About 6% of prostatic biopsies show PIN (prostatic intraepithelial neoplasia) or atypia (atypical hyperplasia). Prostate cancer is caused by changes (mutations) in the DNA that affect the regulation of the growth of normal prostate cells. It is probable that several mutations (at least 5 or 6) have to occur before a full-blown cancer occurs. These mutations may accumulate over time, causing the gradual progression to prostate cancer. It is likely that certain mutations may cause a precancerous condition, PIN. PIN is also found as a satellite lesion surrounding a prostate cancer or elsewhere in a cancerous prostate gland. Approximately 25% to 50% of men who have an elevated PSA level and high-grade PIN are subsequently found to have prostate cancer within four years. Accordingly, repeat biopsies are routinely recommended in men with PIN. Recent studies show that the risk for finding cancer after findings of PIN is less than previously thought, especially with extended biopsies (taking 12 or more samples) being performed. However, the information is still incomplete on the long-term risk for prostate cancer in men with high-grade PIN.