Page 23 - Sentinel lymph node biopsy in oral cavity cancer - Inne J. den Toom

OUTLINE OF THIS THESIS 1 The first part (chapters 2 and 3) will present the current status of the SLNB procedure in the Netherlands. The second part (chapter 4, 5, 6) is about defining potential applications of the SLNB procedure. Finally, in chapter 7 and 8, improvements of the current technique will be explicated. In chapter 2 we described the accuracy of the SLNB procedure in a singlecenter study in the Netherlands, presenting the identification rate, sensitivity and negative predictive value. Also, we perform survival analysis in general and according to the size of metastasis in the SLN. In chapter 3 the largest cohort of SLNB procedures in oral cavity cancer worldwide is presented due to a multicenter study design of 5 Dutch head and neck centers. Interestingly, the accuracy of the SLNB procedure will be compared to a cohort of patients who had undergo END before the SLNB was introduced. By absence of a randomized controlled trial in literature, this study provides the highest evidence of the effectiveness of both procedures in early stage oral cancer. Chapter 4 describes one of the advantages of the SLNB procedure, by classifying the metastases based on their size. Due to the extensive histopathological examination very small tumour deposits (isolated tumour cells, micrometastasis) are detectable. The influence of such metastases on additional neck dissections and survival is presented in a cohort of 199 patients, and available literature is evaluated. Depth of invasion has been determined as important prognostic factor and has recently been incorporated in T-stadium of the 8th TNM classification. Most often, depth of invasion has been correlated to lymph node metastasis of END specimens. In chapter 5, we evaluated the risk of having nodal metastasis correlated to depth of invasion, using the SLNB procedure as gold standard of nodal disease. The SLNB procedure has increasingly been implemented during the last years in oral cancer, however, regularly only patients with an untreated neck are eligible. Chapter 6 describes the applicability of the SLNB procedure in patients who are previously treated in the neck. 21