Search Results

You are looking at 1 - 10 of 14 items for

  • Author or Editor: Kevin Oh x
Clear All Modify Search
Restricted access

Gregory Neil Bowden, Jong Oh Kim, Andrew Faramand, Kevin Fallon, John Flickinger and L. Dade Lunsford

OBJECTIVE

The use of Gamma Knife stereotactic radiosurgery (GKSRS) for the treatment of extensive intracranial metastases has been expanding due to its superior dosimetry and efficacy. However, there remains a dearth of data regarding the dose parameters in actual clinical scenarios. The authors endeavored to calculate the radiation dose to the brain when treating ≥ 15 brain metastases with GKSRS.

METHODS

This retrospective analysis reviewed dosage characteristics for patients requiring single-session GKSRS for the treatment of ≥ 15 brain metastases. Forty-two patients met the inclusion criteria between 2008 and 2017. The median number of tumors at the initial GKSRS procedure was 20 (range 15–39 tumors), accounting for 865 tumors in this study. The median aggregate tumor volume was 3.1 cm3 (range 0.13–13.26 cm3), and the median marginal dose was 16 Gy (range 14–19 Gy).

RESULTS

The median of the mean brain dose was 2.58 Gy (range 0.95–3.67 Gy), and 79% of patients had a dose < 3 Gy. The 12-Gy dose volume was a median of 12.45 cm3, which was equivalent to 0.9% of the brain volume. The median percentages of brain receiving 5 Gy and 3 Gy were 6.7% and 20.4%, respectively. There was no correlation between the number of metastases and the mean dose to the brain (p = 0.8). A greater tumor volume was significantly associated with an increased mean brain dose (p < 0.001). The median of the mean dose to the bilateral hippocampi was 2.3 Gy. Sixteen patients had supplementary GKSRS, resulting in an additional mean dose of 1.4 Gy (range 0.2–3.8 Gy) to the brain.

CONCLUSIONS

GKSRS is a viable means of managing extensive brain metastases. This procedure provides a relatively low dose of radiation to the brain, especially when compared with traditional whole-brain radiation protocols.

Full access

Maha Saada Jawad, Daniel K. Fahim, Peter C. Gerszten, John C. Flickinger, Arjun Sahgal, Inga S. Grills, Jason Sheehan, Ronald Kersh, John Shin, Kevin Oh, Frederick Mantel and Matthias Guckenberger

OBJECTIVE

The purpose of this study was to identify factors contributing to an increased risk for vertebral compression fracture (VCF) following stereotactic body radiation therapy (SBRT) for spinal tumors.

METHODS

A total of 594 tumors were treated with spinal SBRT as primary treatment or re-irradiation at 8 different institutions as part of a multi-institutional research consortium. Patients underwent LINAC-based, image-guided SBRT to a median dose of 20 Gy (range 8–40 Gy) in a median of 1 fraction (range 1–5 fractions). Median patient age was 62 years. Seventy-one percent of tumors were osteolytic, and a preexisting vertebral compression fracture (VCF) was present in 24% of cases. Toxicity was assessed following treatment. Univariate and multivariate analyses were performed using a logistic regression method to determine parameters predictive for post-SBRT VCF.

RESULTS

At a median follow-up of 10.1 months (range 0.03–57 months), 80% of patients had local tumor control. At the time of last imaging follow-up, at a median of 8.8 months after SBRT, 3% had a new VCF, and 2.7% had a progressive VCF. For development of any (new or progressive) VCF following SBRT, the following factors were predictive for VCF on univariate analysis: short interval from primary diagnosis to SBRT (less than 36.8 days), solitary metastasis, no additional bone metastases, no prior chemotherapy, preexisting VCF, no MRI used for target delineation, tumor volume of 37.3 cm3 or larger, equivalent 2-Gy-dose (EQD2) tumor of 41.8 Gy or more, and EQD2 spinal cord Dmax of 46.1 Gy or more. Preexisting VCF, solitary metastasis, and prescription dose of 38.4 Gy or more were predictive on multivariate analysis. The following factors were predictive of a new VCF on univariate analysis: solitary metastasis, no additional bone metastases, and no MRI used for target delineation. Presence of a solitary metastasis and lack of MRI for target delineation remained significant on multivariate analysis.

CONCLUSIONS

A VCF following SBRT is more likely to occur following treatment for a solitary spinal metastasis, reflecting a more aggressive treatment approach in patients with adequately controlled systemic disease. Higher prescription dose and a preexisting VCF also put patients at increased risk for post-SBRT VCF. In these patients, pre-SBRT cement augmentation could be considered to decrease the risk of subsequent VCF.

