Page 62 - Sentinel lymph node biopsy in oral cavity cancer - Inne J. den Toom

Chapter 3 small number of cases with ITC and MiM additional non-SLN metastases were found in complementary neck dissection specimens.39 Our study demonstrated in only 2 cases with ITC or MiM additional non SLN metastases (5%). Due to the limited number of studies in literature, it is difficult to determine the value of complementary neck dissections in case of ITCs or MiM. In addition, one has to consider that complementary neck dissection specimens are not examined as meticulously as SLNs. Currently, data is lacking to safely omit therapeutic neck dissections in case of ITC or MiM. Disease specific survival of the false-negative cases of both cohorts addresses an important finding. SLNB FN patients had an almost equal DSS compared to the true positive patients. In contrast, in the END FN cohort a dramatic decreased survival was shown compared to the END TP patients. Our data clearly underlines the importance of correct staging using a minimal invasive method, given this inferior survival for FN patients, specifically in the END cohort. One of the limitations of this study remains its retrospective design. In the END cohort a considerable number of the patients were diagnosed as clinically N0, based on potentially dated ultrasound, CT and MRI scanners and before widespread application of FDG-PET for staging purposes. There is also a significant difference in pT stage with more pT2 staged tumours in the END cohort. A possible explanation is that the majority of patients in the END cohort was selected based on depth of invasion (> 4 mm), inevitably resulting in less pT1 tumours. For that reason, we compared also the sensitivity and NPV between SLNB and END divided by pT stage and found no significant difference. Besides the diameter of the tumour reflected in pT stage in the 7th TNM classification, nowadays the 8th edition is used.40,42 In the 8th edition, depth of invasion is newly incorporated for T stage and therefore our results could not directly be translated to the 8th TNM classification.43,45 Another important difference between both groups is the prolonged follow-up in the END cohort. Although we expected (and identified) regional recurrences particularly in the first 2 years, a longer follow-up could result in more regional recurrences and/or disease specific deaths. CONCLUSIONS In conclusion, detection of lymph node metastases in oral cancer using sentinel lymph node biopsy is as accurate as elective neck dissection, except for floor of mouth tumours. SLNB showed higher disease specific survival rates as compared 60