Mechanisms of prostatic stromal invasion in patients with bladder cancer: clinical significance.

PURPOSE: We assess the pathological mechanisms of silent prostatic stromal invasion in patients with bladder cancer for early detection and treatment.
MATERIALS AND METHODS: Between August 1998 and January 1999, 10 patients with clinically organ confined transitional cell carcinoma of the bladder and known prostatic stromal invasion on transurethral biopsy or who were high risk for prostatic involvement due to tumor location near the bladder neck were studied for histological patterns of prostatic invasion. There were 5 cystectomy specimens distended for 24 hours with formalin via a Foley catheter, then step sectioned longitudinally at 3 mm. intervals through the bladder neck and prostate. Standard hematoxylin and eosin staining methods were used and sections were analyzed by 2 pathologists.
RESULTS: There were 3 separate patterns of prostatic stromal invasion elucidated, including 2 previously described methods of extravesical or intraurethral invasion into the prostatic stroma and a third one through the bladder neck directly into the prostatic stroma. The third pattern was not grossly evident on endoscopy or urethral biopsy before cystectomy.
CONCLUSIONS: Longitudinal sectioning of the bladder neck and prostate of cystectomy specimens suggests tumors at the bladder neck may directly invade the prostatic stroma without histological evidence of extravesical or intraurethral spread. Such direct silent tumor invasion of the prostate by superficial or endoscopically inapparent tumor is difficult to detect clinically by current biopsy methods. New methods of detection are necessary.