A New Technique

Karin MacCardle was very concerned when a small mole she noticed turned out to be malignant melanoma. Karin was referred to Dr. Daniel Roses at NYU who scheduled surgery immediately. Until recently, Karin's operation would have been a two part procedure: a wide and deep excision of the melanoma site, and removal of clusters of nearby lymph nodes (complete regional lymphadenectomy) as a precaution against the spread of cancer. That's because the thickness of the melanoma (2.8 mm) placed it in a category where 1 out of 4 patients has metastasis to the regional nodes. Traditionally, such patients would often have had all their regional lymph nodes removed.

Thanks to a new technique called sentinel node biopsy, Dr. Roses did not have to perform a complete lymphadenectomy for Karin. Instead of extensive surgery to completely dissect all the regional lymph nodes, Karin had only one node removed.

A Sentinel Node

It was not known until recently that the metastasis of melanoma occurs initially through a single lymph node. Dr. Roses and his colleague Dr. Matthew Harris helped pave the way for this observation while studying patients with head and neck melanomas. They found that lymph node involvement consistently included the nodes immediately adjacent to the melanoma site, rarely skipping over these nodes to more distant ones. This observation led to less extensive dissections of lymph nodes in the head and neck region.

Later research with radioisotopic imaging (lymphoscintigraphy) demonstrated that lymph draining from a melanoma site nearly always flowed first to a single node (the sentinel node) and that cancer cells rarely bypassed this node. If the sentinel node is free of melanoma, a surgeon can safely conclude that the lymph nodes further down the line are melanoma-free as well.