A percentage of patients with early stage squamous cell carcinoma in the oral cavity will have microscopic spread of cancer to the lymph nodes, he said. The majority of patients who do not truly need treatment to the neck are treated in order to catch the ones who truly need treatment.
Explore This IssueJanuary 2009
Whereas in breast cancer and melanoma one to three sentinel nodes is the norm, in head and neck cancer, due to lymphatic drainage patterns, Dr. Civantos said three or four sentinel nodes are likely to be detected. We dissect any node that is up to 10% as hot as the hottest node.
When do you know if you have a histologically negative sentinel node? If the sentinel node is abnormal we will get a frozen section, but otherwise, there will be step sectioning and immunohistochemistry, he said. You want that done quickly so you can re-explore if the patient has a positive node before inflammation sets in the head and neck. The histology can be turned around in three days so you can re-explore the patient if you find a positive node.
Candidates for Sentinel Node Biopsy
Dr. Civantos said that the sentinel node biopsy procedure should be attempted in a patient population in which most of the individuals would be expected to have negative nodes. If the procedure is attempted on later-stage patients, he said the procedure would not be warranted. If you need to reoperate on 50 percent of the patients, then this technique does not make any sense. It is a great technique if you select a population at low risk-perhaps patients who, in the past, would have been candidates for a watchful waiting approach, he suggested.
In our trial we did have patients with minimally invasive tumors who did have positive sentinel nodes and those are patients who might have been treated with a watchful waiting approach in many people’s hands, he said. Seventy to 80 percent of the patients we are treating with neck dissection don’t need it. [But] if your patients did need it and you refer to watchful waiting, there is a lower chance of cure.
Details of the Trial
Dr. Civantos said the Z0360 protocol involved 34 investigators from 25 institutions. It was a very simple protocol that duplicated the validation trials that were done for melanoma and breast, he said. Basically patients with resectable T1 or T2 early oral cancers underwent preoperative injection of radionucleotide and radiolymphoscintigraphy, followed by resection of the primary tumor. Through a smaller incision, we attempted to mimic sentinel node biopsy in the true setting using gamma probe guidance. The incision was then extended and a selective neck dissection was then performed.