High autophagy activity, as reflected by high numbers of LC3-II-positive puncta in the cytoplasm of thyroid tumor cells, was correlated in a proportional fashion with uptake of and clinical response to RAI and with higher remission rates, less tumor recurrences and less exposure to RAI therapy, at least in part by its association with functional SLC5A5 expression on the basal membrane of thyroid tumor cells. Here, SLC5A5 is linked to thyroid tumor.