The Clinical Impact of pT3a Lesions in Patients With pT3b Prostate Cancer Undergoing Radical Prostatectomy

Seminal vesicle invasion (SVI) by prostate cancer (pT3b disease) has been considered as a key prognostic factor.To assess the clinical impact of T3a lesions (ie, extraprostatic extension other than bladder neck invasion [BNI] or SVI [EPE], microscopic bladder neck invasion [mBNI]) in pT3b disease.We compared radical prostatectomy findings and long-term oncologic outcomes in 248 patients with pT3b disease, with versus without EPE/mBNI.Extraprostatic extension/mBNI was found in 219 (88.3%)/48 (19.4%) cases, respectively. Extraprostatic extension was significantly associated with higher preoperative prostate-specific antigen (PSA) level, higher rates of positive surgical margin (pSM) and lymphovascular invasion (LVI), and larger tumor volume. Similarly, mBNI was significantly associated with higher PSA level, higher rates of Grade Group(s) 4-5 or 5, pSM, LVI, and pN1, and larger tumor volume. Significant differences in all of these clinicopathologic features (except lymph node metastasis) between EPE-/mBNI+ or EPE+/mBNI- and EPE+/mBNI+ cases were also observed. Outcome analysis revealed that patients with EPE (P < .001) or mBNI (P < .001) had a significantly higher risk of disease progression than respective controls. Notably, there were significant differences in progression-free survival between EPE-/mBNI+ or EPE+/mBNI- cases and EPE-/mBNI- (P = .001) or EPE+/mBNI+ (P < .001) cases. In multivariate analysis, EPE (hazard ratio [HR] = 6.53, P = .009) and mBNI (HR = 2.33, P = .003), as well as EPE-/mBNI+ or EPE+/mBNI- (HR = 11.7, P = .01) and EPE+/mBNI+ (HR = 25.9, P = .002) versus EPE-/mBNI-, showed significance for progression.From these significant findings, we propose a novel pT3b subclassification: pT3b1 (SVI alone without EPE or mBNI), pT3b2 (SVI with either EPE or mBNI), and pT3b3 (SVI with both EPE and mBNI).