Evaluating short-term survivors of glioblastoma: A proposal based on SEER registry data

Glioblastomas (GBMs) are central nervous system tumors with a poor prognosis and limited treatment options. Although small subsets of GBM patients survive longer than 3 years, there is little evidence regarding the prognostic factors of GBM. Therefore, we conducted a thorough characterization of GBM in the United States.

We queried the Surveillance, Epidemiology, and End Results database between 2000 and 2021 to extract age-adjusted incidence rates (AAIRs), age-adjusted mortality rates (AAMRs), and survival data for GBM. We compared trends in AAIR, AAMR, and survival time across age groups 0-14, 15-39, 40-69, and 70+ years. Also, we employed the Fine-Gray competing risk model among short-term survivors (STSs), defined as those with a survival time of 6 months or less, and long-term survivors (LTSs), defined as those with a survival time of 3 years or more.

This study included 60 615 incident GBM cases, 54 998 GBM-specific deaths, and 47 207 GBM patients with available survival time between 2000 and 2021. The mortality-to-incidence ratio was constant among STSs, whereas it increased with age among LTSs. Higher age and male sex were significantly associated with GBM-specific death among LTSs, whereas non-Hispanic White and less intensive treatments were associated with GBM-specific deaths among STSs. Interestingly, higher age was significantly associated with other causes of death among STSs.

STSs partially consist of populations who died from causes other than GBM. It is important to include only GBM-specific deaths in STS groups to conduct reproducible research comparing STSs and LTSs.