90.0%-95.0%), 28.0% (95% CI 19.0%-39.0%), and 12.0% (95% CI 6.0%-24.0%), respectively. Meta-regression analysis did not show a statistically significant association between mean margin dose with crude endocrine remission rate or mean margin dose with development of any new hypopituitarism rate for any of the secretory subtypes.

CONCLUSIONS

SRS offers effective tumor control of hormone-producing pituitary adenomas in the majority of patients but a lower rate of endocrine improvement or remission.

Efficacy and Safety of Stereotactic Radiotherapy in Cushing's Disease: A Single Center Experience

OBJECTIVE

To determine the efficacy and safety of stereotactic radiotherapy (RT) in patients with Cushing's disease (CD).

METHODS

The study included 38 patients [31 patients who received gamma knife radiosurgery (GKS) and 7 patients who received cyberknife hypofractionated RT (HFRT)] with CD. Hormonal remission was considered if the patient had suppressed cortisol levels after low dose dexamethasone, normal 24-hour urinary free cortisol (UFC), and lack or regression of clinical features.

RESULTS

Biochemical control after RT was observed in 52.6% of the patients with CD and median time to hormonal remission was 15 months. Tumor size control was obtained in all of the patients. There was no significant relationship between remission rate and laboratory, radiological and pathological variables except for preoperative UFC. Remission rate was higher in patients with lower preoperative UFC. Time to remission increased in parallel to postoperative cortisol and 1mg DST level. Although medical therapy before RT did not affect the rate of- and time to remission, medical therapy after RT prolonged the time to hormonal remission.

CONCLUSION

In this current single center experience, postoperative cortisol and 1mg DST levels were found as the determinants of time to remission. Although medical therapy before RT did not affect the rate of- and time to remission, medical therapy after RT prolonged the time to biochemical control . This latter finding might suggest a radioprotective effect of cortisol lowering medication use on peri-RT period.

Stereotactic radiosurgery for non-functioning pituitary adenomas: meta-analysis and International Stereotactic Radiosurgery Society practice opinion

BACKGROUND

This systematic review reports on outcomes and toxicities following stereotactic radiosurgery (SRS) for non-functioning pituitary adenomas (NFAs) and presents consensus opinions regarding appropriate patient management.

METHODS

Using the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses, a systematic review was performed from articles of ≥10 patients with NFAs published prior to May 2018 from the Medline database using the key words "radiosurgery" and "pituitary" and/or "adenoma." Weighted random effects models were used to calculate pooled outcome estimates.

RESULTS

Of the 678 abstracts reviewed, 35 full-text articles were included describing the outcomes of 2671 patients treated between 1971 and 2017 with either single fraction SRS or hypofractionated stereotactic radiotherapy (HSRT). All studies were retrospective (level IV evidence). SRS was used in 27 studies (median dose: 15 Gy, range: 5-35 Gy) and HSRT in 8 studies (median total dose: 21 Gy, range: 12-25 Gy, delivered in 3-5 fractions). The 5-year random effects local control estimate after SRS was 94% (95% CI: 93.0-96.0%) and 97.0% (95% CI: 93.0-98.0%) after HSRT. The 10-year local control random effects estimate after SRS was 83.0% (95% CI: 77.0-88.0%). Post-SRS hypopituitarism was the most common treatment-related toxicity observed, with a random effects estimate of 21.0% (95% CI: 15.0-27.0%), whereas visual dysfunction or other cranial nerve injuries were uncommon (range: 0-7%).

CONCLUSIONS

SRS is an effective and safe treatment for patients with NFAs. Encouraging short-term data support HSRT for select patients, and mature outcomes are needed before definitive recommendations can be made. Clinical practice opinions were developed on behalf of the International Stereotactic Radiosurgery Society (ISRS).

Multiple Pituitary Apoplexy-Cavernous Sinus Invasion as Major Risk Factor for Recurrent Hemorrhage

OBJECTIVE

Pituitary apoplexy is a rare but potentially life-threatening disorder that occurs in up to 10% of adenomas. Whereas risk factors for the initial hemorrhagic event are well described, there is minor knowledge on clinical symptomatic recurrent pituitary apoplexies.

METHODS

At the Medical University of Vienna, 76 patients were surgically treated for clinical symptomatic pituitary apoplexy between 1990 and 2017. Four patients (5.3%) suffered multiple pituitary apoplexies after initial surgery. In this retrospective study, neuroradiologic images, clinical data, and intraoperative findings were reviewed for potential risk factors of multiple apoplexies in pituitary adenomas.

