Koos Boeve

63 SLNB in early oral cancer Figure 2. Shine-through phenomenon example. Patient with a floor of mouth tumour on the left side close the midline (A), with a lymph node within the tumour hotspot (B) and an isolated regional recurrence after 19 months (C). DISCUSSION Synopsis of key findings In our retrospective cohort of 91 patients treated for cT1-2N0 OSCC, 4 patients developed isolated regional recurrence on the side of a negative SLNB. This resulted in 85% sensitivity and 94% negative predictive value. Comparison to previous studies The sensitivity and NPV are in agreement with the results of other studies with routine follow up as a reference: sensitivity range 80-94% and NPV range 88-97.5% (number of patients 59-415) [1,6-8,21]. A recent meta-analysis also showed comparable results: sensitivity 87%, NPV 94% [15]. The slightly higher NPV of this cohort compared to these meta-analyses can be explained by the relative short follow-up of some patients in our cohort. Two of the 66 patients (3%) with routine follow up after a negative SLNB were diagnosed with IRR. This percentage is much lower than the conventional 20% change of having IRR fromWeis et al, which is generally used in literature as threshold to choose between watchful waiting and END [22]. The low percentage IRR indicates the accurate selection of cT1-2N0 patients for neck dissection or routine follow up by performing a SLNB.