Keith Unger

Dr. Keith Unger


Research Focus & Metrics

Academic Career Length

17Years (2010-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 August 2010 in International Journal of Radiation Oncology, Biology, Physics
Verified
Journal Article
Closed access
KUKeith Unger
Keith Unger
CLChristopher E. Lominska
Christopher E. Lominska
JDJohn F. Deeken
John F. Deeken
BDBruce J. Davidson
Bruce J. Davidson
KNKenneth A. Newkirk
Kenneth A. Newkirk
KHK. William Harter
K. William Harter

18 May 2012 in Radiation Oncology
Verified
Journal Article
Open access
PDF file
CLChris E Lominska
Chris E Lominska
KUKeith Unger
Keith Unger
NNNadim M Nasr
Nadim M Nasr
NHNadim Haddad
Nadim Haddad
GGGreg Gagnon
Greg Gagnon
Local control rates are poor in the treatment of pancreatic cancer. We investigated the role of hypofractionated stereotactic body radiation therapy (SBRT) for salvage or boost treatment after conventional doses of external beam radiation therapy.

1 September 2011 in Neurosurgery
Verified
Journal Article
Closed access
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KUKeith Unger
Keith Unger
CLChristopher E. Lominska
Christopher E. Lominska
JCJune Chanyasulkit
June Chanyasulkit
PRPamela Randolph-Jackson
Pamela Randolph-Jackson
RWRobert L. White
Robert L. White
GGGregory J. Gagnon
Gregory J. Gagnon
Background: Peritumoral edema is a recognized complication following stereotactic radiosurgery (SRS). Objective: To evaluate the risk of posttreatment peritumoral edema following SRS for intracranial meningiomas and determine predictive factors. Methods: Between 2002 and 2008, 173 evaluable patients underwent CyberKnife or Gamma Knife SRS for meningiomas. Eighty-four patients (49%) had prior surgical resections, 13 patients had World Health Organization grade II (atypical) meningiomas, and 117 patients had a neurological deficit before SRS. Sixty-two tumors were in parasagittal, parafalcine, and convexity locations. The median tumor volume was 4.7 mL (range, 0.1–231.8 mL). The median prescribed dose and median prescribed biologically equivalent dose were 15 Gy (range, 9–40 Gy) and 67 Gy (range, 14–116 Gy), respectively. Ninety-seven patients were treated with single-fraction SRS, 74 received 2 to 5 fractions, and 2 received >5 fractions. Results: The median follow-up was 21.0 months. Thirteen patients (8%) developed symptomatic peritumoral edema, with a median onset time of 4.5 months (range, 0.2– 9.5 months). The 3-, 6-, 12-, and 24-month actuarial symptomatic edema rates were 2.9%, 4.9%, 7.7%, and 8.5%, respectively. The crude tumor control rate was 94%. On univariate analysis, large tumor volume (P = .01) and single-fraction SRS (P = .04) were predictive for development of posttreatment edema. Conclusion: SRS meningioma treatment demonstrated a low incidence of toxicity; however, large tumor volumes and single-fraction SRS treatment had an increased risk for posttreatment edema. Risk factors for edema should be considered in meningiomas treatment.

18 July 2016 in BMC Cancer
Verified
Journal Article
Open access
PDF file
AKAlexander Y. Kim
Alexander Y. Kim
KUKeith Unger
Keith Unger
HWHongkun Wang
Hongkun Wang
MPMichael J. Pishvaian
Michael J. Pishvaian
The purpose of this retrospective study was to evaluate the efficacy of incorporating trans-arterial radioembolization (TARE) with systemic chemotherapy in the treatment of liver-dominant metastatic pancreatic ductal adenocarcinoma, with the aim of destroying liver metastases and improving patient outcomes. We retrospectively evaluated 16 patients with liver-dominant metastatic pancreatic ductal adenocarcinoma who underwent TARE between February 2012 and August 2015; 15 of these patients also underwent concurrent systemic chemotherapy. Patient outcomes were assessed using Response Evaluation Criteria In Solid Tumors (RECIST), Version 1.1 and included disease response, median overall survival from the time of diagnosis of metastatic disease, and median overall survival following receipt of TARE. Treatment-related adverse events were assessed using Common Terminology Criteria for Adverse Events (CTCAE), Version 4.03. The median overall survival from the time of diagnosis of metastatic disease and following receipt of TARE was 22.0 and 12.5 months, respectively. Overall and liver specific disease response were assessed for 13 patients with follow-up imaging available at the time of study (range 2–13 weeks post TARE). Four patients (31 %) demonstrated partial response and five patients (38 %) had stable disease in the liver at follow-up. One patient developed grade 3 elevation of total bilirubin three months post-treatment and another patient developed radiation cholecystitis directly following TARE. No treatment-related grade 4 or 5 toxicities were seen. TARE can be safely combined with systemic chemotherapy for the treatment of liver-dominant metastatic pancreatic cancer. Patient outcomes following this treatment strategy are promising but prospective evaluations are needed to validate these preliminary findings.

