Five-year survival in patients with Glioblastoma is overestimated in registry data - A nationwide population-based Swedish survey during 1958 - 1999

Abstract Background Some glioblastoma (GBM) patients survive more than five years with hitherto no clearly established epidemiological or molecular causes. Since varying rates of GBM five-year survival have been reported our aim was to assess the true prevalence of five-year survivors in Sweden from 1958 to 1999, before the introduction of concomitant temozolomide treatment.Methods After screening the Swedish Cancer Registry and the Cause of Death Register 736 out of 12765 patients with high-grade glioma were defined as five-year survivors. The full text pathology report was reviewed in 585 patients. Data on epidemiology and treatment were retrieved from the medical records of 556 patients.Results 77 five-year survivors with primary GBM were identified which corresponded to 0.60 % of the initial population. During 1990 to 1999 GBM five-year survival was 0. 90%. Younger age, Karnofsky score > 70 and non-eloquent tumour location were found in most but not all five-year survivors.Conclusion GBM five-year survival was exceedingly rare in Sweden until 2004, comprising less than 1 % of registered HGGs. Relying on registry data without reviewing the pathology report will overestimate the accurate number of five-year survivors. To our knowledge, this is the only nationwide population-based study of five-year survival in GBM patients.