KLK3 and prostate cancer: Prostate cancer (PCa) is the most commonly diagnosed non-skin cancer and the second leading cause of cancer death in man in United State.[1] In China, approximate 60,300 new cancer cases and 26,600 cancer deaths related to PCa are projected to occur in 2015.[2] Several factors, such as gradual implementation of prostate-specific antigen (PSA) screening, improved biopsy techniques and increasing westernized lifestyle, may partial explain this tendency.[2]