Oncologic impact of en bloc seminal vesicle excision in robot-assisted radical prostatectomy for T3b prostate cancer

Background: The oncological benefit of en bloc seminal vesicle excision (EB-SVE) in T3b prostate cancer remains unestablished. We aimed to evaluate the impact of EB-SVE on histopathological outcomes and short-term clinical results in pT3b prostate cancer, compared to conventional SVE (C-SVE). Methods: We retrospectively reviewed 351 patients who underwent robotic radical prostatectomy by a single surgeon between July 2020 and December 2024. Among them, 75 patients were identified with pT3b prostate cancer. EB-SVE involves extensive removal of tissue surrounding the seminal vesicles (SVs) without direct handling or damaging them during excision. This technique was performed in cases with a preoperative suspicion of SV invasion. Conversely, C-SVE was performed in cases without such suspicion. We compared histopathological findings and short-term clinical outcomes between the EB-SVE and C-SVE groups. Results: A total of 66 patients were eligible for analysis. EB-SVE was performed unilaterally in 16 patients and bilaterally in 23 patients, while 27 patients underwent C-SVE. Among the 132 SV units (two per patient), 94 showed cancer involvement. Peri-SV tissue invasion was more frequently observed in the EB-SVE group than in the C-SVE group (87.5% vs. 52.6%, P = 0.001). However, positive surgical margins (PSMs) in peri-SV tissue occurred in only 1 SV unit (1.8%) with EB-SVE, compared to 6 SV units (15.8%) with C-SVE ( P = 0.023). Among 33 pT3b/pN0 patients, peri-SV PSM independently predicted prostate-specific antigen persistence ( P = 0.038). Conclusions: En bloc excision of peri-SV tissue via EB-SVE may reduce peri-SV PSM rates and improve short-term oncological outcomes in pT3b prostate cancer.