Early postoperative tumor progression predicts clinical outcome in glioblastoma—implication for clinical trials
J Neurooncol
Early postoperative tumor progression predicts clinical outcome in glioblastoma-implication for clinical trials
Andreas Merkel 0 1 2 3
Dorothea Soeldner 0 1 2 3
Christina Wendl 0 1 2 3
Dilek Urkan 0 1 2 3
Joji B. Kuramatsu 0 1 2 3
Corinna Seliger 0 1 2 3
Martin Proescholdt 0 1 2 3
Ilker Y. Eyupoglu 0 1 2 3
Peter Hau 0 1 2 3
Martin Uhl 0 1 2 3
Martin Uhl 0 1 2 3
0 Department of Neurology, University Hospital, Friedrich-Alexander University Erlangen-Nuremberg , Schwabachanlage 6, 91054 Erlangen , Germany
1 Department of Neuroradiology, University of Regensburg , Regensburg , Germany
2 Department of Neurology and Wilhelm Sander-NeuroOncology Unit, University of Regensburg , Regensburg , Germany
3 Department of Neurosurgery, University of Regensburg , Regensburg , Germany
Molecular markers define the diagnosis of glioblastoma in the new WHO classification of 2016, challenging neuro-oncology centers to provide timely treatment initiation. The aim of this study was to determine whether a time delay to treatment initiation was accompanied by signs of early tumor progression in an MRI before the start of radiotherapy, and, if so, whether this influences the survival of glioblastoma patients. Images from 61 patients with early post-surgery MRI and a second MRI just before the start of radiotherapy were examined retrospectively for signs of early tumor progression. Survival information was analyzed using the Kaplan-Meier method, and a Cox multivariate analysis was performed to identify independent variables for survival prediction. 59 percent of patients showed signs of early tumor progression after a mean time of 24.1 days from the early post-surgery MRI to the start of radiotherapy. Compared to the group without signs of early tumor progression, which had a mean time of 23.3 days (p = 0.685, Student's t test), progression free survival was reduced from 320 to 185 days (HR 2.3; CI 95% 1.3-4.0; p = 0.0042, log-rank test) and overall survival from 778 to 329 days (HR 2.9; CI 95% 1.6-5.1; p = 0.0005). A multivariate Cox regression analysis revealed that the Karnofsky performance score, O-6-methylguanine-DNA-methyltransferase (MGMT) promoter methylation, and signs of early tumor progression are prognostic markers of overall survival. Early tumor progression at the start of radiotherapy is associated with a worse prognosis for glioblastoma patients. A standardized baseline MRI might allow for better patient stratification.
Glioblastoma; MGMT promoter; Treatment delay; Magnetic resonance imaging; Survival
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Department of Neurosurgery, Friedrich-Alexander University
Erlangen-Nuremberg, Erlangen, Germany
Introduction
Malignant gliomas are the most common brain tumor
entity, and from those, glioblastoma is one of the most
threatening. The current first-line treatment protocol
includes surgery followed by combined radio- and
chemotherapy [
1
]. Although this treatment protocol is very
aggressive, the median survival time of 14 months reflects
a poor prognosis. It is a common sentiment that an early
treatment initiation is important for optimal tumor control.
Nevertheless, reliable prospective data supporting this are
lacking. Where one retrospective analysis indicated that
delaying radiotherapy increased the risk of death by 9%
weekly [
2
], others showed no evidence of an effect on
overall survival [
3, 4
]. Today most oncologists would agree that
delaying the initiation of radiotherapy for up to 4 weeks
after tumor resection is not harmful [
5, 6
].
Given the dismal prognosis, new therapeutic concepts
are needed urgently and require prospective evaluation
within clinical trials. In the neuro-oncological field,
reference histology and molecular marker evaluation with
O-6-methylguanine-DNA-methyltransferase (MGMT)
promoter methylation are now widely used for molecular
analysis of glioblastoma for inclusion in clinical trials (e.g.
Centric, Glarius). It is likely that up-and-coming markers
such as the mutated isocitrate dehydrogenase, which is now
an integral standard in the amended WHO classification
[
7
], will also require more upfront testing time for patients
in the future. This implies a potential critical delay in
treatment initiation that could endanger the treatment outcome,
especially if the markers are evaluated centrally within a
clinical trial [
8
].
We examined retrospectively the MRIs and clinical
course of 61 glioblastoma patients in their first-line
treatment and addressed whether the MRI signs of early tumor
progression, which occur during the waiting time to
treatment initiation, are prognostic of survival.
Materials and methods
Patient selection
We screened our database from the years 2009 to 2013 for
patients with a histologically confirmed diagnosis of
glioblastoma that had post-surgery MRI as well as a baseline
MRI before start of radiotherapy. Patients were identified
according to the inclusion criteria of having a
well-documented clinical course and sufficient (...truncated)