Efficacy of transrectal ultrasound-guided seminal vesicle biopsies in the detection of seminal vesicle invasion by prostate cancer.

Detection of microscopic seminal vesicle invasion with prostate cancer by transrectal ultrasound-guided seminal vesicle biopsies provides a method of evaluation that is much less subjective than digital rectal examination or imaging techniques. The accuracy of seminal vesicle biopsy is analyzed in 73 patients undergoing transrectal ultrasound-guided biopsy of 145 seminal vesicles followed by radical prostatectomy. Of 133 benign seminal vesicle biopsies 11 (8.3%) were found in the surgical specimen to have cancer involving an average of 6% of the seminal vesicle area. Of 8 seminal vesicle biopsies showing cancer adjacent to seminal vesicle epithelium 100% demonstrated seminal vesicle invasion in the surgical specimen extending for an average of 19% of the seminal vesicle area. Three biopsies exhibited cancer but no seminal vesicle epithelium; only 1 (33%) of these had seminal vesicle invasion for 5% of the seminal vesicle area. One biopsy revealed normal prostate tissue. Careful placement of bilateral biopsy sites cephalad to the prostate base (not traversing any portion of the prostate gland) is recommended. Caution should be exercised when basing treatment decisions on seminal vesicle biopsies that do not reveal seminal vesicle epithelium histologically.