PTEN is a tumor suppressor gene, located on chromosome 10q23, and loss of PTEN results in upregulation of the PI3K/ AKT pathway. Loss of PTEN may occur due to homozygous deletion, nonsense mutations, promoter hypermethylation, or with loss of heterozygosity (LOH). In prostate cancer, homozygous deletions spanning the PTEN locus occurs at one of the highest rates of any tumor type studied thus far. PTEN mutations may occur in multiple exons. Approximately in 25%-70% of prostate cancer, PI3K pathway has been altered either through PI3k overactivation or PTEN inactivation. PTEN is inactivated mainly through deletion in nearly 40%, or mutations in about 10%; both are more common in advanced prostate cancer.