Objective To judge the accuracy of ultrasound examination in evaluating the efficacy of neoadjuvant chemotherapy (NAC) and the size of residual lesion, and to analyze the factors influencing of accuracy of evaluation.

Methods A total of 260 patients with invasive breast cancer who underwent NAC were enrolled to calculate the differences between the preoperative maximum tumor diameter measured by ultrasound and the postoperative maximum pathological diameter of all patients, and their correlation and the clinicopathological features influencing the difference between them were analyzed.

Results Of 260 patients, 78 patients obtained pathological complete response (pCR). The sensitivity, specificity, positive predictive value and negative predictive value of pCR after ultrasound assessment of NAC were 82.1%, 88.4%, 75.3% and 86.3%, respectively. The maximum diameter of the tumor measured by ultrasound after NAC was (19.8±14.3) mm, and the maximum diameter of the residual tumor measured by postoperative pathology was (17.9±16.3) mm. The maximum tumor diameter measured by ultrasound was significantly correlated with the maximum residual tumor diameter measured by postoperative pathology (r=0.721, P < 0.001). Clinicopathological features such as mass margin, posterior echo, calcification, histological grade and ER expression state had significant influence on the consistency of residual lesion size by NAC ultrasound and pathological evaluation (P < 0.05). Ultrasound and histopathological assessment showed a good agreement in evaluating tumor with smooth margin, no change in posterior echo, no calcification in the mass, low histological grade, and negative for ER.

Conclusion In breast cancer patients with no calcification in the tumor, relatively smooth edge, no change in posterior echo, negative estrogen receptor, and low histological grade, ultrasound evaluation of NAC efficacy have higher accuracy, which can effectively help clinicians accurately determine the surgical scope of breast-preserving patients before surgery and formulate individual diagnosis and treatment plans.