Background: Salivary cancer is rare and comprises a variety of histological subtypes and clinical behaviors. There is no agreed method of estimating the risk of occult metastasis or managing the clinically N0 neck.Sentinel node biopsy (SNB) may offer a solution but previous studies have not produced a reliable imaging protocol. This study uses novel technology and trial methodology to develop a reliable SNB technique, with primary aim to identify peri-and intraglandular sentinel nodes.
Methods: IDEAL framework was used to undertake SNB in clinically node negative salivary gland cancer. Patients with cT1-2 N0 salivary cancer were eligible. Lymphoscintigraphy was undertaken using Tc-99 m labelled nanocoll. Injection technique as well as adjunctive use of freehand SPECT (fhSPECT), near-infrared (NIR) fluorescence imaging, and navigation-guided surgery were used and optimisied during the study protocol.
Results: 10 patients were recruited. Initial protocol of peritumoural injection of Tc99 m nanocoll showed poor image resolution. Subsequent adjustment to single intratumoural injection allowed identification of intraglandular sentinel nodes. Fh/SPECT and NIR fluorescence imaging found intraglandular lymph nodes otherwise not recognizable to the naked eye. In two cases occult lymph node metastasis were identified.
Conclusion: This study has shown the IDEAL framework is vital in allowing iterative changes in surgical protocol in the light of experience. This study has produced a reliable method for detection of sentinel nodes, in particular the ability to identify intra- and periglandular nodes with diagnosis of occult metastatic deposits and no false negative results. Our protocol can be readily transferred in to larger scale studies.
Keywords: Fluorescence guided surgery; Freehand; IDEAL framework; Neck dissection; SPECT; Salivary gland malignancy; Sentinel node biopsy.
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