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I. Jonathan Pomeraniec, Zhiyuan Xu, Cheng-Chia Lee, Huai-Che Yang, Tomas Chytka, Roman Liscak, Roberto Martinez-Alvarez, Nuria Martinez-Moreno, Luca Attuati, Piero Picozzi, Douglas Kondziolka, Monica Mureb, Kenneth Bernstein, David Mathieu, Michel Maillet, Akiyoshi Ogino, Hao Long, Hideyuki Kano, L. Dade Lunsford, Brad E. Zacharia, Christine Mau, Leonard C. Tuanquin, Christopher Cifarelli, David Arsanious, Joshua Hack, Ronald E. Warnick, Ben A. Strickland, Gabriel Zada, Eric L. Chang, Herwin Speckter, Samir Patel, Dale Ding, Darrah Sheehan, Kimball Sheehan, Svetlana Kvint, Love Y. Buch, Alexander R. Haber, Jacob Shteinhart, Mary Lee Vance, and Jason P. Sheehan

OBJECTIVE

Stereotactic radiosurgery (SRS) provides a safe and effective therapeutic modality for patients with pituitary adenomas. The mechanism of delayed endocrine deficits based on targeted radiation to the hypothalamic-pituitary axis remains unclear. Radiation to normal neuroendocrine structures likely plays a role in delayed hypopituitarism after SRS. In this multicenter study by the International Radiosurgery Research Foundation (IRRF), the authors aimed to evaluate radiation tolerance of structures surrounding pituitary adenomas and identify predictors of delayed hypopituitarism after SRS for these tumors.

METHODS

This is a retrospective review of patients with pituitary adenomas who underwent single-fraction SRS from 1997 to 2019 at 16 institutions within the IRRF. Dosimetric point measurements of 14 predefined neuroanatomical structures along the hypothalamus, pituitary stalk, and normal pituitary gland were made. Statistical analyses were performed to determine the impact of doses to critical structures on clinical, radiographic, and endocrine outcomes.

RESULTS

The study cohort comprised 521 pituitary adenomas treated with SRS. Tumor control was achieved in 93.9% of patients over a median follow-up period of 60.1 months, and 22.5% of patients developed new loss of pituitary function with a median treatment volume of 3.2 cm3. Median maximal radiosurgical doses to the hypothalamus, pituitary stalk, and normal pituitary gland were 1.4, 7.2, and 11.3 Gy, respectively. Nonfunctioning adenoma status, younger age, higher margin dose, and higher doses to the pituitary stalk and normal pituitary gland were independent predictors of new or worsening hypopituitarism. Neither the dose to the hypothalamus nor the ratio between doses to the pituitary stalk and gland were significant predictors. The threshold of the median dose to the pituitary stalk for new endocrinopathy was 10.7 Gy in a single fraction (OR 1.77, 95% CI 1.17–2.68, p = 0.006).

CONCLUSIONS

SRS for the treatment of pituitary adenomas affords a high tumor control rate with an acceptable risk of new or worsening endocrinopathy. This evaluation of point dosimetry to adjacent neuroanatomical structures revealed that doses to the pituitary stalk, with a threshold of 10.7 Gy, and doses to the normal gland significantly increased the risk of post-SRS hypopituitarism. In patients with preserved pre-SRS neuroendocrine function, limiting the dose to the pituitary stalk and gland while still delivering an optimal dose to the tumor appears prudent.

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Nasser Mohammed, Yi-Chieh Hung, Zhiyuan Xu, Tomas Chytka, Roman Liscak, Manjul Tripathi, David Arsanious, Christopher P. Cifarelli, Marco Perez Caceres, David Mathieu, Herwin Speckter, Gautam U. Mehta, Gregory P. Lekovic, and Jason P. Sheehan

OBJECTIVE

The management of neurofibromatosis type 2 (NF2)–associated meningiomas is challenging. The role of Gamma Knife radiosurgery (GKRS) in the treatment of these tumors remains to be fully defined. In this study, the authors aimed to examine the role of GKRS in the treatment of NF2-associated meningiomas and to evaluate the outcomes and complications after treatment.

METHODS

Seven international medical centers contributed data for this retrospective cohort. Tumor progression was defined as a ≥ 20% increase from the baseline value. The clinical features, treatment details, outcomes, and complications were studied. The median follow-up was 8.5 years (range 0.6–25.5 years) from the time of initial GKRS. Shared frailty Cox regression was used for analysis.

