Unveiling regional differences in glioblastoma patient survival with real-world data from the Norwegian brain tumor quality registry.

Purpose: Surveillance of patient outcomes with real-world data is essential to uncover regional disparities in clinical practice or quality of care. This study explored survival differences among glioblastoma patients in Norway and investigated the role of demographic and treatment factors.

Methods: We analyzed real-world data from the Norwegian Cancer Registry on 1158 adults with histologically confirmed glioblastoma during 2019-2023. Surgical treatment rates per 100,000 inhabitants per region (South-East, West, Mid, North) were compared using adjusted Poisson models. Full treatment included surgical resection, radiotherapy (≥ 55 Gy for ≤ 70 years; ≥30 Gy for > 70 years), and temozolomide. Standardized survival was estimated with flexible parametric models, standardized for age, sex, year, and distances to treatment facilities.

Results: Patients from the North were older and lived further from treatment centers. For patients aged 18-70, treatment and survival did not significantly differ across regions; national median standardized survival was 14.4 months (95%CI:13.6-15.2). For elderly patients (71-89 years), the North demonstrated a higher surgical treatment rate (rate ratio = 1.32; 95%CI = 0.99-1.77), but lesser use of postoperative radiotherapy and temozolomide. Median standardized survival for elderly patients in the North was 4.5 months (95%CI: 3.5-5.7) versus 7.7 (6.9-8.6) months nationally. Early mortality was particularly high for elderly patients in the North, yet those surviving beyond six months matched other regions' survival probability.

Conclusion: Lower glioblastoma survival in the North was associated with higher early mortality among elderly patients, likely due to selecting frailer patients for surgery, who less often subsequently received anti-neoplastic treatment.