Laparoscopic radioisotope-guided sentinel lymph node dissection in staging of prostate cancer

To present our experience in laparoscopic sentinel lymph node (SLN) dissection in staging of clinically localized prostate cancer.

From November 2001 to January 2005 laparoscopic SLN dissection was performed in 140 patients with clinically localized prostate cancer preceding radical prostatectomy. Mean preoperative prostate-specific antigen (PSA) level was 8.26 ng/ml (SD 9.46). At 24 h before surgery, 2 ml 99mTc-labeled human albumin (2 ml/200 MBq) colloid was injected into the prostate gland under transrectal ultrasound guidance. Prostatic SLNs were detected by preoperative planar scintigraphy and intraoperative scanning with a specially designed laparoscopic gamma probe. The detected nodes were dissected and evaluated on frozen section. In case of positive frozen section extended lymph node dissection was performed.

SLN was identified on both or one pelvic sidewall in 96 (68.1%) and 36 (25.7%) of the patients, respectively. SLNs were undetectable in 8 (5.7%) cases. In 48.2% (135 of 280) of the pelvic sidewalls, SLNs were exclusively outside the obturator fossa. Final histopathologic examination revealed SLN metastases in 19 (13.5%) patients; 71.4% (20 of 28) of the detected metastases were outside the current standard of lymph node dissection limited to the obturator fossa. Mean tumor size was 2.3 mm (SD 1.7).

Our data confirm the reliability of laparoscopic SLN dissection in staging of prostate cancer. Significant numbers of detected metastases were outside of the routinely sampled obturator fossa. Small metastasis size makes them undetectable by currently available preoperative imaging modalities.