Background  The shear wave elastic modulus of malignant breast lesions is often higher than that of benign breast lesions, and the occurrence of malignant breast lesions is often accompanied by high expression of Smad2/3 protein, which is related to the invasion and migration of cancer cells.

  Objective  To study the correlation between the expression of Smad2/3 protein and the elastic characteristics of breast lesions.

  Methods  From April to October in 2018, shear wave elasticity images (n=135) of 130 female patients with breast diseases from the ultrasound department of the First Medical Center of Chinese PLA General Hospital were collected. The maximum elastic modulus, average elastic modulus, minimum elastic modulus, the elastic ratio of lesions to peripheral parenchyma and ”stiff rim sign” were recorded. After surgery or biopsy, the breast pathological tissues of patients were collected. The expression level of Smad2/3 was detected by immunohistochemical method to compare the difference in the expression of Smad2/3 between benign and malignant breast lesions.

  Results  Among the 135 lesions, 51 were malignant and 84 were benign. The expression level of Smad2/3 of the malignant lesions was significantly higher than that of the benign lesions (0.299 ± 0.011 vs 0.104 ± 0.009, P＜0.001). Smad2/3 expression level was positively correlated with the maximum elasticity, average elasticity, and the elastic ratio of lesions to peripheral parenchyma (r=0.657, 0.640, 0.470, P＜0.001, respectively). The expression of Smad2/3 in lesions with “stiff rim sign” was statistically higher than that in lesions without “stiff rim sign” (P＜0.001). Moreover, the combination of the expression of Smad2/3 and “stiff rim sign” could improve the diagnostic sensitivity (100%) and accuracy (94.56%) greatly for the differential diagnosis of benign and malignant breast lesions.

  Conclusion  The expression level of Smad2/3 is correlated with the maximum elastic modulus, the average elastic modulus, the elastic ratio of lesions to peripheral parenchyma, and the “stiff rim sign”. The combination of the expression of Smad2/3 and "stiff rim sign" may be helpful for the diagnosis of breast cancer.