One cannot tell for certain. The doctor is guided by the findings on digital rectal examination, trans-rectal ultrasonography performed in conjunction with the biopsy, abdominal-pelvic CT or MRI scan, bone scan, PSA level, Gleason grade, and amount of cancer present in the biopsy cores. Taken together, and sometimes used in tables or nomograms, they provide a fairly accurate estimate of whether the tumor is confined.