CXCL8 and glioblastoma: Recent studies have reported that GBM tumor cells may increase the neutrophil count both in the peripheral blood and around the tumor by secreting chemotactic factors, including G-CSF, VEGF, IL-1β, and IL-6, and neutrophils may promote tumor progression by secreting important cytokines, such as VEGF, IL-6, IL-8, elastases, and matrix metalloproteinases (30, 31).