Should we reconsider the indications for ileo-obturator node dissection with localized prostate cancer?

To evaluate the need for ileo-obturator node dissection in patients with localized prostate cancer who are undergoing radical retropubic prostatectomy.

Over a 5-year-period, 95 patients underwent bilateral pelvic lymphadenectomy. Ninety were performed in association with planned radical prostatectomy and five were staging procedures in clinical stage T3 patients prior to radiotherapy or hormonal therapy. The patients with localized prostate cancer were stage T1a (one patient), T1b (21), T2a (30), and T2b (38). Pre-operative biopsies in the patients with localized cancer were well differentiated in 44 patients, moderately well differentiated in 45 and poorly differentiated in one. In the patients with T3 tumours, pre-operative biopsies were well differentiated in one, moderately well differentiated in two and poorly differentiated in two. Prostate-specific antigen (PSA) levels ranged from 0.4 to 110.1 ng/mL (Hybritech assay).

Two patients had positive lymph node dissections on fixed section. These two patients had well-differentiated T1b disease with a PSA level of 72.4 ng/mL and poorly differentiated T3 disease with a PSA level of 58.5 ng/mL. There was significant upstaging (P < 0.001) and upgrading (P < 0.001) on pathological examination. None of the 71 patients with a PSA < or = 10 ng/mL had positive lymph nodes compared with 8.3% of the 24 patients with a PSA > 10 ng/mL (P = 0.0618). Lymph node metastases were present in 1% of patients with well or moderately well-differentiated prostate cancer on pre-operative biopsy versus 33% with poorly differentiated disease (P = 0.0625). These P values strongly suggest an association, achieving significance only at the 10% level which might be the more appropriate level given the relative lack of power of the study due to the small number of patients with positive lymph nodes.

These results suggest that routine ileo-obturator node dissection in patients with well or moderately well-differentiated, localized prostate cancer and a PSA level < 10 ng/mL may be unnecessary, especially as a separate procedure.