The Clinical Impact of Unilateral Versus Bilateral Invasion Into the Seminal Vesicle in Patients With Prostate Cancer Undergoing Radical Prostatectomy.

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.