Our results showed that there is no expression of Twist2 in normal breast tissues (0%, 0 of 7 cases), weak expression of Twist2 in benign breast diseases including mammaryadenosis, fibroadenosis, and mastitis (25%, 7 of 28 cases), and moderate to strong expression of Twist2 in malignant tumor (73.94%, 105 of 141 cases). Here, TWIST2 is linked to breast fibrocystic disease.