Letter regarding Xiao WZ et al. entitled "Relationships between PTEN gene mutations and prognosis in glioma: a meta-analysis".

With great interest, we read the article "Relationships between PTEN gene mutations and prognosis in glioma: a meta-analysis" (by Xiao et al. Tumor Biol 35(7):6687-6693, 2014), which has reached important conclusions that the phosphatase and tensin homolog (PTEN) gene mutations were closely related to poor prognosis of glioma patients. Through quantitative analysis, the investigators (Xiao WZ et al.) showed that glioma patients with PTEN gene mutations exhibited a significantly shorter overall survival (OS) than those without PTEN gene mutations (HR = 3.66, 95 % CI = 2.02∼5.30, P < 0.001). Ethnicity-stratified subgroup analysis demonstrated that PTEN gene mutations were closely linked to poor prognosis in glioma among Americans (HR = 3.72, 95 % CI = 1.72∼5.73, P < 0.001), while similar correlations were not observed among populations in Sweden, Italy, and Malaysia (all P > 0.05). The meta-analysis results are encouraging. Nevertheless, some deficiencies still existed that we would like to raise.