Full access

Daniel Kim, Andrzej Niemierko, William L. Hwang, Anat O. Stemmer-Rachamimov, William T. Curry, Fred G. Barker II, Robert L. Martuza, Kevin S. Oh, Jay S. Loeffler and Helen A. Shih

OBJECTIVE

Patients with atypical and malignant (WHO Grade II and III) meningiomas have a worse prognosis than patients with benign (WHO Grade I) meningiomas. However, there is limited understanding of the pathological risk factors that affect long-term tumor control following combined treatment with surgery and radiation therapy. Here, the authors identify clinical and histopathological risk factors for the progression and/or recurrence (P/R) of high-grade meningiomas based on the largest series of patients with atypical and malignant meningiomas, as defined by the 2007 WHO classification.

METHODS

Patients diagnosed with WHO Grade II and III meningiomas between 2007 and 2014 per the WHO 2007 criteria and treated with both surgery and external beam radiation therapy were retrospectively reviewed for clinical and histopathological factors at the time of diagnosis and assessed for P/R outcomes at the last available follow-up.

RESULTS

A total of 76 patients met the inclusion criteria (66 Grade II meningiomas, 10 Grade III meningiomas). Median follow-up from the time of pathological diagnosis was 52.6 months. Three factors were found to predict P/R: Grade III histology, brain and/or bone invasion, and a Ki-67 proliferation rate at or above 3%. The crude P/R rate was 80% for patients with Grade III histology, 40% for those with brain and/or bone involvement (regardless of WHO tumor grade), and 20% for those with a proliferative index ≥ 3% (regardless of WHO tumor grade). The median proliferation index was significantly different between patients in whom treatment failed and those in whom it did not fail (11% and 1%, respectively).

CONCLUSIONS

In patients with atypical or malignant meningiomas, the presence of Grade III histology, brain and/or bone involvement, and a high mitotic index significantly predicted an increased risk of treatment failure despite combination therapy. These patients can be stratified into risk groups predicting P/R. Patients with high-risk features may benefit from more treatment and counseling than is typically offered currently.

Restricted access

Predicting tumor-specific survival in patients with spinal metastatic renal cell carcinoma: which scoring system is most accurate?

Presented at the 2020 AANS/CNS Joint Section on Disorders of the Spine and Peripheral Nerves

Elie Massaad, Muhamed Hadzipasic, Christopher Alvarez-Breckenridge, Ali Kiapour, Nida Fatima, Joseph H. Schwab, Philip Saylor, Kevin Oh, Andrew J. Schoenfeld, Ganesh M. Shankar and John H. Shin

OBJECTIVE

Although several prognostic scores for spinal metastatic disease have been developed in the past 2 decades, the applicability and validity of these models to specific cancer types are not yet clear. Most of the data used for model formation are from small population sets and have not been updated or externally validated to assess their performance. Developing predictive models is clinically relevant as prognostic assessment is crucial to optimal decision-making, particularly the decision for or against spine surgery. In this study, the authors investigated the performance of various spinal metastatic disease risk models in predicting prognosis for spine surgery to treat metastatic renal cell carcinoma (RCC).

METHODS

Data of patients who underwent surgery for RCC metastatic to the spine at 2 tertiary centers between 2010 and 2019 were retrospectively retrieved. The authors determined the prognostic value associated with the following scoring systems: the Tomita score, original and revised Tokuhashi scores, original and modified Bauer scores, Katagiri score, the Skeletal Oncology Research Group (SORG) classic algorithm and nomogram, and the New England Spinal Metastasis Score (NESMS). Regression analysis of patient variables in association with 1-year survival after surgery was assessed using Cox proportional hazard models. Calibration and time-dependent discrimination analysis were tested to quantify the accuracy of each scoring system at 3 months, 6 months, and 1 year.

RESULTS

A total of 86 metastatic RCC patients were included (median age 64 years [range 29–84 years]; 63 males [73.26%]). The 1-year survival rate was 72%. The 1-year survival group had a good performance status (Karnofsky Performance Scale [KPS] score 80%–100%) and an albumin level > 3.5 g/dL (p < 0.05). Multivariable-adjusted Cox regression analysis showed that poor performance status (KPS score < 70%), neurological deficit (Frankel grade A–D), and hypoalbuminemia (< 3.5 g/dL) were associated with a higher risk of death before 1 year (p < 0.05). The SORG nomogram, SORG classic, original Tokuhashi, and original Bauer demonstrated fair performance (0.7 < area under the curve < 0.8). The NESMS differentiates survival among the prognostic categories with the highest accuracy (area under the curve > 0.8).

