Relative survival rates and patterns of diagnosis analyzed by time period for individuals with primary malignant brain tumor, 1973–1997

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Abstract
Object. The purpose of this study was to examine patterns of diagnosis and relative survival rates in individuals in whom a primary malignant brain tumor was diagnosed between 1973 and 1997; follow-up review of these patients continued through the end of 1999. Methods. The study population was composed of 21,493 patients with primary malignant brain tumors that were diagnosed between 1973 and 1997. Data on these patients were obtained from the population-based Surveillance, Epidemiology, and End Results Program. The study population was divided into three cohorts based on the year of diagnosis, and these groups were compared with respect to variables of interest by performing chi-square tests and relative survival analysis with the life table method. Over time, there were consistently more men, more Caucasians, more patients undergoing surgery, and more individuals 70 years and older who received the diagnosis of primary malignant brain tumor. An examination of proportions of individuals with astrocytoma, other; oligodendroglioma, other; and oligodendroglioma Grade III showed significant temporal changes with frontal and temporal lobe tumors occurring most often. The diagnosis was obtained at an earlier age in African-American than in Caucasian patients. Caucasians had higher proportions of glioblastoma multiforme (GBM), which was associated with decreased survival times, and of oligodendroglioma, other, whereas African Americans had higher proportions of astrocytoma, other; ependymoma Grade II or III; and medulloblastoma, all of which were associated with increased survival times. The relative survival case demonstrated a continuous improvement over time, although older patients, those who underwent biopsy only, and those with GBMs continue to have the poorest survival times. The relative survival rates of African Americans consistently were similar or worse than those of Caucasians when the groups were stratified by prognostic factors. Conclusions. Over time, the relative survival rate of individuals with primary malignant brain tumor has improved and differences in survival are seen by examining the race of the patients.