The Clinical Significance of Either Extraprostatic Extension or Microscopic Bladder Neck Invasion Alone Versus Both in Men With pT3a Prostate Cancer Undergoing Radical Prostatectomy: A Proposal for a New pT3a Subclassification

Abstract

The prognosis of prostate cancers exhibiting extraprostatic extension [other than bladder or seminal vesicle invasion (EPE)] and/or microscopic bladder neck invasion (mBNI) is variable, and further risk stratification is required. We herein assessed radical prostatectomy findings and long-term oncologic outcomes in consecutive 957 patients with pT3a disease. The patient cohort was divided into 4 groups, focal EPE (F-EPE) only (n=177; 18.5%), nonfocal/established (E-EPE) only (n=634; 66.2%), mBNI only (n=51; 5.3%). The rate of positive surgical margin and estimated volume of tumor were significantly higher in patients with both EPE and mBNI than in those with either. In addition, compared with F-EPE or mBNI only, E-EPE only was significantly associated with higher Grade Group, lymph node metastasis, and larger tumor volume. Kaplan-Meier analysis revealed a comparable prognosis after prostatectomy between those showing F-EPE only versus mBNI only ( P =0.986), and these 2 cohorts were combined for further analysis. Then, patients showing E-EPE only had a significantly higher or lower risk of progression compared with those showing F-EPE or mBNI only ( P <0.001) or both EPE and mBNI ( P <0.001), respectively. These significant differences in progression-free survival were also seen in subgroups, including those with or without undergoing adjuvant therapy before recurrence and those showing no lymph node metastasis. In multivariate analysis, F-EPE or mBNI only (hazard ratio=0.524, P =0.003) or both EPE and mBNI (hazard ratio=1.465, P =0.039) (vs. E-EPE only) showed significance for progression. Based on these findings, we propose a novel pT3a subclassification, pT3a1 (F-EPE or mBNI alone), pT3a2 (E-EPE alone), and pT3a3 (both EPE and mBNI).