11 General introduction In contrast to pharyngeal and laryngeal SCC for which concomitant postoperative platinum-based chemo- and radiotherapy (CRT) is the primary treatment approach, the management of OSCC predominantly encompasses surgery with or without adjuvant therapy (11). For this reason, OSCC wil be the main focus of this thesis. Clinical diagnosis Clinical examination – assessing risk factors and co-morbidities – as well as physical examination are part of the initial work-up of patients suspected to have OSCC. Palpation and preoperative imaging are critical to ascertain clinical tumor stage and guide decision making with respect to resection. By evaluating the extent/presence of the primary tumor, and/or regional disease, and/or metastatic disease, and/or synchronous secondary primaries, preoperative imaging helps in determining the feasibility of surgery and whether it can be performed with curative intent. Preoperative imaging involves either computed tomography (CT), magnetic resonance imaging (MRI), or [18F]-Fluorodeoxyglucose positron emission tomography (FDGPET) (3, 5, 12). Final diagnosis of OSCC is established through histopathological evaluation of biopsies (9). Tumor-node-metastasis classification Tumor stage is considered to be the major determinant of prognosis in North America and Western Europe (9). Histopathological diagnosis and tumor-node-metastasis (TNM) classification are necessary prerequisites for the clinical management of OSCC (13). Tumor-node-metastasis staging, evaluates the extent of tumor growth across a patient’s body using size of the primary tumor (T category), involvement of regional lymph nodes (N category), and presence of distant metastasis (M category). Besides recording the anatomical spread of cancer, the TNM staging system is used to stratify cancers into stage groups in view of clinical management (13). The most recent edition (eight) of the American Joint Committee on Cancer (AJCC) Cancer Staging Manual was implemented January 1st 2018. In contrast to the 7th edition it incorporates the depth of invasion (DOI) to determine T category and extranodal extension (ENE) to determine N category for OSCC (14, 15). 1
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