NIMG-04. MRI CHARACTERISTICS, TREATMENT APPROACH, PATTERN OF RELAPSE AND SURVIVAL FOR MULTICENTRIC GLIOBLASTOMA. A RETROSPECTIVE MONOCENTRIC STUDY

Abstract

Abstract INTRODUCTION Multicentric glioblastoma (m-GBM) is a rare GBM variant (6–13% of all GBM cases). Published data is scarce and focus largely on enhancing foci. We performed a retrospective study to determine the incidence, imaging characteristics, treatment, pattern of relapse and prognosis of m-GBM. METHODS The neuropathological database of our institution was surveyed for histological diagnosis of adult GBM diagnosed between 01/01/2015 and 31/05/2018. All pre-operative MRI were reviewed to identify patients with m-GBM (defined as well separated enhancing and non-enhancing tumor foci). Medical records and follow-up MRI studies were reviewed to retrieve the data. RESULTS Of the 167 patients with newly diagnosed GBM, 14 (8%) presented with m-GBM. All of them had at least one enhancing lesion. The total number of lesions was 37 (19 enhancing and 18 non-enhancing) with a median number of lesions per patient of 2 (range 2 to 4). Median age at diagnosis was 66 (range: 49–79) years. MGMT status was known for 10 patients (5 methylated and 5 un-methylated). Nine patients underwent resection of the enhancing component whereas 5 patients had a biopsy. Median follow up was 14.3 (range: 2–30) months. All but one patient were treated by concurrent radiotherapy with temozolomide. All enhancing lesions were included in radiation field, whereas 4 of the 18 Flair lesions were not. Median progression free survival was 6.2 (range: 0–13.3) months. Six of the 18 non-enhancing tumor foci eventually displayed contrast enhancement during the follow-up. At last follow up, 12 patients died, with an overall survival of 12.3 months. Information regarding radiation fields, pattern of progression and molecular profile will be presented at the meeting. CONCLUSION m-GBM presents therapeutic dilemmas regarding the optimal therapeutical approach. Better understanding of the disease course and pattern of progression may help to optimize the therapeutic approach implying particularly to non-enhancing tumor foci.