PTEN and central nervous system cancer: Downregulation of PTEN with negative impact on prognosis has already been described for prostate cancer, colorectal and breast cancer and high-grade gliomas (Korshunov et al, 2004; Fujita et al, 2006; Frattini et al, 2007; Yoshimoto et al, 2007; Laurent-Puig et al, 2009).