Ultrasound and immunohistochemical predictors of neoadjuvant chemotherapy response in breast cancer.

Background: Neoadjuvant chemotherapy (NAC) has become a crucial treatment strategy for breast cancer. However, responses to NAC vary significantly among patients-while some achieve a pathological complete response (pCR), others exhibit limited efficacy. Therefore, identifying reliable preoperative predictors of NAC response is essential for optimizing personalized treatment decisions. This study aims to: (I) evaluate the predictive value of preoperative ultrasound characteristics in combination with immunohistochemical markers for NAC efficacy in breast cancer patients; (II) identify key indicators that synergistically enhance predictive accuracy; and (III) provide a comprehensive and practical foundation for clinical decision-making. Methods: We retrospectively analyzed breast cancer patients who underwent NAC at The Second Hospital of Lanzhou University from October 2020 to December 2023. Postoperative pathology was graded using the Miller-Payne system, with grades 4-5 classified as the effective group and grades 1-3 as the ineffective group. Preoperative ultrasound features and immunohistochemical markers from core needle biopsy-estrogen receptor (ER), progesterone receptor (PR), and Ki-67 proliferation index-were compared between the two groups. Variables showing statistical significance in univariate analysis were entered into a multivariate logistic regression model to develop a predictive nomogram. Model performance was assessed using receiver operating characteristic (ROC) curves, calibration plots, and the area under the ROC curve (AUC). The optimal cutoff point was determined by the maximum Youden index, and the corresponding sensitivity and specificity were recorded. Results: A total of 101 patients were included: 56 (55.45%) in the effective group and 45 (44.55%) in the ineffective group. PR expression was significantly associated with Breast Imaging Reporting and Data System (BI-RADS) classification (P=0.03). Univariate analysis showed significant differences between groups in Ki-67, ER, PR, and ultrasound-measured lesion reduction after chemotherapy (P<0.05). Multivariate analysis identified negative PR status [odds ratio (OR): 0.18, P=0.01], unifocal lesions (OR: 0.26, P=0.04), and lesion reduction after chemotherapy (OR: 8.16, P=0.02) as independent predictors of favorable NAC response. The model achieved an AUC of 0.80 [95% confidence interval (CI): 0.72-0.80]. At the optimal cutoff, the maximum Youden index was 0.46, with a sensitivity of 0.70 and a specificity of 0.76. Conclusions: Preoperative ultrasound characteristics and immunohistochemical markers in breast cancer patients exhibit significant predictive value for NAC efficacy, providing valuable insights to guide clinical treatment decisions.