RESULTS

A total of 204 meningiomas in 39 patients treated with GKRS were analyzed. Cox regression analysis showed that increasing the maximum dose (p = 0.02; HR 12.2, 95% CI 1.287–116.7) and a lower number of meningiomas at presentation (p = 0.03; HR 0.9, 95% CI 0.821–0.990) were predictive of better tumor control in both univariable and multivariable settings. Age at onset, sex, margin dose, location, and presence of neurological deficit were not predictive of tumor progression. The cumulative 10-year progression-free survival was 94.8%. Radiation-induced adverse effects were noted in 4 patients (10%); these were transient and managed medically. No post-GKRS malignant transformation was noted in 287 person-years of follow-up.

CONCLUSIONS

GKRS achieved effective tumor control with a low and generally acceptable rate of complications in NF2-associated meningiomas. There did not appear to be an appreciable risk of post–GKRS-induced malignancy in patients with NF2-treated meningiomas.

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Yi-Chieh Hung, Cheng-Chia Lee, Huai-che Yang, Nasser Mohammed, Kathryn N. Kearns, Shi-Bin Sun, David Mathieu, Charles J. Touchette, Ahmet F. Atik, Inga S. Grills, Bryan Squires, Dale Ding, Brian J. Williams, Mehran B. Yusuf, Shiao Y. Woo, Roman Liscak, Jaromir Hanuska, Jay C. Shiao, Douglas Kondziolka, L. Dade Lunsford, Zhiyuan Xu, and Jason P. Sheehan

OBJECTIVE

Central neurocytomas (CNs) are uncommon intraventricular tumors, and their rarity renders the risk-to-benefit profile of stereotactic radiosurgery (SRS) unknown. The aim of this multicenter, retrospective cohort study was to evaluate the outcomes of SRS for CNs and identify predictive factors.

METHODS

The authors retrospectively analyzed a cohort of patients with CNs treated with SRS at 10 centers between 1994 and 2018. Tumor recurrences were classified as local or distant. Adverse radiation effects (AREs) and the need for a CSF shunt were also evaluated.

RESULTS

The study cohort comprised 60 patients (median age 30 years), 92% of whom had undergone prior resection or biopsy and 8% received their diagnosis based on imaging alone. The median tumor volume and margin dose were 5.9 cm3 and 13 Gy, respectively. After a median clinical follow-up of 61 months, post-SRS tumor recurrence occurred in 8 patients (13%). The 5- and 10-year local tumor control rates were 93% and 87%, respectively. The 5- and 10-year progression-free survival rates were 89% and 80%, respectively. AREs were observed in 4 patients (7%), but only 1 was symptomatic (2%). Two patients underwent post-SRS tumor resection (3%). Prior radiotherapy was a predictor of distant tumor recurrence (p = 0.044). Larger tumor volume was associated with pre-SRS shunt surgery (p = 0.022).

CONCLUSIONS

Treatment of appropriately selected CNs with SRS achieves good tumor control rates with a reasonable complication profile. Distant tumor recurrence and dissemination were observed in a small proportion of patients, which underscores the importance of close post-SRS surveillance of CN patients. Patients with larger CNs are more likely to require shunt surgery before SRS.

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Yi-Chieh Hung, Cheng-Chia Lee, Huai-che Yang, Nasser Mohammed, Kathryn N. Kearns, Shi-Bin Sun, David Mathieu, Charles J. Touchette, Ahmet F. Atik, Inga S. Grills, Bryan Squires, Dale Ding, Brian J. Williams, Mehran B. Yusuf, Shiao Y. Woo, Roman Liscak, Jaromir Hanuska, Jay C. Shiao, Douglas Kondziolka, L. Dade Lunsford, Zhiyuan Xu, and Jason P. Sheehan

OBJECTIVE

Central neurocytomas (CNs) are uncommon intraventricular tumors, and their rarity renders the risk-to-benefit profile of stereotactic radiosurgery (SRS) unknown. The aim of this multicenter, retrospective cohort study was to evaluate the outcomes of SRS for CNs and identify predictive factors.

METHODS

The authors retrospectively analyzed a cohort of patients with CNs treated with SRS at 10 centers between 1994 and 2018. Tumor recurrences were classified as local or distant. Adverse radiation effects (AREs) and the need for a CSF shunt were also evaluated.