RESULTS

Patients with multiple apoplexies had significantly higher Knosp grading on preoperative imaging (median grade 4), and more frequently observed cavernous sinus invasion intraoperatively (P = 0.01). Consequently, all cases with multiple pituitary apoplexies remained with residual adenoma postoperatively. In cases of residual tumor within the cavernous sinus, recurrent apoplexy occurred in 23.5% of patients. A tumor recurrence/residual was resected significantly earlier in patients with single apoplexy (median 2.2 years) than in patients with multiple apoplexies (median 5.4 years; P = 0.05). Multiple pituitary apoplexies caused significantly greater rates of ophthalmoplegia (75% vs. 14.1%; P = 0.01) and long-term hormone-replacement therapy was necessary in all cases.

CONCLUSIONS

Cavernous sinus invasion and subtotal resection are high risk factors for multiple apoplexies in pituitary adenomas. Early treatment is recommended for residual tumor in the cavernous sinus to minimize the risk of recurrent apoplexy with subsequent worse clinical outcome.

Single- and Multi-Fraction Stereotactic Radiosurgery Dose Tolerances of the Optic Pathways

PURPOSE

Dosimetric and clinical predictors of radiation-induced optic nerve/chiasm neuropathy (RION) after single-fraction stereotactic radiosurgery (SRS) or hypofractionated (2-5 fractions) radiosurgery (fSRS) were analyzed from pooled data that were extracted from published reports (PubMed indexed from 1990 to June 2015). This study was undertaken as part of the American Association of Physicists in Medicine Working Group on Stereotactic Body Radiotherapy, investigating normal tissue complication probability (NTCP) after hypofractionated radiation.

METHODS AND MATERIALS

Eligible studies described dose delivered to optic nerve/chiasm and provided crude or actuarial toxicity risks, with visual endpoints (ie, loss of visual acuity, alterations in visual fields, and/or blindness/complete vision loss). Studies of patients with optic nerve sheath tumors, optic nerve gliomas, or ocular/uveal melanoma were excluded to obviate direct tumor effects on visual outcomes, as were studies not specifying causes of vision loss (ie, tumor progression vs RION).

RESULTS

Thirty-four studies (1578 patients) were analyzed. Histologies included pituitary adenoma, cavernous sinus meningioma, craniopharyngioma, and malignant skull base tumors. Prior resection (76% of patients) did not correlate with RION risk (P = .66). Prior irradiation (6% of patients) was associated with a crude 10-fold increased RION risk versus no prior radiation therapy. In patients with no prior radiation therapy receiving SRS/fSRS in 1-5 fractions, optic apparatus maximum point doses resulting in <1% RION risks include 12 Gy in 1 fraction (which is greater than our recommendation of 10 Gy in 1 fraction), 20 Gy in 3 fractions, and 25 Gy in 5 fractions. Omitting multi-fraction data (and thereby eliminating uncertainties associated with dose conversions), a single-fraction dose of 10 Gy was associated with a 1% RION risk. Insufficient details precluded modeling of NTCP risks after prior radiation therapy.

CONCLUSIONS

Optic apparatus NTCP and tolerance doses after single- and multi-fraction stereotactic radiosurgery are presented. Additional standardized dosimetric and toxicity reporting is needed to facilitate future pooled analyses and better define RION NTCP after SRS/fSRS.

Target delineation and optimal radiosurgical dose for pituitary tumors

Stereotactic radiosurgery (SRS) delivered as either single-fraction or multi-fraction SRS (2–5 fractions) is frequently employed in patients with residual or recurrent pituitary adenoma. The most common delivery systems used for SRS include the cobalt-60 system Gamma Knife, the CyberKnife (CK) robotic radiosurgery system, or a modified conventional radiotherapy machine (linear accelerator, LINAC). Tumor control and normalization of hormone hypersecretion have been reported in 75–100 % and 25–80 % of patients, respectively. Hypopituitarism is the most commonly reported late complication of radiation treatment, whereas other toxicities occur less frequently. We have provided an overview of the recent available literature on SRS in patients with a pituitary adenoma. Critical aspects of pituitary irradiation, including target delineation and doses to organs at risk, optimal radiation dose, as well as the long-term efficacy and toxicity of SRS for either nonfunctioning or secreting pituitary adenomas are discussed. Single-fraction SRS represents an effective treatment for patients with a pituitary adenoma; however, caution should be used for lesions > 2.5–3 cm in size and/or involving the anterior optic pathway. Future studies will be necessary to optimize target doses and critical organ dose constrains in order to reduce the long-term toxicity of treatments while maintaining high efficacy.

