We did not find any significant association between NIS expression in the membrane and age, tumor size, tumor capsule, multifocality, lymphocytic infiltration, vascular invasion, lymph node metastases, tumor margins, distant metastases, staging, BRAF, NRAS and TERTp status, additional treatments, disease-free status at one year, disease-free status at the end of follow-up or disease-specific survival in the DTC group. When we analyzed NIS expression between WT PTCs and those harboring any of the studied mutations, we verified that NIS-positive expression was significantly more frequent in WT PTCs (P = 0.01) (Table 2). The number of RAI therapies, as well as the cumulative dose of RAI, did not differ significantly between patients with or without NIS expression in the basolateral membrane of primary tumor’s cells. Table 2Associations between NIS expression and clinicopathological and molecular features in PTCs.NIS immunoexpressionP valueNegativePositiveGenetic background n = 118 WT45 (41.3%)8 (88.9%) Mutated#64 (58.7%)1 (11.1%)0.011#BRAF, NRAS or TERTp mutations.