RESULTS

The study cohort comprised 60 patients (median age 30 years), 92% of whom had undergone prior resection or biopsy and 8% received their diagnosis based on imaging alone. The median tumor volume and margin dose were 5.9 cm3 and 13 Gy, respectively. After a median clinical follow-up of 61 months, post-SRS tumor recurrence occurred in 8 patients (13%). The 5- and 10-year local tumor control rates were 93% and 87%, respectively. The 5- and 10-year progression-free survival rates were 89% and 80%, respectively. AREs were observed in 4 patients (7%), but only 1 was symptomatic (2%). Two patients underwent post-SRS tumor resection (3%). Prior radiotherapy was a predictor of distant tumor recurrence (p = 0.044). Larger tumor volume was associated with pre-SRS shunt surgery (p = 0.022).

CONCLUSIONS

Treatment of appropriately selected CNs with SRS achieves good tumor control rates with a reasonable complication profile. Distant tumor recurrence and dissemination were observed in a small proportion of patients, which underscores the importance of close post-SRS surveillance of CN patients. Patients with larger CNs are more likely to require shunt surgery before SRS.

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Diogo Cordeiro, Zhiyuan Xu, Gautam U. Mehta, Dale Ding, Mary Lee Vance, Hideyuki Kano, Nathaniel Sisterson, Huai-che Yang, Douglas Kondziolka, L. Dade Lunsford, David Mathieu, Gene H. Barnett, Veronica Chiang, John Lee, Penny Sneed, Yan-Hua Su, Cheng-chia Lee, Michal Krsek, Roman Liscak, Ahmed M. Nabeel, Amr El-Shehaby, Khaled Abdel Karim, Wael A. Reda, Nuria Martinez-Moreno, Roberto Martinez-Alvarez, Kevin Blas, Inga Grills, Kuei C. Lee, Mikulas Kosak, Christopher P. Cifarelli, Gennadiy A. Katsevman, and Jason P. Sheehan

OBJECTIVE

Recurrent or residual adenomas are frequently treated with Gamma Knife radiosurgery (GKRS). The most common complication after GKRS for pituitary adenomas is hypopituitarism. In the current study, the authors detail the timing and types of hypopituitarism in a multicenter, international cohort of pituitary adenoma patients treated with GKRS.

METHODS

Seventeen institutions pooled clinical data obtained from pituitary adenoma patients who were treated with GKRS from 1988 to 2016. Patients who had undergone prior radiotherapy were excluded. A total of 1023 patients met the study inclusion criteria. The treated lesions included 410 nonfunctioning pituitary adenomas (NFPAs), 262 cases of Cushing’s disease (CD), and 251 cases of acromegaly. The median follow-up was 51 months (range 6–246 months). Statistical analysis was performed using a Cox proportional hazards model to evaluate factors associated with the development of new-onset hypopituitarism.

RESULTS

At last follow-up, 248 patients had developed new pituitary hormone deficiency (86 with NFPA, 66 with CD, and 96 with acromegaly). Among these patients, 150 (60.5%) had single and 98 (39.5%) had multiple hormone deficiencies. New hormonal changes included 82 cortisol (21.6%), 135 thyrotropin (35.6%), 92 gonadotropin (24.3%), 59 growth hormone (15.6%), and 11 vasopressin (2.9%) deficiencies. The actuarial 1-year, 3-year, 5-year, 7-year, and 10-year rates of hypopituitarism were 7.8%, 16.2%, 22.4%, 27.5%, and 31.3%, respectively. The median time to hypopituitarism onset was 39 months.

In univariate analyses, an increased rate of new-onset hypopituitarism was significantly associated with a lower isodose line (p = 0.006, HR = 8.695), whole sellar targeting (p = 0.033, HR = 1.452), and treatment of a functional pituitary adenoma as compared with an NFPA (p = 0.008, HR = 1.510). In multivariate analyses, only a lower isodose line was found to be an independent predictor of new-onset hypopituitarism (p = 0.001, HR = 1.38).

CONCLUSIONS

Hypopituitarism remains the most common unintended effect of GKRS for a pituitary adenoma. Treating the target volume at an isodose line of 50% or greater and avoiding whole-sellar radiosurgery, unless necessary, will likely mitigate the risk of post-GKRS hypopituitarism. Follow-up of these patients is required to detect and treat latent endocrinopathies.

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Amitabh Gupta, Zhiyuan Xu, Hideyuki Kano, Nathaniel Sisterson, Yan-Hua Su, Michal Krsek, Ahmed M. Nabeel, Amr El-Shehaby, Khaled A. Karim, Nuria Martínez-Moreno, David Mathieu, Brendan J. McShane, Roberto Martínez-Álvarez, Wael A. Reda, Roman Liscak, Cheng-Chia Lee, L. Dade Lunsford, and Jason P. Sheehan

OBJECTIVE

Gamma Knife radiosurgery (GKS) is typically used after failed resection in patients with Cushing’s disease (CD) and acromegaly. Little is known about the upfront role of GKS for patients with CD and acromegaly. In this study, the authors examine the outcome of upfront GKS for patients with these functioning adenomas.

