Koos Boeve

24 Chapter 1 SCOPE OF THIS THESIS The aim of this thesis was to analyse the prognostic or predictive value of clinical, histopathological and molecular tumour markers which are associated with (sentinel) lymph node status or with the detection of cancer in saliva of oral squamous cell carcinoma patients. Tumour infiltration depth has been a well-studied tumour marker for predicting lymph node status and survival in OSCC [22]. Also extranodal extension has been proven as predictive marker for OSCC. Recently, these histopathological markers were incorporated in the 8 th edition TNM classification [24]. In chapter 2 the potential impact of the changes within the 8 th edition pTNM classification on the prognosis and treatment strategy of oral squamous cell carcinoma compared the use of the“old”7 th edition pTNM classification in a series of 211 pT1-T2 patients with a long-term follow-up was evaluated. The sentinel lymph node biopsy procedure (SLNB) was introduced in early stage OSCC for detecting occult metastasis. A meta-analysis on SLNB procedure accuracy showed heterogeneity in the existing studies for reference standards, imaging techniques and pathological examination [30]. In chapter 3 the sensitivity and negative predictive value of the SLNB procedure in detecting occult metastases in cT1-2N0 OSCC was assessed. For this purpose, a well-defined cohort was used with clinical-follow up as reference standard for the SLN negative patients, SPECT-CT part of the imaging protocol and step-serial-sectioning and additional keratin staining as standard histopathological examination. Despite the relative common local recurrences and second primary tumours in OSCC, only one study with 22 patients reported on the SLNB procedure in patients with a previously treated neck [90]. The SLNB procedure also provides information about the individual lymphatic drainage patterns, that might be helpful in these previously treated patients with altered lymphatic drainage patterns. In chapter 4 the accuracy of SLNB procedure was assessed and lymphatic drainage patterns evaluated using a multicentre consecutive cohort of cT1-2N0 patients with a previously treated neck in three Dutch head and neck cancer centres. Maxillary tumours are relatively rare and evidence on drainage patterns of these specific locations is lacking. Conventionally, the opinion was that these tumours rarely metastasize or only to retropharyngeal located lymph nodes [91]. In chapter 5 we retrospectively determined lymphatic drainage patterns of 11 patients with maxillary tumours who had neck staging with the SLNB procedure.