The Clinical Significance of pT3a Lesions as Well as Unilateral Versus Bilateral Invasion Into the Seminal Vesicle in Men With pT3b Prostate Cancer

center dot Context.-Seminal vesicle invasion (SVI) as pT3b prostate cancer generally, but not uniformly, indicates poor prognosis.Objective.-To determine the clinical impact of pT3a lesions (ie, extraprostatic extension other than seminal vesicle or bladder invasion [EPE], microscopic bladder neck invasion [mBNI]), as well as unilateral (Uni) versus bilateral (Bil) SVI in pT3b disease.Design.-We assessed radical prostatectomy findings and long-term oncologic outcomes in 248 consecutive patients with pT3b disease.Results.-Focal EPE, nonfocal EPE, mBNI, Uni-SVI, and Bil-SVI were identified in 13 (5.2%), 206 (83.1%), 48 (19.4%), 109 (44.0%), and 139 (56.0%) cases, respectively. Of possible combinations, we eventually divided our cases into 3 cohorts-Group 1: Uni/Bil-SVI and EPE-/ mBNI- (n = 28; 11.3%); Group 2: Uni-SVI and EPE or mBNI (n = 103; 41.5%); and Group 3: Bil-SVI and EPE or mBNI (n = 70; 28.2%) or Uni/Bil-SVI and EPE+/mBNI+ (n = 47; 19.0%). Group 3 patients showed significant adverse histopathologic findings, compared with Group 1 or Group 2 patients. Kaplan-Meier analysis revealed that the prognosis was worse in the following order: Group 1, Group 2, and Group 3; and the differences in progression free survival between any 2 groups were statistically significant. These significant differences were also seen in subgroups, such as those without or with adjuvant therapy before recurrence and those without lymph node metastasis. Additionally, Group 3 patients had a significantly higher risk of cancer-specific mortality than Group 2 patients. In multivariate analysis (Group 2 as a reference), Group 1 (hazard ratio [HR] = 0.169, P = .01) and Group 3 (HR = 1.620, P = .04) showed significance for progression.Conclusions.-From these significant findings, we propose a novel pT3b subclassification, namely pT3b1 (Group 1), pT3b2 (Group 2), and pT3b3 (Group 3), which more accurately stratifies its prognosis.