Seminal vesicle volume as a sonographic predictor of prostate cancer stage

Accurate clinical staging of prostate cancer continues to challenge the urologist, with understaging a common problem. Preoperative identification of men with capsular penetration or seminal vesicle invasion would allow deferment of radical surgery unlikely to cure the patient. We investigated the ability of seminal vesicle volume as determined by transrectal ultrasound (TRUS) to predict the stage of prostate carcinoma.

Forty-seven consecutive men undergoing radical prostatectomy had preoperative determination of the seminal vesicle volume by TRUS. The volume was determined for each individual seminal vesicle as well as the total seminal vesicle volume. Asymmetry was defined as one seminal vesicle having twice the volume of the other.

Average total seminal vesicle volume was statistically greater for patients with Stage C disease as opposed to those with organ-confined tumors. Seminal vesicle asymmetry was also present statistically more often in Stage C patients than Stage B men. The combination of total seminal vesicle volume less than 15 cc and symmetrical seminal vesicles yielded a possibility of only 18% of extraprostatic extension of tumor.

We believe that seminal vesicle volume as determined by TRUS can aid in the staging of adenocarcinoma of the prostate and should be considered along with other parameters, such as prostate-specific antigen, acid phosphatase, and Gleason score, when planning therapy for this disease.