CONCLUSIONS

The present study shows that the most cited and commonly used scoring systems have a fair performance predicting survival for patients undergoing spine surgery for metastatic RCC. The NESMS had the best performance at predicting 1-year survival after surgery.

Full access

Ariel E. Marciscano, Anat O. Stemmer-Rachamimov, Andrzej Niemierko, Mykol Larvie, William T. Curry, Fred G. Barker II, Robert L. Martuza, Declan McGuone, Kevin S. Oh, Jay S. Loeffler and Helen A. Shih

OBJECT

World Health Organization (WHO) Grade I (benign) meningiomas with atypical features may behave more aggressively than similarly graded tumors without atypical features. Here, the prognostic significance of atypical features in benign meningiomas was determined.

METHODS

Data from patients diagnosed with WHO Grade I benign meningiomas per the 2007 WHO criteria and who underwent surgery between 2002 and 2012 were retrospectively reviewed. Patients were stratified by the absence or presence of 1 to 2 atypical features with review of the clinical and histological factors.

RESULTS

A total of 148 patients met the inclusion criteria (n = 77 with atypia; n = 71 without atypia). The median follow-up duration after pathological diagnosis was 37.5 months. Thirty patients had progression/recurrence (P/R) after initial treatment, and 22 (73%) of 30 patients with P/R had 1–2 atypical features. The presence of atypical features was significantly associated with P/R (p = 0.03) and independent of the MIB-1 labeling index. The 1-year and 5-year actuarial rates of P/R were 9.6% versus 1.4% and 30.8% versus 13.8% fortumors with and without atypical features, respectively. Higher Simpson grade resection (II–IV vs I) was associated with the increased risk of P/R (p < 0.001). Stratification of patients into low-risk (Simpson Grade I), intermediate-risk (Simpson Grade II–IV with no atypical features), and high-risk groups (Simpson Grade II–IV with atypical features) was significantly correlated with increased risk of P/R (p < 0.001).

CONCLUSIONS

Patients with benign meningiomas with atypical features and those undergoing Simpson Grade II–IV resection are at significantly increased risk of P/R. Patients with these features may benefit from the consideration of additional surgery and/or radiation therapy.

Free access

J. Blair Price, Aaron E. Rusheen, Abhijeet S. Barath, Juan M. Rojas Cabrera, Hojin Shin, Su-Youne Chang, Christopher J. Kimble, Kevin E. Bennet, Charles D. Blaha, Kendall H. Lee and Yoonbae Oh

The development of closed-loop deep brain stimulation (DBS) systems represents a significant opportunity for innovation in the clinical application of neurostimulation therapies. Despite the highly dynamic nature of neurological diseases, open-loop DBS applications are incapable of modifying parameters in real time to react to fluctuations in disease states. Thus, current practice for the designation of stimulation parameters, such as duration, amplitude, and pulse frequency, is an algorithmic process. Ideal stimulation parameters are highly individualized and must reflect both the specific disease presentation and the unique pathophysiology presented by the individual. Stimulation parameters currently require a lengthy trial-and-error process to achieve the maximal therapeutic effect and can only be modified during clinical visits. The major impediment to the development of automated, adaptive closed-loop systems involves the selection of highly specific disease-related biomarkers to provide feedback for the stimulation platform. This review explores the disease relevance of neurochemical and electrophysiological biomarkers for the development of closed-loop neurostimulation technologies. Electrophysiological biomarkers, such as local field potentials, have been used to monitor disease states. Real-time measurement of neurochemical substances may be similarly useful for disease characterization. Thus, the introduction of measurable neurochemical analytes has significantly expanded biomarker options for feedback-sensitive neuromodulation systems. The potential use of biomarker monitoring to advance neurostimulation approaches for treatment of Parkinson’s disease, essential tremor, epilepsy, Tourette syndrome, obsessive-compulsive disorder, chronic pain, and depression is examined. Further, challenges and advances in the development of closed-loop neurostimulation technology are reviewed, as well as opportunities for next-generation closed-loop platforms.

Full access

Ahmed Hashmi, Matthias Guckenberger, Ron Kersh, Peter C. Gerszten, Frederick Mantel, Inga S. Grills, John C. Flickinger, John H. Shin, Daniel K. Fahim, Brian Winey, Kevin Oh, B. C. John Cho, Daniel Létourneau, Jason Sheehan and Arjun Sahgal

OBJECTIVE

This study is a multi-institutional pooled analysis specific to imaging-based local control of spinal metastases in patients previously treated with conventional external beam radiation therapy (cEBRT) and then treated with re-irradiation stereotactic body radiotherapy (SBRT) to the spine as salvage therapy, the largest such study to date.

