Abstract AIMS The Gliocova dataset uses linked English national cancer data on all 51,775 adult primary brain tumour patients diagnosed between 2013-2018. Here we present detailed analysis of first-line treatments of adult glioblastoma (GBM) patients. METHOD We identified all adults patients diagnosed with a GBM. We focused on the first line of treatment and we defined ‘maximal’ first-line treatment as surgical resection followed by chemo-radiotherapy with 59-60 Gy and with at least one cycle of adjuvant chemotherapy Temozolomide. RESULTS 15,294 patients were diagnosed with a glioblastoma (60% male) with a median age of 66. 79% of patients received some treatment, with younger patients more likely to be treated (>90%, 18 - 59; < 30%, > 80). 54% underwent debulking surgery; 23%, biopsy. 14% received ‘maximal’ treatment and 21%, none. Patients who had no treatment had a median survival of 2 months whereas patients who received ‘maximal’ treatment had a median survival of 16 months. CONCLUSION Most adult patients with a GBM in England have a histological diagnosis, and some oncological treatment. However, only 14% receive ‘maximal’ treatment. Of the 3222 patients who received none, some of these may have had purely private treatment; however, our dataset includes any private sector work undertaken in NHS hospitals. Survival remains poor, but outcomes in those receiving maximal treatment match those from clinical trials. However, most patients do not receive maximal treatment, and so the easiest route to improving outcomes may be optimise delivery of treatment in the 65% of patients who receive sub-maximal treatment. More information on https://blogs.imperial.ac.uk/gliocova