Abstract
Multiparametric advanced MR and [18F]fluorodeoxyglucose (FDG)-positron emission tomography (PET) imaging may be important biomarkers for prognosis as well for distinguishing recurrent glioblastoma multiforme (GBM) from treatment-related changes. We retrospectively evaluated 30 patients treated with chemoradiation for GBM and underwent advanced MR and FDG-PET for confirmation of tumor progression. Multiparametric MRI and FDG-PET imaging metrics were evaluated for their association with 6-month overall (OS) and progression-free survival (PFS) based on pathological, radiographic, and clinical criteria. 17 males and 13 females were treated between 2001 and 2014, and later underwent FDG-PET at suspected recurrence. Baseline FDG-PET and MRI imaging was obtained at a median of 7.5 months [interquartile range (IQR) 3.7-12.4] following completion of chemoradiation. Median follow-up after FDG-PET imaging was 10 months (IQR 7.2-13.0). Receiver-operator characteristic curve analysis identified that lesions characterized by a ratio of the SUVmax to the normal contralateral brain (SUVmax/NB index) >1.5 and mean apparent diffusion coefficient (ADC) value of ≤1,400 × 10-6 mm2/s correlated with worse 6-month OS and PFS. We defined three patient groups that predicted the probability of tumor progression: SUVmax/NB index >1.5 and ADC ≤1,400 × 10-6 mm2/s defined high-risk patients (n = 7), SUVmax/NB index ≤1.5 and ADC >1,400 × 10-6 mm2/s defined low-risk patients (n = 11), and intermediate-risk (n = 12) defined the remainder of the patients. Median OS following the time of the FDG-PET scan for the low, intermediate, and high-risk groups were 23.5, 10.5, and 3.8 months (p < 0.01). Median PFS were 10.0, 4.4, and 1.9 months (p = 0.03). Rates of progression at 6-months in the low, intermediate, and high-risk groups were 36, 67, and 86% (p = 0.04). Recurrent GBM in the molecular era is associated with highly variable outcomes. Multiparametric MR and FDG-PET biomarkers may provide a clinically relevant, non-invasive and cost-effective method of predicting prognosis and improving clinical decision making in the treatment of patients with suspected tumor recurrence.
Highlights
Significant advancements in the treatment of glioblastoma multiforme (GBM) have occurred in recent decades, survival outcomes remain poor
Methods/materials: We retrospectively evaluated 30 patients treated with chemoradiation for GBM and underwent advanced MR and FDG-positron emission tomography (PET) for confirmation of tumor progression
We retrospectively identified 30 patients with pathologically confirmed GBM (WHO grade IV) who received treatment consisting of biopsy or surgery, external beam radiation therapy, and concurrent and adjuvant temozolomide [1] between 2001 and 2014; and subsequently developed an enhancing lesion on conventional contrast-enhanced MRI that was presumed to be suspicious, but not definitive, for tumor progression according to the Response Assessment in Neuro-Oncology Criteria (RANO) Criteria [8] and review at multidisciplinary tumor board
Summary
Significant advancements in the treatment of glioblastoma multiforme (GBM) have occurred in recent decades, survival outcomes remain poor. Differentiating tumor progression from post-treatment radiographic changes, including radionecrosis, is vital to provide patients with appropriate salvage therapies to extend life and avoid unnecessary toxicity for those without evidence of disease. The advent of new modalities to detect tumor progression earlier in the surveillance period may translate to improved survival for patients with GBM. Assessing GBM response to therapy has been a challenging and controversial aspect of post-treatment oncologic management. Current National Comprehensive Cancer Network guidelines for GBM treatment response surveillance recommend conventional brain MRI 2–6 weeks after radiation therapy, followed by MRI every 2–3 months for the 2–3 years, and less frequent imaging thereafter [4]. The recently published Response Assessment in Neuro-Oncology Criteria (RANO) criteria improved the accuracy of follow-up imaging; identification of tumor progression remains a formidable challenge [8]
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