Koos Boeve

204 Chapter 10 The sentinel lymph node biopsy (SLNB) was introduced in head and neck cancer staging as a minimally invasive alternative for an elective neck dissection in detecting occult neck metastases. Meta-analyses of SLNB accuracy showed heterogeneity in the existing studies for reference standards, imaging techniques and pathological examination. In chapter 3 we determined the accuracy of the SLNB in detecting occult metastasis in 91 consecutive patients with primary cT1-2N0 OSCC treated by primary resection and neck staging by SLNB procedure between 2008 and 2016. The SLNB consisted of lymphoscintigraphy, SPECT-CT- scanning and gamma probe detection. Routine follow-up was the reference standard for the SLNB negative neck. Histopathological examination of sentinel lymph nodes (SLN) consisted of step serial sectioning, haematoxylin-eosin and cytokeratin AE1/3 staining. In all cases SLNs were harvested. A total of 27% patients had tumour-positive SLNs. Four patients were diagnosed with an isolated regional recurrence in the SLNB negative neck side resulting in an 85% sensitivity and a 94% negative predictive value. We concluded that the SLNB is a reliable procedure for surgical staging of the neck in case of oral cT1-2N0 SCC. It is well known that patients with OSCC suffer a high risk for local recurrences (20-30%) and an annual risk of 3-4% for developing second primary tumours. The treatment of recurrences and second primary tumours is hampered by the previous treatment of the neck due to altered lymphatic drainage patterns. SLNB could be helpful to assess these altered lymphatic drainage patterns. Current evidence about the drainage patterns in previously treated OSCC patients using SLNB is limited to two small studies (n = 22 and n = 5). In chapter 4 we retrospectively analysed 53 cT1-2N0 OSCC patients from three centres, who underwent SLNB between 2007 and 2016, after a history of neck surgery or radiotherapy. The SLNB procedure was identical to the procedure used in chapter 3. SLNs were detected in 85% of the cases. The SLNB had a sensitivity of 75% and negative predictive value of 98%. Unexpected drainage patterns were observed in 30% of the cases and in 12% no visible lymphatic drainage patterns were observed. We concluded that the SLNB seems to be a reliable procedure for neck staging of cT1-2N0 OSCC patients with a previously treated neck and enables visualization of unexpected drainage pattern variability. Oral maxillary cancer is relatively rare compared with other anatomic subsites of oral cavity cancer (eg. tongue and floor of mouth) and is rarely included in studies on oral lymphatic drainage patterns. For this location of OSCC, low metastasis rates and drainage patterns to parapharyngeal located lymph nodes have previously been reported. In chapter 5 we retrospectively studied drainage patterns of 11 patients with oral maxillary cancer that underwent a SLNB procedure. In 10 patients, SLNs were detected and harvested at cervical levels. In two patients, a parapharyngeal SLN was also detected. We concluded that in the majority of the maxillary cancer patients SLNs are located in cervical levels and only in a minority in the parapharyngeal area.