Context.—: Seminal vesicle involvement by prostate cancer has generally been considered as a key prognosticator.
Objective.—: To assess the clinical significance of unilateral (Uni) versus bilateral (Bil) seminal vesicle invasion (SVI).
Design.—: We compared radical prostatectomy findings and long-term oncologic outcomes in 248 patients showing Uni-SVI (n = 139) versus Bil-SVI (n = 109).
Results.—: Tumor grade was significantly higher in Bil-SVI cases than in Uni-SVI cases. Additionally, Bil-SVI was significantly associated with a higher incidence of lymphovascular invasion, lymph node metastasis, or positive surgical margin, and larger estimated tumor volume. When the histopathologic features at SVI foci were compared, Grade Group (GG) 3-5/4-5/5 and cribriform morphology were significantly more often seen in Bil-SVI. Outcome analysis revealed that patients with Bil-SVI had a significantly higher risk of disease progression (P < .001) than patients with Uni-SVI. Significantly worse progression-free survival in patients with Bil-SVI was also observed in all subgroups examined, including those with no immediate adjuvant therapy (IAT) (n = 139; P = .01), IAT (n = 109; P = .001), pN0 disease (n = 153; P = .002), or pN1 disease (n = 93; P = .006). In multivariate analysis, Bil-SVI (versus Uni-SVI) showed significance for progression in the entire (hazard ratio [HR] = 1.83, P = .01), IAT (HR = 2.90, P = .006), and pN0 (HR = 2.05, P = .01) cohorts. Meanwhile, tumor grade at SVI (eg, GG4, GG5), as an independent predictor, was significantly associated with patient outcomes.
Conclusions.—: Bil-SVI was found to be strongly associated with worse histopathologic features on radical prostatectomy and poorer prognosis. Pathologists may thus need to report Uni-SVI versus Bil-SVI, along with other histopathologic findings, such as Gleason score, at SVI in prostatectomy specimens.