Comparison of the diagnostic efficacy and perioperative outcomes of limited versus extended pelvic lymphadenectomy during robot-assisted radical prostatectomy: a multi-institutional retrospective study in Japan

Background: We conducted a retrospective study to compare the perioperative course and lymph node (LN) counts of patients undergoing limited pelvic lymphadenectomy (lPLND) or extended pelvic lymphadenectomy (ePLND) during robot-assisted radical prostatectomy in an initial Japanese series. Methods: The cohort included 1333 patients who underwent either lPLND (n = 902) or ePLND (n = 431) during robot-assisted radical prostatectomy at five institutions in Japan. All complications within 28 days of surgery were recorded, and clinical data were collected retrospectively. The outcomes and complications were compared relative to the extent of lymphadenectomy, and we conducted univariate and multivariate logistic regression analyses to assess the predictors of the major complications. Results: On multivariate analysis for evaluating the associations between major complications and perioperative characteristics, console time (p = 0.001) was significantly associated with major complications, although the extent of lymphadenectomy (p = 0.272) was not significantly associated with major complications. In the distribution of positive LNs removed in the extended pelvic lymphadenectomy cohort, 60.4% of patients had positive LNs only in the obturator/internal iliac region. However, 22.6% of the patients with positive LNs had no positive LNs in the obturator/internal iliac region, but only in the external/common iliac region. Conclusions: ePLND, which significantly increased the console time and blood loss but nearly quadrupled the lymph node yield, is considered a relatively safe and acceptable procedure. Moreover, the results of this study suggest that ePLND improves staging and removes a greater number of metastatic nodes.