Correlation of clinicopathological outcomes with changes in IHC4 status after NACT in locally advanced breast cancers: do pre-NACT ER/PR status act as better prognosticators?

Background: Following neoadjuvant chemotherapy (NACT) for breast cancer, changes in estrogen receptor (ER), progesterone receptor (PR), HER2 status, and Ki-67 index (IHC4 status) and its correlation with pathological complete response (pCR) or relapse-free survival (RFS) rates could lead to better understanding of tumor management. Patients and methods: Pre- and post-NACT IHC4 status and its changes were analyzed in 156 patients with breast cancer. Associations between pCR, RFS rates to IHC4 status pre- and post-NACT were investigated. Results: pCR was found in 25.3% patients. Both ER and PR positive tumors had the lowest (14.3%) pCR compared to ER and PR negative (29%) or either ER-/PR-positive (38.6%) tumors. PR positivity was significantly associated with less likelihood of pCR (15% versus 34%). The pCR rate was low for luminal A subtype (13.68%) compared to 24.36%, 26.31%, and 33.33% for luminal B, HER2-enriched, and triple-negative subtypes, respectively. There was significant reduction in ER expression and Ki-67 index post-NACT. RFS of patients in whom the hormonal status changed from positive to negative was better compared to those of patients in whom the hormonal status changed from negative to positive. Conclusion: Although changes in IHC4 occurred post-NACT, pre-NACT hazard ratio status prognosticated RFS better. pCR and RFS rates were lower in PR-positive tumors.