As a malignant tumor with high incidence in women, breast cancer has more than 50,000 new cases every year. Most patients have no obvious clinical symptoms in the early stage of the disease, resulting in great difficulty in clinical diagnosis and treatment [13]. Neoadjuvant chemotherapy is a systemic intervention before local treatment, which has a good effect. This method can reduce the tumor stage, reduce the tumor volume, and lay the foundation for the subsequent treatment of patients [14-15]. Clinically, breast cancer is divided into four types: Luminal A, Luminal B, HER-2 and triple-negative. The triple-negative type is not included in this study because it is not sensitive to chemotherapy drugs. The shape of different types of lesions is mostly irregular, the internal is mostly hypoechoic, and the echo is uneven, the echo is strong, the boundary is not clear, and the blood flow signal is mainly grade 2 and grade 3 [16]. In this study, there was no significant difference between Luminal A group, Luminal B group and HER-2 group in contrast-enhanced ultrasound and ultrasound elastography parameters (P>0.05). According to the results, different types of breast cancer have high response to neoadjuvant chemotherapy, and there was no significant difference between the results of contrast-enhanced ultrasound and ultrasound elastography. Previous studies have shown that neoadjuvant chemotherapy can create favorable conditions for surgery or further treatment. However, for breast cancer patients with indications, different factors lead to poor treatment effect, which not only delays the timing of surgery, but also affects the long-term survival of patients [17].
In this study, there were 13 cases of non-response to neoadjuvant chemotherapy in 74 breast cancer patients, accounting for 17.57%. PT, K1 and SR in the non-response group were higher than those in the response group (P<0.05). The reason for this may be that the echo of the lesion during ultrasound diagnosis is affected by the location of the tumor, the surrounding stress and tissue specificity [18], and the echo obtained is derived from the tissue components. Before neoadjuvant chemotherapy in breast cancer patients, the lesion tissue contains a large number of inflammatory cells and tumor cells, which leads to a higher sound transmission performance than normal tissue. Moreover, the new capillaries in the tumor cells increase, and the blood flow signals of contrast-enhanced ultrasound increase. However, after neoadjuvant chemotherapy, the internal environment of the lesion site changes, elasticity and density change, tumor cells are inhibited by chemotherapy drugs, new capillaries are reduced, and contrast-enhanced ultrasound shows reduced blood flow signals, so it can accurately predict the treatment response of patients [19]. Shear wave elastography uses an instantaneous pulse to generate shear waves in vivo, and calculates the elasticity of tissues by measuring the propagation speed of shear waves. This technology is the only real-time and quantitative method to measure the Young's modulus E of local tissues. After the patient received neoadjuvant chemotherapy, the cancer cells were killed and the tissue stiffness at the lesion site was reduced. Ultrasound elastography quantifies the hardness of the lesion, and SR obtained by ultrasound elastography is an index reflecting the hardness of the lesion. The greater the hardness of the lesion, the worse the effect of neoadjuvant chemotherapy of the patient [20], which can effectively judge the pathology and prognosis of breast cancer patients. Therefore, the stiffness of different tissues can be understood by SWV measurement before and after neoadjuvant chemotherapy in breast cancer patients, and the treatment plan can be adjusted according to the measurement results, so that the patient's prognosis can be good.
In this study, the indexes of contrast-enhanced ultrasound and ultrasound elastography change before and after breast cancer chemotherapy, and the images and measured values of contrast-enhanced ultrasound and ultrasound elastography can predict the effect of breast cancer chemotherapy. The combination of contrast-enhanced ultrasound and ultrasound elastography in predicting the response to neoadjuvant chemotherapy in patients with different molecular types of breast cancer was higher than that of single examination (P<0.05). The results showed that contrast-enhanced ultrasound combined with ultrasound elastography could predict the response to neoadjuvant chemotherapy in different molecular types of breast cancer. After chemotherapy, the blood flow signal in the breast cancer mass decreased and the grade decreased. The SR value of elastography decreased. This indicates that chemotherapy drugs kill tumor cells, leading to a decrease in CEUS and ultrasound elastography indicators. The combined application of the two methods, through ultrasound elastography for the differential diagnosis of the nature of the lesion, if it is a malignant tumor, there will be tissue fiber change, hardness increase phenomenon, and through the hardness change to realize the identification of the tumor boundary, so that the tumor after adjuvant chemotherapy may have decreased tumor hardness, microvascular reduction, tumor volume reduction or no significant change. However, the decrease of microvessels will change the elasticity of the tumor, and it will be affected by cell necrosis and apoptosis, which will affect the diagnostic results. Combined use of contrast-enhanced ultrasound can observe the blood flow and complete the qualitative diagnosis of the lesion, which can make up for the lack of single application of ultrasound elastography or contrast-enhanced ultrasound in the evaluation of the nature of the lesion, and can better guide the formulation of chemotherapy regimens for patients. Therefore, breast cancer patients should undergo ultrasound examination regularly during neoadjuvant chemotherapy, especially contrast-enhanced ultrasound and ultrasound elastography, to predict the development of the patient's disease. For patients who are not sensitive to chemotherapy, the plan should be adjusted as soon as possible to improve the prognosis of patients.
In conclusion, when different molecular types of breast cancer patients were treated with neoadjuvant chemotherapy, the indexes of CEUS and elastography before and after chemotherapy changed. The combination of CEUS and elastography has a high predictive value for the development of different molecular types of breast cancer, and can obtain high sensitivity and specificity, which can provide a reliable basis for the formulation and adjustment of adjuvant treatment plans.