17 CRITICAL RE-EVALUATION OF A MODIFIED SENTINEL GUIDED PELVIC LYMPH NODE RESECTION IN PROSTATE CARCINOMA: REVIEW OF 401 CONSECUTIVE CASES

Abstract

INTRODUCTION AND OBJECTIVE: Lymph node dissection during radical prostatectomy for prostate cancer remains a disputed area. Radioisotope-guided pelvic lymph node dissection has been shown to provide a better sensitivity in detecting lymph node metastases compared to standard lymphadenectomy of the obturatory region. Goal of this study was to use our data to re-evaluate the method of intraoperative sentinel lymph node (SLN) mapping with a gamma probe for detecting lymph node metastases. METHODS: 401 patients with prostate cancer (median age 64 years, median Gleason score 7, median PSA value 8 ng/dl) underwent SLN-dissection either as an isolated laparoscopic staging procedure (41 patients) or during open retropubic prostatectomy (360 patients). 16 to 24 hours before surgery a transrectal ultrasound guided injection of 99mTc nanocolloid was performed. During surgery, routinely the lymph nodes in the obturator fossa were dissected, and in addition, remaining SLNs were identified with the help of intraoperative gamma probing and subsequently removed. RESULTS: 25 (6,2%) of 401 patients showed lymph node metastases. In these 25 patients a total of 501 lymph nodes were dissected (median 17). 51 of the removed lymph nodes exhibited metastases. Positive lymph nodes in the obturatory region were found in 16 (64.0%) patients, from which 3 showed additional positive lymph nodes in other regions. 9 (36.0%) patients had metastatic lymph nodes which were located exclusively outside the obturator fossa. These metastases displayed the following distribution: 6x in the internal iliac region, 2x in the common iliac region and 1x in the external iliac region. Complications occurring in the 401 patients were 8 (2.0%) lymphoceles which needed further intervention, 3 (0.7%) ureteric injuries and 1 (0.2%) prostatitis after transrectal injection of 99mTc nanocolloid. CONCLUSIONS: The present data demonstrates the efficacy of this method. Intraoperative SLN gamma probing increases the rate of detected lymph node metastases compared with standard lymph adenectomy of the obturator fossa. We found 9 out of 401 additional patients that would not have been detected by standard dissection of the obturatory region. At the same time we achieved a low complication rate. SLN-resection can be seen as an important tool for an exact prostate cancer staging, and might help to reduce the morbidity compared to extended field lymph node resection without reducing the sensitivity.