METHODS

An international group of 7 Gamma Knife centers sent pooled data from 46 patients (21 with CD and 25 with acromegaly) undergoing upfront GKS to the coordinating center of the study for analysis. Diagnosis was established on the basis of clinical, endocrine, and radiological studies. All patients were treated on a common radiosurgical platform and longitudinally followed for tumor control, endocrine remission, and hypopituitarism. Patients received a tumor median margin dose of 25 Gy (range 12–40.0 Gy) at a median isodose of 50%.

RESULTS

The median endocrine follow-up was 69.5 months (range 9–246 months). Endocrine remission was achieved in 51% of the entire cohort, with 28% remission in acromegaly and 81% remission for those with CD at the 5-year interval. Patients with CD achieved remission earlier as compared to those with acromegaly (p = 0.0005). In patients post-GKS, the pituitary adenoma remained stable (39%) or reduced (61%) in size. Hypopituitarism occurred in 9 patients (19.6%), and 1 (2.2%) developed third cranial nerve (CN III) palsy. Eight patients needed further intervention, including repeat GKS in 6 and transsphenoidal surgery in 2.

CONCLUSIONS

Upfront GKS resulted in good tumor control as well as a low rate of adverse radiation effects in the whole group. Patients with CD achieved a faster and far better remission rate after upfront GKS in comparison to patients with acromegaly. GKS can be considered as an upfront treatment in carefully selected patients with CD who are unwilling or unable to undergo resection, but it has a more limited role in acromegaly.

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I. Jonathan Pomeraniec, Hideyuki Kano, Zhiyuan Xu, Brandon Nguyen, Zaid A. Siddiqui, Danilo Silva, Mayur Sharma, Hesham Radwan, Jonathan A. Cohen, Robert F. Dallapiazza, Christian Iorio-Morin, Amparo Wolf, John A. Jane Jr., Inga S. Grills, David Mathieu, Douglas Kondziolka, Cheng-Chia Lee, Chih-Chun Wu, Christopher P. Cifarelli, Tomas Chytka, Gene H. Barnett, L. Dade Lunsford, and Jason P. Sheehan

OBJECTIVE

Gamma Knife radiosurgery (GKRS) is frequently used to treat residual or recurrent nonfunctioning pituitary macroadenomas. There is no consensus as to whether GKRS should be used early after surgery or if radiosurgery should be withheld until there is evidence of imaging-defined progression of tumor. Given the high incidence of adenoma progression after subtotal resection over time, the present study intended to evaluate the effect of timing of radiosurgery on outcome.

METHODS

This is a multicenter retrospective review of patients with nonfunctioning pituitary macroadenomas who underwent transsphenoidal surgery followed by GKRS from 1987 to 2015 at 9 institutions affiliated with the International Gamma Knife Research Foundation. Patients were matched by adenoma and radiosurgical parameters and stratified based on the interval between last resection and radiosurgery. Operative results, imaging data, and clinical outcomes were compared across groups following early (≤ 6 months after resection) or late (> 6 months after resection) radiosurgery.

RESULTS

After matching, 222 patients met the authors’ study criteria (from an initial collection of 496 patients) and were grouped based on early (n = 111) or late (n = 111) GKRS following transsphenoidal surgery. There was a greater risk of tumor progression after GKRS (p = 0.013) and residual tumor (p = 0.038) in the late radiosurgical group over a median imaging follow-up period of 68.5 months. No significant difference in the occurrence of post-GKRS endocrinopathy was observed (p = 0.68). Thirty percent of patients without endocrinopathy in the early cohort developed new endocrinopathies during the follow-up period versus 27% in the late cohort (p = 0.84). Fourteen percent of the patients in the early group and 25% of the patients in the late group experienced the resolution of endocrine dysfunction after original presentation (p = 0.32).

CONCLUSIONS

In this study, early GKRS was associated with a lower risk of radiological progression of subtotally resected nonfunctioning pituitary macroadenomas compared with expectant management followed by late radiosurgery. Delaying radiosurgery may increase patient risk for long-term adenoma progression. The timing of radiosurgery does not appear to significantly affect the rate of delayed endocrinopathy.

