Comparison of semi-extended and standard lymph node dissection in radical prostatectomy: A single-institute experience.

Standard lymphadenectomy for prostate cancer is limited to the obturator lymph nodes (LNs), although the internal and external iliac LNs represent the primary landing zone for prostatic lymphatic drainage. We performed anatomically semi-extended pelvic lymph node dissection (PLND) to assess the incidence of LN metastasis in cases of clinically localized prostate cancer. A total of 730 consecutive patients underwent radical prostatectomy with either semi-extended PLND, comprising 6 selective fields, namely the external iliac, internal iliac and obturator LNs bilaterally, or standard LND (obturator LNs alone). A total of 131 patients undergoing semi-extended PLND were compared with 599 patients undergoing standard LND. The patients were stratified into high-risk [prostate-specific antigen (PSA)>20 ng/ml, Gleason score (GS)≥8], intermediate-risk (PSA 10-20 ng/ml, GS=4+3) and low-risk (PSA<10 ng/ml, GS≤3+4) subgroups. Following semi-extended LND, positive LNs were detected in 12/61 (20%) of the high-risk, 1/30 (3%) of the intermediate-risk and 0/40 (0%) of the low-risk cases. Following standard LND, positive LNs were detected in 13/182 (7%) of the high-risk, 1/164 (0.6%) of the intermediate-risk and 0/253 (0%) of the low-risk cases. In high-risk patients, the detection rate of LN metastasis was significantly higher following extended LND compared with standard LND (P<0.01). In 9 of 13 patients (69%), metastases were identified in the internal and external iliac regions, despite negative obturator LNs. There were no significant differences regarding intraoperative and postoperative complications or blood loss in the two groups. There was no lymphocele formation in patients undergoing either standard or semi-extended LND. Extended pelvic LND (PLND) is associated with a high rate of LN metastasis detection outside the fields of standard LND in cases with clinically localized prostate cancer. Therefore, LND including the internal and external iliac LNs should be performed in all patients with high-risk prostate cancer; however, in the low-risk group, PLND may be omitted.