Even with the strong preliminary data from the ACOSOG trial, researchers caution that a trial testing the efficacy of sentinel node biopsy alone, without complete neck dissection, would be needed before the procedure should be used as the standard of care. Such a trial could be a randomized trial similar to the one Dr. Morton and colleagues recently completed, in which patients were randomly assigned to either sentinel node biopsy or observation of the nodal basin, with lymphadenectomy if positive nodes are detected.
Explore This IssueJuly 2007
Not everyone is waiting for such clinical trial data, however. For example, Barry M. Rasgon, MD, Attending Physician and Director of the Research Otolaryngology Head and Neck Residency Program at Kaiser Hospital in Oakland, CA, has been using the procedure for about 10 years, in both melanoma and squamous cell cancers of the head and neck. The thing about sentinel node biopsy is that it is, bar none, the most accurate, cost-effective, least invasive way to stage a clinically negative neck.
He admitted that there are numerous potential pitfalls with the procedure but thinks they can be overcome without too much difficulty. When he first started trying the technique, he followed the general surgery literature in terms of the amount of radioactive tracer and volume to inject. It was a big black hole. Everything was hot, he said. With a substantial reduction in both radioactivity and volume, to about 30 microCuries in 0.1 or 0.2 mL, the nodes become apparent, and the shine from the primary injection site does not overwhelm everything else. To further minimize the problem when he is dealing with a squamous cell cancer on the tongue, Dr. Rasgon bends a small piece of lead around the primary injection site. Even with such hints, though, it can be a tough technique to master because of the complex lymphatic drainage in the neck. You probably need to do about 30 of these with someone who knows what they are doing to get good at it, Dr. Rasgon said.
Remarkably, the technique has enabled him to identify two recent cases in which micrometastases in the sentinel nodes had spread beyond the node itself. We think there needs to be a certain volume of tumor in the node to do that. But clearly it can do that from a small focus of micrometastases in the paracortical area and go right through the capsule to the surrounding tissues, Dr. Rasgon said.