Glioblastoma is the most common and most malignant primary brain tumour. Survival is short, only around 15 months. This thesis explores factors influencing survival time.

The first article showed that survival was significantly prolonged in the County of Jönköping, after the implementation of a new treatment regimen in 2006. In this regimen, patients receive chemotherapy and radiotherapy concomitantly, over six weeks followed by adjuvant chemotherapy given every four weeks over six months. The study shows that survival was prolonged by 110 days.

For the second article, a review of patient records of all 189 glioblastoma patients diagnosed in the County of Jönköping 2001-2016 was performed. Patients with cognitive impairment were more difficult to diagnose, had larger tumours, and survived four months shorter than patients without cognitive impairment. If epileptic seizures were the presenting symptom, the tumours were found to be smaller at the time of diagnosis and patients lived three months longer than patients with no seizures at onset.

To further explore the difference in survival for patients with different presenting symptoms the Swedish Brain Tumour Registry (SBTR) was used in the third paper. Using the SBTR, we analysed 1458 glioblastoma patients diagnosed between 2018 and 2021. Cognitive impairment was linked to significantly shorter survival—even after adjusting for age, performance status, tumour size, MGMT methylation, surgical resection grade, and oncological treatment—while epileptic seizures initially appeared beneficial on univariate analysis but lost significance after adjustment.

The fourth study analysed 7669 glioblastoma patients from SBTR (1999–2023). Survival has improved across all age groups, almost all treatments, and regions, and analysis of relative survival demonstrated that patients primarily died from their brain tumour rather than other causes. Although initial data showed regional differences in survival, these differences diminished after adjusting for demographic data (age and sex) and tumour-related factors (preoperative performance status, tumour size), highlighting the need to control for such factors when comparing treatment outcomes between hospitals, regions and countries.

In summary, this thesis shows that while glioblastoma survival has improved over time, the overall prognosis remains poor. Patients presenting with cognitive dysfunction have a significantly shorter survival—even after adjusting for age, tumour size, and treatment—which is a novel finding. These patients are also less likely to receive oncological treatment, likely due to concerns about their understanding and ability to cope with therapy. Although earlier studies suggested that epileptic seizures at presentation were a positive prognostic factor, our larger study indicates that this association is explained by other factors. Finally, we confirm the prognostic impacts of age, tumour size, preoperative performance status, MGMT promoter methylation status (in patients treated with alkylating agents), extent of surgery, and oncological treatment.