METHODS

The authors reviewed cases involving 215 patients with 247 spinal target volumes treated at 7 institutions. Overall survival was calculated on a patient basis, while local control was calculated based on the spinal target volume treated, both using the Kaplan-Meier method. Local control was defined as imaging-based progression within the SBRT target volume. Equivalent dose in 2-Gy fractions (EQD2) was calculated for the cEBRT and SBRT course using an α/β of 10 for tumor and 2 for both spinal cord and cauda equina.

RESULTS

The median total dose/number of fractions of the initial cEBRT was 30 Gy/10. The median SBRT total dose and number of fractions were 18 Gy and 1, respectively. Sixty percent of spinal target volumes were treated with single-fraction SBRT (median, 16.6 Gy and EQD2/10 = 36.8 Gy), and 40% with multiple-fraction SBRT (median 24 Gy in 3 fractions, EQD2/10 = 36 Gy). The median time interval from cEBRT to re-irradiation SBRT was 13.5 months, and the median duration of patient follow-up was 8.1 months. Kaplan-Meier estimates of 6- and 12-month overall survival rates were 64% and 48%, respectively; 13% of patients suffered a local failure, and the 6- and 12-month local control rates were 93% and 83%, respectively. Multivariate analysis identified Karnofsky Performance Status (KPS) < 70 as a significant prognostic factor for worse overall survival, and single-fraction SBRT as a significant predictive factor for better local control. There were no cases of radiation myelopathy, and the vertebral compression fracture rate was 4.5%.

CONCLUSIONS

Re-irradiation spine SBRT is effective in yielding imaging-based local control with a clinically acceptable safety profile. A randomized trial would be required to determine the optimal fractionation.

Free access

Alexander F. Haddad, Jacob S. Young, Taemin Oh, Matheus P. Pereira, Rushikesh S. Joshi, Kaitlyn M. Pereira, Robert C. Osorio, Kevin C. Donohue, Zain Peeran, Sweta Sudhir, Saket Jain, Angad Beniwal, Ashley S. Chopra, Narpal S. Sandhu, Philip V. Theodosopoulos, Sandeep Kunwar, Ivan H. El-Sayed, José Gurrola II, Lewis S. Blevins Jr. and Manish K. Aghi

OBJECTIVE

Nonfunctioning pituitary adenomas present without biochemical or clinical signs of hormone excess and are the second most common type of pituitary adenomas. The 2017 WHO classification scheme of pituitary adenomas differentiates null-cell adenomas (NCAs) and silent gonadotroph adenomas (SGAs). The present study sought to highlight the differences in patient characteristics and clinical outcomes between NCAs and SGAs.

METHODS

The records of 1166 patients who underwent transsphenoidal surgery for pituitary adenoma between 2012 and 2019 at a single institution were retrospectively reviewed. Patient demographics and clinical outcomes were collected.

RESULTS

Of the overall pituitary adenoma cohort, 12.8% (n = 149) were SGAs and 9.2% (n = 107) NCAs. NCAs were significantly more common in female patients than SGAs (61.7% vs 26.8%, p < 0.001). There were no differences in patient demographics, initial tumor size, or perioperative and short-term clinical outcomes. There was no significant difference in the amount of follow-up between patients with NCAs and those with SGAs (33.8 months vs 29.1 months, p = 0.237). Patients with NCAs had significantly higher recurrence (p = 0.021), adjuvant radiation therapy usage (p = 0.002), and postoperative diabetes insipidus (p = 0.028). NCA pathology was independently associated with tumor recurrence (HR 3.64, 95% CI 1.07–12.30; p = 0.038), as were cavernous sinus invasion (HR 3.97, 95% CI 1.04–15.14; p = 0.043) and anteroposterior dimension of the tumor (HR 2.23, 95% CI 1.09–4.59; p = 0.030).

CONCLUSIONS

This study supports the definition of NCAs and SGAs as separate subgroups of nonfunctioning pituitary adenomas, and it highlights significant differences in long-term clinical outcomes, including tumor recurrence and the associated need for adjuvant radiation therapy, as well as postoperative diabetes insipidus. The authors also provide insight into independent risk factors for these outcomes in the adenoma population studied, providing clinicians with additional predictors of patient outcomes. Follow-up studies will hopefully uncover mechanisms of biological aggressiveness in NCAs and associated molecular targets.