The Facts of Prostate Cancer 2/3 of men over age 50 have low grade tumors or potential cancer cells in their prostate. Only 10% will develop clinically aggressive prostate cancer. These non-invasive exams tell if a tumor is aggressive or not with an accuracy exceeding traditional biopsy results and correlate well with prognosis according to the latest international cancer conferences. The PSA test has a poor correlation with cancer detection. The digital rectal exam is more accurate in detecting high grade tumors than the PSA level. Biopsies are random, invasive and may spread tumor cells. New non-invasive treatments are guided by advanced radiologic imaging technologies. The therapeutic effect is serially studied by MRI and 3-D sonography. While generally successful, interval exams may document an unsatisfactory response, allowing ""standard"" treatments to be started, if necessary, in a timely manner.