Anatomical basis for pelvic lymphadenectomy in prostate cancer: results of an autopsy study and implications for the clinic.

PURPOSE: Pelvic lymphadenectomy remains the most reliable method to prove lymph node metastases in prostate cancer. However, evaluation of lymphadenectomy to be complete and sufficient as judged by the number of removed lymph nodes in hampered by the fact that, in contrast to other malignancies (for example breast or gastric cancer), anatomical studies investigating the regular and average number of pelvic lymph nodes are missing. We established an anatomically based standard for pelvic lymphadenectomy.
MATERIALS AND METHODS: Standard pelvic lymphadenectomy was performed on 30 human cadavers and 59 consecutive patients with clinically organ confined prostate cancer during radical retropubic prostatectomy. Number, size and topography of the lymph nodes were noted separately for each anatomical region of both iliac fossas.
RESULTS: The mean number of lymph nodes removed in the autopsy series plus or minus standard deviation (22.7 +/- 10.2, range 8 to 56) was nearly identical to that from patients with prostate cancer (20.5 +/- 6.6, range 10 to 37) but striking interindividual differences were observed. Patients with prostate cancer demonstrated enlarged nodes regardless of whether they did or did not contain tumor. Interestingly, pelvic lymph node metastases were more common on the left side regardless of the primary tumor site.
CONCLUSIONS: Approximately 20 pelvic lymph nodes may serve as a guideline for a sufficient standard pelvic lymph node dissection. Lymphadenopathy in prostate cancer patients is not always a result of metastases but, rather, hyperplastic or regressive alterations. A preferential distribution of lymph node metastases along the left iliac vessels regardless of the primary tumor site in the prostate warrants further investigation.