Progressive Low-Grade Glioma: Assessment of Prognostic Importance of Histologic Reassessment and MRI Findings.
BACKGROUND
In patients with progressive low-grade glioma (LGG), the presence of new magnetic resonance imaging (MRI) enhancement is commonly used as an indicator of malignant degeneration, but its accuracy in this setting is uncertain.


OBJECTIVE
We characterize the ability of new MRI enhancement to serve as a surrogate for histologic grade in patients with progressive LGG, and to explore the prognostic value of new MRI enhancement, pathologic grade, and extent of resection.


METHODS
Patients at our institution with World Health Organization grade II glioma diagnosed between 1994 and 2010 and who underwent repeat biopsy or resection at progression were retrospectively reviewed (n = 108). The positive predictive value, negative predictive value, sensitivity, and specificity of new MRI enhancement were characterized. A multivariable proportional hazards model was used to test associations with overall survival (OS), and Kaplan-Meier curves were constructed to compare OS between patient subsets.


RESULTS
The positive predictive value, negative predictive value, sensitivity, and specificity of new MRI enhancement were 82%, 77%, 92%, and 57%, respectively. In patients without malignant degeneration, new MRI enhancement was associated with inferior median OS (92.5 months vs. not reached; P = 0.03). In patients with malignant degeneration, gross or near total resection was associated with improved median OS (58.8 vs. 28.8 months; P = 0.02).


CONCLUSIONS
In patients with progressive LGG, new MRI enhancement and pathologic grade were discordant in greater than 20% of cases. Pathologic confirmation of grade should therefore be attempted, when safe, to dictate management. Beyond functioning as a surrogate for pathologic grade, new MRI enhancement may predict for worse outcomes, a concept that merits prospective investigation.
Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
Amol K
AK
Narang
Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
Kaisorn L
KL
Chaichana
Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
Jon D
JD
Weingart
Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
Kristin J
KJ
Redmond
Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA; Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
Michael
M
Lim
Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
Alessandro
A
Olivi
Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
Alfred
A
Quinones-Hinojosa
Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA. Electronic address: kleinla@jhmi.edu.
Lawrence R
LR
Kleinberg
D000293:Adolescent; D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D018450:Disease Progression; D005260:Female; D005910:Glioma / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D006801:Humans; D053208:Kaplan-Meier Estimate; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D060787:Neoplasm Grading; D019635:Neurosurgical Procedures; D011237:Predictive Value of Tests; D011379:Prognosis; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D015996:Survival Rate; D055815:Young Adult
Low-grade glioma; MRI contrast enhancement; Malignant degeneration; Progression