Koos Boeve

56 Chapter 3 also included in a Dutch multicenter SNLB validation trial before the SLNB was incorporated in the Dutch guidelines. Written informed consent was obtained from each of these five individual patients after study approval from the ethical board of the UMCG [7]. Patients and setting Patients treated at the Oral & Maxillofacial Surgery or Otorhinolaryngology / Head & Neck Surgery departments of the University Medical Center Groningen (UMCG) (n = 91) or the Oral & Maxillofacial Surgery department of the Medical Center Leeuwarden (MCL) (n = 12) between October 2008 and September 2016 were included. Inclusion criteria: clinically T1- 2N0 OSCC; primary treatment by surgical resection; neck staging by SLNB. Twelve patients were excluded because of pT3-4 tumours (n = 2), multiple primary head and neck squamous cell carcinoma at diagnosis (n = 5), incomplete SLNB protocol (n = 3) and, multifocal tumours without free surgical resection margins and uncertainty of clear injection around the tumour (n = 2). Clinico-pathological data of the 91 (100%) patients were retrospectively collected from the digital patients files (Table 1). Clinical neck staging was performed by extensive palpation and CT or MRI (UMCG) or by 18 F-FDG positron emission tomography (PET)-CT (MCL) scanning and in both centers followed by US-guided with fine needle aspiration cytology in case of enlarged (>1 cm) of otherwise suspicious nodes. Cases with a positive SNLB underwent a modified radical neck dissection (MRND) during a second surgery. Routine follow-up of the neck was used as reference standard in the SLNB negative patients. In total seven (8%) patients received adjuvant radiotherapy for irradical tumour resection of the deep margin (n = 4), pN2 neck stage (n = 3) and/or extranodal extension (n = 1). Sentinel lymph node biopsy procedure One day before surgery 99m Tc-nannocolloid (median 100 MBq, IQR 95-102, data available for 90 patients) (GE Healthcare, The Netherlands) was injected around the tumour. Dynamic visualization by lymphoscintigraphy followed immediately after injection for 20 minutes in anterior or oblique views (20x60s s, 128x128 matrix) and also immediately static images (300 s, 256x256mmatrix) in anterior and lateral direction were generated (Ecam or Symbia S (MCL), or SymbiaT (UMCG), Siemens, Knoxville,TN, USA).The static visualizationwas repeated after 2-4 h. Thereafter visualization by SPECT-CT scanning of the head and neck using a two-headed gamma camera equipped with parallel-hole ultra-high resolution collimators and a 2-slice CT scanner (32 views of 20 s, 128x128 matrix; mAs 30, kV 110, 3.0 mm slice) was performed, only in the UMCG. SPECT-CT scanning was added to the protocol after treatment of the first five patients. The position of the SLN was marked on the overlaying skin with a Cobalt-57 point-source-marker and a gamma-probe (Europrobe, EuroMedical Instruments, France (MCL) and Neoprobe, Mammotome, Cincinatti, Ohio (UMCG)). The first lymph nodes in a lymphatic path from the tumour were marked as SLNs.