[Rectal involvement by prostate carcinoma: a report of three cases].

We reported 3 cases of rectal involvement by locally invasive prostate carcinoma which caused an urethrorectal fistula in case 1 and a rectal stenosis in case 2 and 3. Discriminating between primary rectal carcinoma and prostate carcinoma locally invasive to the rectum is very important because of distinct differences in treatment and prognosis. To confirm the tumor origin, tumor markers, proctosigmoidscopy, computerized tomography and biopsy with immunohistochemical staining for prostate specific antigen were useful.