CXCL8 and glioblastoma: Next, GBM patients were stratified based on IL-8 mRNA expression using quartile (Q1, Q3) split points; the lowest IL-8 quartile exhibited significantly higher median survival (Fig. 2b) (All GBM: IL-8-down 15.1 months, IL-8-up 12.6 months, hazard ratio (HR) [95% CI] = 0.71 [0.54, 0.93], log-rank p-value = 0.0112).