P11.03.A DOES REGULAR SURVEILLANCE IMAGING IMPROVE SURVIVAL IN GLIOBLASTOMA? RESULTS FROM A NATIONAL, MULTI-CENTRE COHORT STUDY (INTERVAL-GB)

Abstract

Abstract BACKGROUND Glioblastoma is the most common malignant primary brain tumour in adults and is usually incurable. Post-operative magnetic resonance imaging (MRI) is used to assess extent of resection, and subsequent follow-up MRI is used to monitor response to treatment and to detect progression. The benefit of regular, scheduled follow-up MRI on patient management and outcomes is unclear. MATERIAL AND METHODS In this multi-centre, retrospective observational cohort study we included patients with a histopathologically confirmed glioblastoma, operated between August 31, 2018 and February 1, 2019 who received any adjuvant oncological treatment. Follow-up MRI schedules, indications, and clinical outcomes were collected. The primary objective was to investigate the follow-up MRI surveillance practice after surgery for glioblastoma and assess compliance with recommendations from the National Institute for Health and Care Excellence (NICE) (Post-operative scan <72 hrs, MRI every 3-6 months). The secondary objectives were to determine indications for MRI scans and the association on overall survival (OS) and progression-free survival (PFS). RESULTS 754 patients, with a median age of 63 years (range: 21-84) from 26 neuro-oncology centres were included. Most patients had post-operative MRI within 72 hours of surgery (88.1%, N=407/462). The median number of subsequent follow-up MRI was 1 (Interquartile range 0-4). 28.1% of patients had follow-up MRI in accordance with NICE recommendations (N=212/754). Patients in this group were more likely to receive second-line chemotherapy (28.6% vs 19.5%, P=0.009). The median follow-up period was 10.5 months (IQR 5.3-19.4 months). Median overall survival was 15.1 months (95% CI 12.9-17.3) in the scheduled MRI group and 9.1 months (95% CI 7.8-10.4) in the non-compliant group. On multivariable cox regression analysis, regular, scheduled MRI was independently associated with longer overall survival (HR 1.67, 95% CI 1.33-2.10, P<0.001), but not PFS (HR 1.20, 95% CI 0.98-1.47, P=0.074). Patients with progression first detected on scheduled imaging had a significantly longer OS (18.4 vs 15.6 months, P=0.013) and PFS (9.9 months vs 7.9 months, P=0.041). CONCLUSION Following regular scheduled surveillance follow-up MRI for glioblastoma is associated with longer overall survival. Prospective trials are needed to determine whether regular or symptom-directed MRI influences survival outcomes and quality of life.