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Mohana Rao Patibandla, Dale Ding, Hideyuki Kano, Zhiyuan Xu, John Y. K. Lee, David Mathieu, Jamie Whitesell, John T. Pierce, Paul P. Huang, Douglas Kondziolka, Caleb Feliciano, Rafael Rodriguez-Mercado, Luis Almodovar, Inga S. Grills, Danilo Silva, Mahmoud Abbassy, Symeon Missios, Gene H. Barnett, L. Dade Lunsford, and Jason P. Sheehan

OBJECTIVE

Due to the complexity of Spetzler-Martin (SM) Grade IV–V arteriovenous malformations (AVMs), the management of these lesions remains controversial. The aims of this multicenter, retrospective cohort study were to evaluate the outcomes after single-session stereotactic radiosurgery (SRS) for SM Grade IV–V AVMs and determine predictive factors.

METHODS

The authors retrospectively pooled data from 233 patients (mean age 33 years) with SM Grade IV (94.4%) or V AVMs (5.6%) treated with single-session SRS at 8 participating centers in the International Gamma Knife Research Foundation. Pre-SRS embolization was performed in 71 AVMs (30.5%). The mean nidus volume, SRS margin dose, and follow-up duration were 9.7 cm3, 17.3 Gy, and 84.5 months, respectively. Statistical analyses were performed to identify factors associated with post-SRS outcomes.

RESULTS

At a mean follow-up interval of 84.5 months, favorable outcome was defined as AVM obliteration, no post-SRS hemorrhage, and no permanently symptomatic radiation-induced changes (RIC) and was achieved in 26.2% of patients. The actuarial obliteration rates at 3, 7, 10, and 12 years were 15%, 34%, 37%, and 42%, respectively. The annual post-SRS hemorrhage rate was 3.0%. Symptomatic and permanent RIC occurred in 10.7% and 4% of the patients, respectively. Only larger AVM diameter (p = 0.04) was found to be an independent predictor of unfavorable outcome in the multivariate logistic regression analysis. The rate of favorable outcome was significantly lower for unruptured SM Grade IV–V AVMs compared with ruptured ones (p = 0.042). Prior embolization was a negative independent predictor of AVM obliteration (p = 0.024) and radiologically evident RIC (p = 0.05) in the respective multivariate analyses.

CONCLUSIONS

In this multi-institutional study, single-session SRS had limited efficacy in the management of SM Grade IV–V AVMs. Favorable outcome was only achieved in a minority of unruptured SM Grade IV–V AVMs, which supports less frequent utilization of SRS for the management of these lesions. A volume-staged SRS approach for large AVMs represents an alternative approach for high-grade AVMs, but it requires further investigation.

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Zhiyuan Xu, Cheng-Chia Lee, Arjun Ramesh, Adam C. Mueller, David Schlesinger, Or Cohen-Inbar, Han-Hsun Shih, and Jason P. Sheehan

OBJECTIVE

Recent advancements in molecular biology have identified the BRAF mutation as a common mutation in melanoma. The wide use of BRAF kinase inhibitor (BRAFi) in patients with metastatic melanoma has been established. The objective of this study was to examine the impact of BRAF mutation status and use of BRAFi in conjunction with stereotactic radiosurgery (SRS).

METHODS

This was a single-center retrospective study. Patient's charts and electronic records were reviewed for date of diagnosis of primary malignancy, BRAF mutation status, chemotherapies used, date of the diagnosis of CNS metastases, date of SRS, survival, local tumor control after SRS, and adverse events. Patients were divided into 3 groups: Group A, those with mutant BRAF without BRAFi treatment (13 patients); Group B, those with mutant BRAF with BRAFi treatment (17 patients); and Group C, those with wild-type BRAF (35 patients). Within a cohort of 65 patients with the known BRAF mutation status and treated with SRS between 2010 and 2014, 436 individual brain metastases (BMs) were identified. Kaplan-Meier methodology was then used to compare survival based on each binary parameter.

RESULTS

Median survival times after the diagnosis of melanoma BM and after SRS were favorable in patients with a BRAF mutation and treated with SRS in conjunction with BRAFi (Group B) compared with the patients with wild-type BRAF (Group C, 23 vs 8 months and 13 vs 5 months, respectively; p < 0.01, log-rank test). SRS provided a local tumor control rate of 89.4% in the entire cohort of patients. Furthermore, the local control rate was improved in the patients treated with SRS in conjunction with BRAFi (Group B) compared with patients with wild-type (Group C) or with BRAF mutation but no BRAFi (Group A) as an adjunct treatment for BMs.

CONCLUSIONS

BRAF mutation status appears to play an important role as a potent prognostic factor in patients harboring melanoma BM. BRAFi in conjunction with SRS may benefit this group of patients in terms of BM survival and SRS with an acceptable safety profile.