MUC5AC and thyroid cancer: Currently, there are few tumor markers that have been shown to be sialylated glycoproteins and have demonstrated an impact at the clinical level, such as a-fetoprotein from liver cancer, CA-125 from ovary cancer, thyroglobulin from thyroid cancer, PSA from prostate cancer, and mucin from bladder cancer [77], hence the importance of identifying and characterizing this type of antigen due to its potential clinical application.