Mutevelizade, GKocer, NEReyhan, M2024-07-182024-07-180914-71871864-6433http://akademikarsiv.cbu.edu.tr:4000/handle/123456789/8763Objective This study aimed to investigate immunohistochemical staining of sodium iodide symporter (NIS) and its effect on response to I-131 therapy in differentiated thyroid carcinoma patients. Methods We evaluated NIS expression, the intracellular distribution of NIS, iodine-131 uptake in residual tissues on post-ablation I-131 whole body scan, and the ablation status after 100 mCi I-131 therapy. We also investigated NIS expression and localization in tumoral paraffin-embedded tissues. Results In this retrospective study, 35 patients (mean age 44.17 +/- 12.9 years, 27 female, 8 male) were studied. Twenty-one of these patients responded to radioiodine therapy, and 14 did not. NIS expression and iodine-131 uptake in residual tissues post-ablation I-131 whole body scan were not statistically significant. When we compared the patients who responded to radioiodine therapy and the poor responder group, NIS expression and iodine-131 uptake in residual tissues did not demonstrate statistically significant difference [(p = 0.308) (p = 0.985) respectively]. 47.6% of the patients in the successful ablation group and 85.7% in the unsuccessful ablation group had intracellular NIS immunostaining. The difference was not statistically significant (p = 0.139). 52.4% of the patients in the successful ablation group and 7% in the unsuccessful ablation group had NIS immunostaining at the basolateral membrane. The difference was statistically significant (p < 0.05). Conclusions In conclusion, we did not find any significant difference between successful and unsuccessful ablation groups in terms of NIS expression; however, we concluded that the intracellular (cytoplasmic) localization of NIS is one of the leading causes of ablation failure regardless of NIS expression in DTC patients.EnglishSODIUM/IODIDE SYMPORTEREXPRESSIONNISASSOCIATIONCARCINOMAPAPILLARYSTRATEGYTISSUESGENEArticle