Statistical Analysis
Chi-square tests were used to assess differences in the independent
variables of interest across the four racial groups. Kaplan-Meier curves
were used to estimate the unadjusted overall survival by race. The log
rank test was used to estimate the differences in survival among the
racial groups. Multivariable Cox proportional hazards models were used
to determine the differences in overall risk of mortality in the study
sample based on the independent variables including race, age at
diagnosis, Yost Quintile, stage, tumor grade, histology, radiation,
chemotherapy, and surgery.. All Chi-square tests and survival analyses
were conducted using SAS version 9.4 statistical software, with p-values
<0.05 considered significant.