Cancer is found in the prostate only. The cancer (1) is found by needle biopsy or in a small amount of tissue during surgery for other reasons; the prostate-specific antigen (PSA) level is lower than 10 and the Gleason score is 6 or lower; or (2) is found in one-half or less of one lobe of the prostate; the PSA level is lower than 10 and the Gleason score is 6 or lower; or (3) cannot be felt during a digital rectal exam and is not visible by imaging; cancer is found in one-half or less of one lobe of the prostate and the PSA level and Gleason score are not known.