Sentinel Node Biopsy - Update of Sentinel European Node Trial (SENT) and future direction for SNB in the Head and Neck
Oral cancer is a relatively common condition but debate persists regarding the optimum management of patients with transorally resectable early stage tumours and clinically N0 necks. As the threat of occult cervical metastasis rate is >20%, elective neck dissection (ND) has become the standard of care. Sentinel node biopsy (SNB) is another method of staging the neck1,2 and early data from the Sentinel European Node Trial (SENT) trial supports the safe application of SNB to oral squamous cell carcinoma. New techniques to improve the accuracy of the SNB such as 3D navigation and fluorescence will widen the scope of applications for SNB in the head and neck region,3.
Methods
A prospective observational EORTC approved study was commenced in 2005, with 14 centres that recruited 420 patients with radiologically (MRI/CT) staged T1-T2 N0 oral squamous cell carcinoma. SNB was undertaken by a standardised technique. An average of 3.2 nodes were removed per patient. Patients were excluded if the sentinel node (SN) could not be identified or adjuvant radiotherapy was applied in patients with a SN negative neck. A positive SN led to a ND within 3 weeks.
Results
Lymphoscintigraphy did not show a SN in one case (0.2%) and a SN was not identified at surgery in 5 cases (1%). Positive SNs were found in 23% (97/420) of patients and in the subsequent neck dissection 85% had no further positive nodes. A false negative result (FNR) occurred in 13% (15/112) of patients with occult disease, of whom 7 were subsequently rescued by salvage therapy. Recurrence after a positive SNB and neck dissection occurred in 20 patients of which 15 (75%) were in the neck and just 5 patients were rescued. Only minor complications (3%) have been reported with SNB. Disease specific survival was 94% with 1% of patients alive with disease at a median follow up of 52 months (range 15-78 months). The sensitivity of SNB was 87% and the negative predictive value 95%.
Conclusions
Preliminary data suggests that SNB is a reliable and safe technique for staging the clinically N0 neck in patients with early oral cancer.
References:
1. Ross GL, Soutar DS, Shoaib et al. The ability of lymphoscintigraphy to direct sentinel node biopsy in the clinically N0 neck for patients with head and neck squamous cell carcinoma. Brit J Radiol2002; 75: 950-958.
2.Broglie MA, Haile SR, Stoeckli S. Long Term Experience in Sentinel Node Biopsy for Early Oral and Oropharyngral Squamous Cell Carcinoma. Ann Surg Oncology 2011; 10(18); 2732-2738.
2. Renato A, Valdes O, Sergi VS, Nieweg OE. Technological innovation in the sentinel node procedure: towards 3-D intraoperavtive imaging. Euro J Nuc Med Mol Imaging. August 2010, 37 (8), 1449-1451.