Transrectal ultrasound approach for identification and radioguided biopsy of sentinel node in lymph node staging of localized prostate cancer.

INTRODUCTION

The limited pelvic lymphadenectomy (LPL) is currently considered the referred method of identification of nodal micrometastases in localized prostate cancer. Lymphoscintigraphy (LS) and radioguided sentinel node biopsy (RSNB) could be an alternative method of nodal staging.

MATERIALS AND METHODS

Between June 2003 and February 2007 19 patients with prostate cancer without metastases were included in the study. Mean age was 66 years, mean PSA 15.51 ng/ml, Gleason score > 6. A transrectal ultrasound was performed with intraprostatic administration of 0.2 ml/190 MBq 99 mTc bound to nanocolloid particles, prepared the day before surgery. Dynamic and static scans of the pelvis were obtained at 30', 60' and 120' after injection. Hot spots outside the site of administration were considered as sentinel nodes (SLNs). Prior to prostatectomy, LPL was performed. The presence of a labeled node after LPL, identified by a gamma probe slided slowly down the chain of lymphatic drainage, was indication for an LPE.

RESULTS

A sentinel node was identified in 17/19 patients with preoperative lymphoscintigraphy (identification rate 89%) and in 16/19 patients during surgery (84%) with a negative predictive value of 97%. The most frequent site was identified at the level of hypogastric lymph nodes (56%), outside the standard of limited pelvic lymphadenectomy, followed by external iliac (33%), obturator (7%) and common iliac (4%) lymph nodes. Lymph node metastases were detected by histological examination in 2 patients (13%); total metastatic nodes found were 9: one in the first, and 8 in the second patient. Two metastatic nodes (22%) not removed by the limited pelvic lymphadenectomy were found with the sentinel lymph node dissection.

CONCLUSIONS

Ultrasound approach for lymphoscintigraphy and sentinel node identification, is a valuable tool in the staging of localized prostate cancer.