EMI-137

Almost 50 % of papillary thyroid cancer (PTC) patients have central lymph node metastases (CLNM), which are associated with a high risk of persistent or recurrent disease. However, the practice of performing a prophylactic central lymph node dissection (PCLND) routinely remains controversial. The proponents argue that without a PCLND, PTC patients with positive lymph nodes have an increased risk of local recurrence, and postponed node dissection leads to with 5-6 fold higher risk of morbidity. If performed, PCLND in clinical node negative patients increases staging to pN1 in more than 50% of the cases without increasing survival. The complication rate in PCLND is lower when compared to a technically challenging re-exploration in recurrent disease, with reported incidences of 0.6% and 7.3-20%, respectively. Opponents of routine PCLND point out the lack of randomized clinical trials and object to treatment-induced hypo-parathyroidism and recurrent nerve damage for the N0 patients. Currently, no diagnostic tool is available which reliably identifies these patient categories. Therefore, there is a clear need for novel diagnostic imaging modalities that overcome this issue. Molecular Fluorescence Guided Surgery (MFGS) is potentially such a diagnostic tool. The administration of NIR fluorescent tracers can increase detection accuracy of cancer and nodal metastatic tissue using macroscopic MFGS. Therefore, we aimed to identify a GMP-produced near infrared (NIR) tracer that potentially has a high target-to-background ratio in PTC compared to normal thyroid tissue. Tyrosine-protein kinase Met (c-Met) is significantly upregulated at the protein level in PTC compared to normal thyroid tissue. The investigators therefore hypothesize that the GMP-produced NIR-fluorescent tracer EMI-137 (targeting c-Met, peak emission at 675 nm range) might be useful for intraoperative imaging of PTC and nodal metastases. The investigators' aim is to investigate if the administration of EMI-137 is a feasible approach to detect PTC nodal metastases. Ultimately, this method might be useful to improve patient selection for CLND. Eventually, we might also be able to visualize multifocality, more selective lateral neck dissections and asses residual tissue after thyroidectomy. Ultimately, all of these strategies may reduce overtreatment, morbidity, and costs while maintaining the same or better effectiveness with a lower recurrence rate and improved quality of life.