Koos Boeve

180 Chapter 9 life years (QALYs) after five years, respectively 3.63 versus 3.61 [32] and 3.70 versus 3.67 [31], equivalent with ~1 week profit in full health. Combining costs and effectiveness resulted in SLNB as most cost-effective strategy for neck staging in early stage OSCC regarding current known sensitivities and NPVs in both studies compared to the END or watchful waiting [31,32]. The fact that initial costs for a less invasive staging technique (SLNB) are comparably to an END procedure [32] could be explained by the additional use of hospital resources: imaging with lymphoscintigraphy and SPECT-CT, additional IHC and second surgery for the neck dissection in case of a positive SLN. The high accuracy, the cost-effectiveness and the minimally invasive character with low morbidity rates provided an expanding interest and implementation of the SLNB procedure in several national guidelines worldwide as reported in 2017 [33]. However, not all head and neck oncology centres in these countries use SLNB as standard care for the neck staging in earlystageOSCC[8,33].ForthoseunitsthatareinterestedintheSLNBprocedure,itisimportant to know that success depends on the experience of the surgeon [34]. Inexperienced surgeons can drop the NPV with 5% [35]. Moreover, a dramatically lower sensitivity can be expected with a surgical experience of less than 5 SLNB procedures, while an increase to a 94% sensitivity was reported with an experience of more than 10 SLNB procedures [34,36]. To reduce the risk of a low accuracy in the first period after implementation, Schilling et al. reported a step-wise training program for the implementation of the SLNB procedure [33]. Besides extensive training before the start of the implementation, also a combination of both the SLNB and END is recommended in the first 10 cases to evaluate the obtained accuracy of the SLNB and to prevent patients for regional recurrences as a result of the low experience [33]. In chapter 3 , we repeated the accuracy analysis after exclusion of the first patients with SLNB neck staging in our centre. The exclusion of these patients resulted not in a lower sensitivity or NPV in our study what might indicate that the SLNB procedure was implemented after thorough training of the surgeons [11]. Also important to notice is the multidisciplinary approach of the SLNB procedure [33]. Not only head and neck surgeons, also the physicians of the nuclear medicine and molecular imaging department must be trained. Moreover regarding the multidisciplinary character, currently, a single-day protocol (tracer dose of 40-50 MBq) or a two day protocol (tracer dose of 70-120 MBq) are recommended options for the SLNB procedure [15]. Single and two-day refer to the day of imaging and surgery. These single or two day protocols are only effective if imaging, surgery and pathology departments work together in a close cooperation and schedules and resources are aligned to each other as was stated in a 10-year evaluation of a study to the SLNB procedure in melanoma [37]. Summarizing, the SLNB procedure used in chapters 3, 4 and 5 met the recommendations of the current consensus guidelines for SLNB in early stage OSCC. Therefore, the reported