Sentinel node biopsy for malignant melanoma - technical details and clinical results in 259 patients

The purpose of this paper was to present our 4-year experience with sentine l node biopsy in the treatment of malignant melanoma. We will present techn ical details that influence the efficacy of the procedure and discuss the c linical, therapeutic and prognostic advantages of this technique. A total o f 259 consecutive patients with primary skin melanoma (T2-3 N0 M0) underwen t sentinel node biopsy between March 1996 and May 2000. All patients underw ent previous excisional biopsy of the primary lesion and clinical and radio graphic examination to exclude lymphatic or systemic macroscopic spread of the disease. Preoperative lymphoscintigraphy (Tc-99m-nanocoll) was routinel y performed in the last 184 patients. Intraoperative detection of the senti nel node was performed by perilesional, intradermal injection of blue dye a ssociated with a gamma probe (Neoprobe 2000) in the last 141 patients. For each anatomical site of dissection (inguinal, axillary, head and neck), det ection rates with or without gamma probe were compared, focusing on the mai n reasons for failure. Sentinel nodes, serially sectioned, were all hematox ylin-eosin and immunohistochemically stained. All patients positive for mic rometastasis underwent radical Lymphadenectomy. Comparative analysis was pe rformed between the incidence of metastasis in sentinel and non-sentinel no des, according to the clinical stage of the disease. The overall detection rate of sentinel nodes was 96%. Relevant differences were found according t o the site of dissection and the use of a gamma probe. The gamma probe make s the procedure more effective, less invasive, and less expensive. Timing a nd accuracy of the preoperative lymphoscintigraphy are basic steps in the p rocedure. The overall incidence of positive sentinel node was 14.6% with di fferences correlated with thickness of primary lesion (0.75-1.5 mm: 7.3%; 1 .5-3 mm: 14.9%; 3-4 mm: 30.5%). Metastasis in other non-sentinel nodes was found only with primary tumor thickness exceeding 2 mm. Correlation between sentinel node metastasis and prognosis as well as adjuvant therapy will be discussed. Sentinel node biopsy is a procedure requiring a multidisciplina ry approach (surgery, nuclear medicine, and pathology). A specific learning phase (>30 patients) is recommended for reliable results. An improvement i n survival rates by sentinel node biopsy has not yet been demonstrated, but this more accurate N-staging procedure offers clear advantages in terms of the patient's quality of life, prognosis, and indication for adjuvant ther apy.