Sentinel node biopsy has proven its value in a number of cancers, including in clinically node-negative melanoma of the head and neck region. However, experts agree that it remains unclear what role sentinel node biopsy should have in other head and neck cancers. Clinical trials are under way to clarify the issue.
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July 2007Sentinel Node Biopsy in Melanoma
Sentinel node biopsy was initially developed by Donald L. Morton, MD, Chief of the Melanoma Program and Medical Director and Surgeon-in-Chief of the John Wayne Cancer Institute in Santa Monica, CA, and colleagues in the early 1990s. The goal of the procedure is to improve staging of clinically node-negative patients by identifying small metastases in the first lymph node or nodes to which the tumor drains. For tumor types, such as melanoma, that metastasize via the lymphatic system, a negative sentinel node should indicate that the tumor has not spread beyond the initial tumor bed and that all nodes in the nearby basin will be negative. By more effectively identifying patients who have early nodal metastases, the procedure also reduces the number of patients who have to undergo a complete lymphadenectomy.
Results from a large multinational randomized trial indicate that sentinel node biopsy prolongs disease-free survival in patients with intermediate-thickness clinically node-negative melanoma. In the trial, 769 patients had standard surgical resection of the primary tumor and a sentinel node biopsy. If the biopsy showed evidence of disease, the patient had a complete nodal dissection. In the control arm, 500 patients underwent standard tumor resection and regional nodal observation. If a patient subsequently developed a palpable or radiologically detectable nodal metastasis, he or she had a complete lymphadenectomy.
At five years, 78.3% of the patients in the sentinel node biopsy arm were disease-free compared with 73.1% in the observation arm. Of the patients who had been found to have positive nodes-16% in the biopsy arm and 15.6% in the observation arm-there was an overall survival advantage for patients treated in the sentinel node arm, with a five-year survival rate of 90.2% vs 72.3% in the observation arm. There was, however, no difference in melanoma-specific survival or overall survival between the two trial arms when all patients, both those with and without nodal disease, were included in the analyses. The current analysis is the third of five scheduled interim analyses, and investigators hope that an overall survival difference might appear in subsequent analyses.