Prognostic Impact of Seminal Vesicle Mucosal Invasion in pT3b Prostate Cancer Following Radical Prostatectomy

Purpose: The extent of seminal vesicle invasion (SVI) in prostate cancer can be classified into muscle layer invasion (SVI-muscle) and mucosal layer invasion (SVI-mucosa). This study aimed to evaluate the prognostic significance of the extent of SVI after radical prostatectomy.Materials and Methods: SVI-mucosa data were prospectively collected since 2014. Among 1,659 radical prostatectomy specimens from 2014 to 2023, 259 cases (15.6%) with extraprostatic SVI were enrolled. A total of 252 cases with available follow-up data were included in the final analysis.Results: SVI-mucosa was identified in 63 cases (25.0%), and SVI-muscle was identified in all 252 cases. Extracapsular extension was present in nearly all SVI cases (99.6%). The mean tumor volume percentage in final specimens was significantly higher in patients with SVI-mucosa (50%) compared to those without it (35%) (p<0.001). A high Gleason score (≥8) was more common in men with SVI-mucosa (p=0.021). Only 10 (5.3%) and 4 patients (6.3%) with and without SVI-mucosa, respectively, received adjuvant therapy (p=0.544). Biochemical recurrence-free survival did not significantly differ between men with SVI-mucosa and those with SVI-muscle alone (log-rank test, p=0.309). The 5-year metastasis-free survival and prostate cancerspecific survival rates were 86.0% vs. 91.6% (p=0.654) and 99.5% vs. 100% (p=0.865) in patients with and without SVI-mucosa, respectively.Conclusion: The prognosis of patients with SVI is not uniformly poor. SVI-mucosa was associated with more aggressive pathological features. In most cases, SVI-muscle appears to develop first following extracapsular extension, with subsequent progression to SVI-mucosa. However, the presence of SVI-mucosa, an advanced status of SVI, did not significantly impact biochemical recurrence and metastasis-free survival rates.