Sentinel Node Biopsy: High-Tech Method of Predicting Neck Status

The first article in this series discussed advances in endoscopic skull base surgery. Another new technology that is being developed for head and neck cancer surgery is the use of sentinel node biopsy for oral squamous cell carcinoma.

Sentinel node biopsy is a patient-driven phenomenon as well as a physician-driven phenomenon. People want you to do the same thing or get the same information while causing fewer side effects, explained Francisco J. Civantos, MD, Associate Professor of Head and Neck Surgery at the University of Miami in Florida.

We are hearing a lot about less-invasive ways to resect primary tumors-for example, laser surgery for hypopharyngeal and supraglottic tumors-and it would also be nice to also be able to apply less-invasive techniques to the neck, he said.

Dr. Civantos said that sentinel node biopsy is a diagnostic procedure, not a therapeutic one. The goal of the procedure is to identify who needs the larger operation and who doesn’t. It offers us the option where someday we may be doing a supraglottic resection of a cancer of the larynx and then doing a sentinel node biopsy and not having to radiate or worry about the neck nodes or do extensive dissections after we have taken out this little tumor endoscopically.

However, sentinel node biopsy for tumors of the oral cavity is different from sentinel node biopsy for melanoma or breast cancer, he said. The first question is proof of principle of whether injecting radionucleotide in the mouth will truly allow you to harvest the proper node and predict the status of the neck.

There are some differences when treating the oral cavity. Blue dye makes things messy and interferes with visualization. Nobody who does sentinel node biopsies for mucosal lesions uses blue dye, Dr. Civantos said in his lecture at the Combined Otolaryngology Spring Meeting last May. But the concept of having a second agent that will help with issues of background activity at the primary site is a good one. There is a new product called Sonozoid that may actually allow us to replace blue dye with an ultrasound-visible agent that can be injected into the primary site and allow us to deal with issues at the primary site. This is very preliminary and blue dye still works, but we haven’t used blue dye in our patients for sentinel node biopsy for oral cancer.

In sentinel node biopsy, he said, the primary tumor is injected with a tracer fluid. Nuclear imaging is employed to map the lymphatic drainage and indicate the location of the sentinel node. A gamma probe measures radioactivity in the neck and identifies the hot node, directing the surgeon to the location and subsequent removal of the sentinel node. If histology indicated the sentinel node is negative, then it precludes the necessity for cervical lymphadenectomy.