Urothelial carcinoma can involve the prostate by extension from bladder cancer or, rarely, as a primary tumour. It is almost always tied to bladder urothelial cancer — particularly carcinoma in situ — and the depth of prostatic involvement drives both treatment and prognosis.
Background and Risk Factors
- 90% of prostatic urothelial carcinomas occur in men with a history of bladder urothelial cancer (chiefly bladder CIS), yet only 3% of men with primary bladder urothelial cancer go on to develop it.
- 40% of men undergoing radical cystectomy for urothelial cancer are found to have urothelial carcinoma of the prostate.
- Primary urothelial carcinoma of the prostate without bladder involvement is uncommon (1–4% of all prostate carcinomas).
- Spread is usually by direct extension of bladder cancer into the prostatic urethra, though pagetoid spread beneath normal-appearing urothelium also occurs; intraductal and infiltrating disease accompanies higher-stage bladder tumours.
Five risk factors for prostatic urethral involvement: bladder CIS, previous intravesical chemotherapy, multifocal disease, tumours at the trigone or bladder neck, and high-risk NMIBC.
Staging (AJCC 8th Edition, Prostatic Urethra)
| Stage | Definition |
|---|---|
| Ta | Non-invasive papillary carcinoma |
| Tis | Carcinoma in situ — Tis pu (prostatic urethra) or Tis pd (prostatic ducts) |
| T1 | Invasion of subepithelial connective tissue |
| T2 | Invasion of prostatic stroma |
| T3 | Invasion of periprostatic fat or bladder neck (extraprostatic extension) |
| T4 | Invasion of adjacent organs (e.g. bladder or rectal wall) |
Importantly, in the bladder cancer staging system only prostatic stromal invasion (direct or indirect) qualifies as T4a bladder cancer; extension into the prostatic urethra without stromal invasion is staged under the urethra, not the bladder, and does not carry an adverse prognosis. (For reference, penile-urethra T-stages run T1 subepithelial connective tissue → T2 corpus spongiosum → T3 corpus cavernosum → T4 adjacent organs.)
Diagnosis
Transurethral resection and biopsy of the prostatic urethra is the primary detection method. For the highest yield, biopsy any suspicious area plus the 5 and 7 o'clock (precollicular) positions at the verumontanum, where prostatic ducts are most concentrated. Indications include positive urine cytology with a negative bladder biopsy, recurrent bladder cancer after multiple courses of intravesical chemotherapy, and a visible prostatic-urethral tumour.
Management
Treatment follows the depth of involvement:
- CIS of the prostatic urethra (Tis pu) or a visible prostatic-urethral tumour with concurrent NMIBC — TURP then BCG (TURP first for accurate staging and to increase BCG efficacy by exposing more surface area).
- CIS of the prostatic ducts (Tis pd) — controversial; consider TURP + BCG with re-biopsy after BCG, because ductal disease can invade and, once invasive, carries a high metastatic risk.
- Recurrent high-grade disease after TURP + BCG — consider radical cystectomy + urethrectomy; for a bladder-sparing approach, repeat BCG or intravesical gemcitabine.
- Prostatic stromal invasion (T2) — radical cystectomy ± urethrectomy (urethrectomy especially if tumour is at or near the margin); stromal invasion is a poor prognostic factor, treated with multimodal chemotherapy plus radical cystectomy.
Prognosis
Five-year survival varies sharply with depth: up to 100% with urethral mucosal involvement, 50% with ductal/acinar/glandular involvement, and 40% with stromal invasion.
Self-Test
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What are the risk factors for urothelial carcinoma of the prostate? Bladder CIS, previous intravesical chemotherapy, multifocal disease, tumours at the trigone or bladder neck, and high-risk NMIBC.
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How is bladder cancer invading the prostatic stroma staged? pT4a.