Delayed cerebrospinal fluid rhinorrhea four years after gamma knife surgery for juvenile angiofibroma

Juvenile angiofibroma (JA) is a highly vascularized tumor that often recurs or regrows. Recently, gamma knife surgery (GKS) was attempted on unresectable or remnant JA. We experienced a JA case that developed cerebrospinal fluid (CSF) rhinorrhea 4 years after GKS. Two surgical excisions using midfacial degloving approach were performed before GKS. After radiosurgery, the tumor was controlled, and no early complications were observed. However, 4 years after, intractable CSF leakage developed as a late complication, and we thus performed 4 subsequent endoscopic surgical repairs. The CSF leakage is very rare but can occur as a late complication of GKS and should be treated aggressively.

The Treatment of Cushing's Disease

Cushing's disease (CD), or pituitary-dependent Cushing's syndrome, is a severe endocrine disease caused by a corticotroph pituitary tumor and associated with increased morbidity and mortality. The first-line treatment for CD is pituitary surgery, which is followed by disease remission in around 78% and relapse in around 13% of patients during the 10-year period after surgery, so that nearly one third of patients experience in the long-term a failure of surgery and require an additional second-line treatment. Patients with persistent or recurrent CD require additional treatments, including pituitary radiotherapy, adrenal surgery, and/or medical therapy. Pituitary radiotherapy is effective in controlling cortisol excess in a large percentage of patients, but it is associated with a considerable risk of hypopituitarism. Adrenal surgery is followed by a rapid and definitive control of cortisol excess in nearly all patients, but it induces adrenal insufficiency. Medical therapy has recently acquired a more important role compared to the past, due to the recent employment of novel compounds able to control cortisol secretion or action. Currently, medical therapy is used as a presurgical treatment, particularly for severe disease; or as postsurgical treatment, in cases of failure or incomplete surgical tumor resection; or as bridging therapy before, during, and after radiotherapy while waiting for disease control; or, in selected cases, as primary therapy, mainly when surgery is not an option. The adrenal-directed drug ketoconazole is the most commonly used drug, mainly because of its rapid action, whereas the glucocorticoid receptor antagonist, mifepristone, is highly effective in controlling clinical comorbidities, mainly glucose intolerance, thus being a useful treatment for CD when it is associated with diabetes mellitus. Pituitary-directed drugs have the advantage of acting at the site responsible for CD, the pituitary tumor. Among this group of drugs, the dopamine agonist cabergoline and the somatostatin analog pasireotide result in disease remission in a consistent subgroup of patients with CD. Recently, pasireotide has been approved for the treatment of CD when surgery has failed or when surgery is not an option, and mifepristone has been approved for the treatment of Cushing's syndrome when associated with impairment of glucose metabolism in case of the lack of a surgical indication. Recent experience suggests that the combination of different drugs may be able to control cortisol excess in a great majority of patients with CD.

Stereotactic radiotherapy and radiosurgery for non-functioning and secreting pituitary adenomas

Radiotherapy (RT) is frequently employed in patients with residual or recurrent pituitary adenoma with excellent rates of tumor control and remission of hormonal hypersecretion. Advances in RT have improved with the use of stereotactic techniques either as fractionated stereotactic radiotherapy (FSRT) or stereotactic radiosurgery (SRS), all aiming to improve the dose distribution to the tumor while reducing the amount of normal brain receiving significant doses of radiation. We provide an overview of the recent published literature on the long-term efficacy and adverse effects of stereotactic irradiation in nonfunctioning and secreting pituitary adenomas. Both techniques are associated with excellent clinical outcomes; however, advantages and drawbacks of each of these techniques in terms of local control, hormonal excess normalization, and radiation-induced toxicity remain a matter of debate. In clinical practice, single-fraction SRS may represent a convenient approach to patients with small and medium-sized pituitary adenoma away at least 2 mm from the optic chiasm, whereas FSRT is preferred over SRS for lesions >2.5-3 cm in size and/or involving the anterior optic pathway.