Detection of occult metastasis in squamous cell carcinoma of the penis using a dynamic sentinel node procedure

PURPOSE: We evaluated the so-called dynamic sentinel node procedure in patients with penile cancer. This new staging technique consists of excisional biopsy of the first lymph node onto which a tumor drains the so-called sentinel node, based on individual mapping of lymphatic drainage. MATERIALS AND METHODS: From 1994 to 1998, 55 consecutive patients with stage T2 or greater bilateral or unilateral node negative squamous cell carcinoma of the penis were prospectively entered in this study. Tumor stage was T2N0 in 42, T2N1 in 4 and T3N0 in 9 cases. To locate the sentinel node each patient underwent lymphoscintigraphy with 99mtechnetium nanocolloid injected intradermally around the tumor. The following day the sentinel node was identified intraoperatively using patent blue dye injected intradermally around the tumor and a gamma detection probe. Regional lymph node dissection was restricted to patients with a tumor positive sentinel node only. RESULTS: Scintigraphy revealed 125 sentinel nodes in 107 inguinal regions, including no sentinel node in 2 patients, 1 or more unilateral nodes in 10 and bilateral drainage in 43. At surgery 108 sentinel nodes were removed. In 8 patients with 2 or more sentinel nodes on lymphoscintigraphy only 1 was noted intraoperatively and in 9 an additional sentinel node was removed, which was not identified by scintigraphy. All nodes were identified with the gamma detection probe. In 1 patient a wound abscess developed. Regional lymph node dissection was performed in 11 patients with sentinel node metastasis. Median followup was 22 months (range 4.1 to 61). In 1 patient lymph node metastasis was noted at followup despite prior excision of a tumor-free sentinel node. CONCLUSIONS: The dynamic sentinel node procedure is a promising staging technique to detect early metastatic dissemination of penile cancer based on individual mapping of lymphatic drainage, and enables identification of patients with clinically node negative disease requiring regional lymph node dissection.