TPO and thyroid gland carcinoma: Two studies classified EVs based on their biochemical composition by isolating and analysing EVs expressing the thyroid tissue-specific marker, thyroid peroxidase (TPO) [37] in one, and the epithelial tumour markers known to be overexpressed in thyroid cancer, namely B7H3/CD276, MUC1, and EpCAM [69] in another.