1 January 2012 in Frontiers in Oncology
Verified
Journal Article
Open access
BGBeant Gill
Beant Gill
EOEric Oermann
Eric Oermann
AJAndrew Ju
Andrew Ju
SSSimeng Suy
Simeng Suy
XYXia Yu
Xia Yu
BCBrian T. Collins
Brian T. Collins
This retrospective analysis examines the local control and toxicity of five-fraction fiducial-free CyberKnife stereotactic body radiation therapy (SBRT) for single vertebral body (VB) metastases. All patients had favorable performance status (ECOG 0–1), oligometastatic disease, and no prior spine irradiation. A prescribed dose of 30–35 Gy was delivered in five fractions to the planning target volume (PTV) using the CyberKnife with X-sight spine tracking. Suggested maximum spinal cord and esophagus point doses were 30 and 40 Gy, respectively. A median 30 Gy (IQR, 30–35 Gy) dose was delivered to a median prescription isodose line of 70% (IQR, 65–77%) to 20 patients. At 34 months median follow-up (IQR, 25–40 months) for surviving patients, the 1- and 2-year Kaplan–Meier local control estimates were 80 and 73%, respectively. Two of the five local failures were infield in patients who had received irradiation to the gross tumor volume and three were paravertebral failures just outside the PTV in patients with prior corpectomy. No local failures occurred in patients who completed VB radiation alone. The 1- and 2-year Kaplan–Meier overall survival estimates were 80 and 57%, respectively. Most deaths were attributed to metastatic disease; one death was attributed to local recurrence. The mean maximum point doses were 26.4 Gy (SD, 5.1 Gy) to the spinal cord and 29.1 Gy (SD, 8.9 Gy) to the esophagus. Patients receiving maximum esophagus point doses greater than 35 Gy experienced acute dysphagia (Grade I/II). No spinal cord toxicity was documented. Five-fraction fiducial-free CyberKnife SBRT is an acceptable treatment option for newly diagnosed VB metastases with promising local control rates and minimal toxicity despite the close proximity of such tumors to the spinal cord and esophagus. A prospective study aimed at further enhancing local control by targeting the intact VB and escalating the total dose is planned.

26 October 2015 in Radiation Oncology
Verified
Journal Article
Open access
PDF file
JLJonathan W. Lischalk
Jonathan W. Lischalk
EOEric Oermann
Eric Oermann
SCSean Philip Collins
Sean Philip Collins
MNMani N. Nair
Mani N. Nair
VNVikram V. Nayar
Vikram V. Nayar
BCBrian T. Collins
Brian T. Collins
Achieving durable local control while limiting normal tissue toxicity with definitive radiation therapy in the management of high-risk brain metastases remains a radiobiological challenge. The objective of this study was to examine the local control and toxicity of a 5-fraction stereotactic radiosurgical approach for treatment of patients with inoperable single high-risk NSCLC brain metastases. This retrospective analysis examines 20 patients who were deemed to have “high-risk” brain metastases. High-risk tumors were defined as those with a maximum diameter greater than 2 cm and/or those located within an eloquent cortex. Patients were evaluated by a neurosurgeon prior to treatment and determined to be inoperable due to tumor or patient characteristics. Patients were treated using the CyberKnife® SRS system in 5 fractions to a total dose of 30 Gy, 35 Gy, or 40 Gy. Twenty patients with a median age of 65.5 years were treated from April 2010 to August 2014 in 5 fractions to a median total dose of 35 Gy. At a median follow up of 11.3 months local tumor control was observed in 18 of 20 metastases (90 %). Both local failures were observed in patients receiving a lower dose of 30 Gy. Median pre-treatment dexamethasone dose was 10 mg/day and median post-treatment nadir dose was 0 mg/day. Salvage intracranial therapy was required in 45 % of patients. Symptomatic radionecrosis was observed in 4 of 20 patients (20 %), two of which were treated to 40 Gy and the remainder to 35 Gy. Kaplan-Meier 1-year, 2-year, and median survival were calculated to be 45 %, 20 %, and 13.2 months, respectively. Five-fraction SRS to a total dose of 35 Gy appears to be a safe and effective management strategy for single high-risk NSCLC brain metastases, while a total dose of 40 Gy leads to an excess risk of neurotoxicity.