Abstract: Objective The aim of this study was to explore the expression of B7 homologou 4(B7-H4)in breast cancer tissues, and its correlation with axillary lymph node metastasis in patients after neoadjuvant chemotherapy. Methods A total of 82 patients with breast cancer who received neoadjuvant chemotherapy in our hospital from January 2020 to June 2022 were selected as the subjects. Biopsies were used to evaluate the pathological types of tumors. After neoadjuvant chemotherapy and modified radical mastectomy for breast cancer, breast cancer tissue and adjacent normal tissue samples were obtained, and immunohistochemistry was used to analyze the expression of B7-H4 in tissues. According to the pathological diagnosis of postoperative patients, they were divided into the axillary lymph node metastasis group and the axillary lymph node non-metastasis group. Univariate and multivariate logistic regression were used to analyze the factors affecting lymph node metastasis after neoadjuvant chemotherapy. The receiver operating characteristic(ROC)curve was used to analyze the diagnostic value of B7-H4 for axillary lymph node metastasis in breast cancer patients after neoadjuvant chemotherapy. A nomogram model was constructed, and the ROC curve and calibration curve were used to verify the discrimination and accuracy of nomogram model. Results The positive rate of B7-H4 expression in breast cancer tissue was higher than that of adjacent tissue(85.37% vs. 9.76%, P＜0.05). Multivariate logistic regression analyses showed that B7-H4 expression, the number of positive axillary lymph nodes before surgery, the efficacy of neoadjuvant chemotherapy, the tumor T stage after neoadjuvant chemotherapy, ER status, HER2 status, Ki-67 expression, and the number of cycles for chemotherapy completion were risk factors for axillary lymph node metastasis in breast cancer patients after neoadjuvant chemotherapy(P＜0.05). The area under the ROC curve for B7-H4 in diagnosing axillary lymph node metastasis was 0.783(95% CI:0.738-0.836, P＜0.001). C-index was 0.819(95% CI:0.722-0.903, P＜0.001), the reference curve and the fitting curve had a good agreement, and the nomogram showed good discrimination and accuracy. Conclusion B7-H4 is highly expressed in breast cancer tissues, and its high expression is positively correlated with axillary lymph node metastasis in patients after neoadjuvant chemotherapy.

Key words: B7 homologue 4, Breast cancer, Neoadjuvant chemotherapy, Axillary lymph node metastasis, Risk factor