KLK3 and prostate cancer: Additionally, Spratt et al. retrospectively evaluated metformin as a radiosensitizer in prostate cancer and found there to be a survival benefit (improved prostate-specific antigen-recurrence-free survival, distant metastases-free survival, prostate cancer-specific mortality, and overall survival) and reduced development of castration-resistant prostate cancer in patients treated with EBRT while concurrently receiving metformin [16].