In view of this finding, it is hypothesized that rT3 accumulates in metastatic colorectal cancer via deiodinase type 3 (D3) activity, D3 converts T3 to T2, thus attenuating T3 action locally, and the T4/T3 ratio is increased, supporting a critical role of thyroid hormone in modulating colorectal cancer metastasis. Here, TG is linked to colorectal cancer.