Comparison and Significance of Immunohistochemical Expression before and after Treatment in Cases with Partial Response to Neoadjuvant Chemotherapy for Breast Cancer

DONG Chunlong

doi:10.14033/j.cnki.cfmr.2026.04.004

Abstract：Objective:To compare the expression of immunohistochemistry(IHC)before and after neoadjuvant chemotherapy(NAC)in cases of partial response to breast cancer,and to explore its clinical significance.Method:A retrospective study was conducted on 96 breast cancer patients who achieved partial response after neoadjuvant chemotherapy(NAC)and were admitted to the hospital from January 2021 to December 2023.The immunohistochemical(IHC)markers(ER,PR,HER2,Ki-67)of pre-NAC puncture biopsy specimens and post-NAC surgical residual lesions were paired and analyzed to evaluate the transformation of expression levels and molecular subtypes.Result:The positive rates of ER,PR and Ki-67 showed statistically significant differences(P<0.05).The positive rates and expression percentages of PR and Ki-67 decreased more significantly,and the HER2 status was highly stable.The stability of the molecular typing Luminal B(HER2-)type and Luminal B(HER2+)type is relatively low,and they tend to transfer to the Luminal A type.Luminal A type,HER2 overexpression type,and triple-negative breast cancer(TNBC)type all have high stability.Conclusion:In breast cancer patients with partial response to neoadjuvant chemotherapy(NAC),the biological characteristics of residual tumors undergo significant alterations,manifested as downregulation of estrogen receptor(ER)and progesterone receptor(PR)expression,decreased Ki-67 index,and a certain proportion of molecular subtype conversion.Postoperative re-evaluation of residual lesions through immunohistochemical(IHC)testing and molecular subtype assessment holds critical guiding value for formulating subsequent precision adjuvant therapy regimens.