Assessment of lymph node yield after pelvic lymph node dissection in men with prostate cancer: a comparison between robot-assisted radical prostatectomy and open radical prostatectomy in the modern era.
Objective: Studies of radical prostatectomy (RP) suggest that higher lymph node yield (LNY) improves tumor staging. Robot-assisted radical prostatectomy (RARP) is becoming increasingly popular, yet LNY data are not well reported. We compare LNY from contemporary open RP (ORP) with RARP at an academic center.
Methods: A retrospective study was conducted of an Urologic Oncology Database. Between January 2005 and November 2009, 217 men underwent ORP with pelvic lymph node dissection (PLND); 99 underwent RARP with PLND by a single surgeon during the same period. Men were stratified according to the D'Amico risk criteria. For intermediate and high-risk disease, an extended PLND was performed. Patient demographic, operative, and pathologic variables were measured, and LNY was compared across groups.
Results: No significant differences were seen between groups for race, body mass index, preoperative prostate-specific antigen level or biopsy Gleason score. Patients were younger for RARP vs ORP (P = 0.003) and had higher clinical tumor stage (P = 0.02). Operative time was longer (P = 0.03) and estimated blood loss was greater (P < 0.001) in the ORP group. Overall, only a borderline significant difference was seen in LNY between ORP and RARP (7.49 vs 6.35 nodes, respectively, P = 0.06). No difference was seen for intermediate and high-risk patients, with 7.7 vs 6.8 nodes for ORP and RARP, respectively (P = 0.27). The lymph node metastasis rate was 6.3%, with more positive nodes detected during ORP vs RARP: 19/217 (8.8%) vs 1/99 (1.0%), P = 0.009.
Conclusions: No significant differences were seen in LNY during RARP and ORP for intermediate and high-risk men. For experienced surgeons, RARP can achieve equivalent LNY as ORP. A future study with a larger sample size is necessary to make a definitive statement of equivalence.