Purpose: The purpose of this study was to determine the potential role of the sentinel lymph node (SLN) procedure in limited lymph node dissection in patients with apparently localised prostate carcinoma.
Methods: In 27 patients with organ-confined prostate cancer, a single injection of 0.3 ml/30 MBq( 99m)Tc-rhenium sulphur colloid was injected transrectally into the peripheral zone of each lobe of the prostate (total 0.6 ml/60 MBq) under ultrasound guidance. Two hours after injection, scintigraphy was performed. The first step in surgery was the detection and dissection of lymph nodes identified as SLNs. Then, standard lymphadenectomy was performed, consisting in a limited dissection that included all lymph nodes from the obturator fossa and along the external iliac vein. Lymphatic tissue along the hypogastric artery was not systematically removed, except in the presence of SLNs.
Results: Mean patient age was 66 years (48-77); the mean serum prostate-specific antigen value was 10.6 ng/ml. In a high proportion of patients (21/27, 77.8%) an SLN was located along the initial centimetres of the hypogastric artery. The second most frequent site of SLNs was in the obturator fossa (11/27 patients, 40.7%), followed by the external iliac area (5/27 patients, 18.5%). Four patients had lymph node metastases, all in SLNs: two in the hypogastric area and two in the obturator fossa.
Conclusion: The SLN procedure revealed the individual variability in the lymphatic drainage of the prostate. The main site of SLNs was the hypogastric area, and two of the four metastatic nodes were located at this site. A limited standard pelvic lymphadenectomy, excluding the hypogastric lymph nodes, would have missed half of the lymph node metastases in this study. A radionuclide SLN procedure could assist in the correct staging of patients with early prostate cancer, especially when performing limited lymphadenectomy.