LAUSR

To study clinical features and treatment options between 2007–2018 in a population of diffuse low grade glioma (DLGG) patients (WHO Grade2). Single centre retrospective cohort study. Variables reviewed: demographics, extent of resection (biopsy – Bx, subtotal resection – STR, gross total resection – GTR), molecular genetics and outcome. N=104.M=61 F=43, average age, 41.8 yrs. For their first surgery, 40.4% underwent a Bx, 32.7% STR, 26.9% GTR. 50.9% of patients had a second procedure due to clinical progression (13.8% Bx, 38.85% STR, 47.2% GTR). We were more surgically aggressive at the second sitting (p=0.0021). After 2014, we were more aggressive in terms of achieving a resection over a biopsy alone (pre 2013: 26 Bx, 24 resection, post 2013: 15 Bx, 28 resection). 35% had 1p19q co-deletion, 70% had 1DH1 mutation and 44.6% with MGMT methylated. There was no difference in survival and extent of resection in 1p19 co-deletions (HR 0.35), however there was in the IDH 1 group (HR 1.25. Post operatively, 37.9% patients had chemotherapy and 57.3 % radiotherapy. 80.5% (Bx 65,9% alive, resection 95% alive) of patients are still alive (longest survival 11.6 yrs). Amongst those who died, the mean overall survival was 4.0 (range 0–7 - 5 years): Of these 14% had undergone a Bx and 6% STR/GTR. The adjusted analysis revealed that EOR is the only revelant factor for survival in the population when adjusted for IDH, 1p19q, tumour volume, age, gender and surgery year (p=0.44). Our data emphasises the importance of achieving maximal resection when possible.