Serum TFF2 levels in breast cancer patients were significantly lower than in healthy individuals (TFF1: 1.48 ± 1.43 ng/ml, P = 0.0004, TFF2: 3.90 ± 1.90 ng/ml, P = 0.0003, TFF3: 6.96 ± 1.45 ng/ml, P = 0.0313) (Fig. 1a–c). Here, TFF2 is linked to breast cancer.