NTRK3 and thyroid cancer: NTRK1 gene fusions are also established in thyroid cancer, albeit less commonly than NTRK3 gene fusions [3, 10]; for example, Pekova et al. [10, 16] found that NTRK3 gene fusions were five times more common than NTRK1 gene fusions in their cohort of 846 patients with PTC.