High levels of c-Met is associated with poor prognosis in glioblastoma

The tyrosine kinase receptor c-Met has been suggested to be involved in crucial parts of glioma biology like tumor stemness, growth and invasion. The aim of this study was to investigate the prognostic value of c-Met in a population-based glioma patient cohort. Tissue samples from 238 patients with WHO grade I, II, III and IV tumors were analyzed using immunohistochemical staining and advanced image analysis. Strong c-Met expression was found in tumor cells, blood vessels, and peri-necrotic areas. At the subcellular level, c-Met was identified in the cytoplasm and in the cell membrane. Measurements of high c-Met intensity correlated with high WHO grade (p = 0.006) but no association with survival was observed in patients with WHO grade II (p = 0.09) or III (p = 0.17) tumors. High expression of c-Met was associated with shorter overall survival in patients with glioblastoma multiforme (p = 0.03). However the prognostic effect of c-Met in glioblastomas was time-dependent and only observed in patients who survived more than 8.5 months, and not within the first 8.5 months after diagnosis. This was significant in multivariate analysis (HR 1.99, 95 % CI 1.29–3.08, p = 0.002) adjusted for treatment and the clinical variables age (HR 1.01, 95 % CI 0.99–1.03, p = 0.30), performance status (HR 1.34, 95 % CI 1.17–1.53, p < 0.001), and tumor crossing midline (HR 1.28, 95 % CI 0.79–2.07, p = 0.29). In conclusion, this study showed that high levels of c-Met holds unfavorable prognostic value in glioblastomas.