Response to immunohistochemical markers' conversion after neoadjuvant chemotherapy in breast cancer patients: association between imaging and histopathologic analysis

Background Breast ultrasound and mammography were used in the detection of residual tumor after neoadjuvant chemotherapy. The aim of this study was to evaluate the correlation between clinical and pathological responses with breast density and IHC marker conversion to understand how this information might be used in the future to direct treatment. Methods We included 119 patients who underwent CNB and followed NACT. The breast density assessment was based on the mammography examination performed at the time of diagnosis. We evaluated the clinical and pathological responses to NACT by the UICC and Miller-Payne grading systems, respectively. Results Of 119 patients who met the inclusion criteria, patients with high pre-treatment IHC markers levels showed higher expression of IHC markers regardless of the post-treatment IHC marker level at baseline. However, breast and node tumor sizes before and after NACT were negatively correlated with hormone receptor conversion and positively correlated with Ki-67 conversion (P < 0.05). Patients with low BD were more likely to have a cCR, pCR, TNBC, and postmenopausal status than those with a high BD (P < 0.05). BD was significantly associated with PR and Ki67 conversion but not ER conversion. Conclusion Our prospective observational study demonstrated that IHC marker conversion could be used to identify lesion size changes and BD. We also found that a high BD was linked to clinical and pathological responses, molecular subtype, and menopausal status. In the future, additional studies are required to validate the predictive value identified by this research.