The significance of microscopic bladder neck invasion in radical prostatectomies: pT4 disease?

Introduction: It is controversial whether microscopic invasion of the bladder neck (BN) has a high risk for biochemical progression following radical prostatectomy (RP). The tumor, node, and metastasis (TNM) classification for prostate cancer considers BN involvement to be pT4 disease, equivalent to rectal or external sphincter invasion, however, it does not specify whether the invasion is macroscopic or microscopic.

Materials And Methods: Clinicopathological findings were studied from 290 patients submitted to RP. The time to biochemical (prostate-specific antigen, PSA) progression-free outcome for patients with BN invasion was compared to patients with extraprostatic extension (EPE) or seminal vesicle invasion (SVI). A univariate Cox proportional hazards model was created and a final multivariate Cox proportional hazards model was developed to assess the influence of several variables simultaneously.

Results: BN invasion was present in 55/290 (18.96%) surgical specimens and 18/290 (6.2%) also showed positive surgical margins. Patients with microscopic BN invasion had significantly higher preoperative PSA, higher Gleason score, higher apical and circumferential positive surgical margins, more advanced pathological stage, and more extensive tumors. At 5 years 42%, 40%, and 27% of the patients with BN invasion, extraprostatic extension (EPE), and seminal vesicle invasion (SVI), respectively, were free of biochemical recurrence following RP. In multivariate analysis, BN invasion did not contribute for a higher relative hazard of PSA recurrence when added to EPE or SVI.

Conclusion: BN invasion is associated with adverse clinicopathological findings. However, the biochemical-free outcome following RP is similar to patients with EPE but significantly better than patients with SVI. The findings of this study do not favor considering microscopic bladder neck invasion as stage pT4 but, probably, stage pT3a.