Koos Boeve

96 Chapter 5 recommended to study the accuracy of the SLNB in oral maxillary cancer. However, in this study they were not excluded because the still highly valuable information for clinicians; still existing drainage patterns to sentinel lymph nodes at cervical level in previously treated patients. Patient #11 had no visible sentinel lymph nodes at the lymphoscintigraphy more than 20 years after previous treatment with neck dissection and radiotherapy. Absence of detectable sentinel lymph nodes could be explained by the previous treatment of the neck, however other studies shows also a few patients without detectable sentinel lymph nodes, even when they had no previous neck treatment [20,24]. For a long time, a low metastasis rate of oral maxillary cancer has been the general view, probably driven by earlier results of low regional failure in oral maxillary cancer combined with a possible parapharyngeal lymphatic drainage pattern, there was no indication for an END [10]. However, more recent studies reported the cervical metastasis rate for maxillary OSCC is at least as high as OSCC originating from other anatomic regions. Also, in case of watchful waiting, a lower survival ratewas reportedwhen patients developed latemetastasis [11,14,16-19]. The higher metastasis rate and the shorter survival of maxillary OSCC with regional metastasis have indicated the need for ENDs in maxillary OSCC, especially in pT3- 4 but also in pT1-2 tumors [11-17]. Although ENDs are effective in preventing regional recurrences at the cervical level, it still leads to 70% overtreatment and possible morbidity (e.g. reduced shoulder movement, pain or lymph edema) [7,25,26]. To reduce overtreatment of the neck and to lower the complication rate, SLNB has been introduced in OSCC [23]. Recently, Den Toom et al. have shown that SLNB in OSCC adequately selects patients with cT1-T2N0 OSCC for additional neck dissection or follow-up (sensitivity of 93% and a negative predictive value of 97%). In that study, the sentinel lymph node identification rate by preoperative lymphoscintigraphy was 98% [20]. However, patients with maxillary OSCC were not included in that study. In this single-center retrospective study only 11 patients, with different tumor pathology and tumor status, could be analyzed because of the relative rarity of this tumor location. Based on our results it seems that oral tumors located at the maxilla also preferentially and frequently drain to the cervical neck levels and not so much parapharyngeally. We hypothesize that when the SLNB procedure shows a sentinel lymph node either in the neck or parapharyngeally, a personalized strategy should be applied. If accessible, the sentinel lymph node could be surgically removed and if the sentinel lymph node is located parapharyngeally, radiotherapy could be considered, depending on the risk of metastasis. The results of this small heterogeneous cohort support the need for further studies to assess lymphatic drainage routes and the possible diagnostic value of the SLNB in maxillary OSCC.