ERBB2 and breast cancer: Moreover, they found that serum concentrations of TFF1 were lower in TNBC sufferers compared to non-TNBC sufferers, which correlated with the clinical features of BC sufferers, for instance, ER, PR, and HER2 status [56], whereas another study of BC reported that TFF1 was positively related to Circ-TFF1, and both of them were upregulated.