Purpose: To evaluate the changes in biological markers ER, PR, HER2 and Ki67 in residual tumor after surgery for locally advanced breast cancer (LABC), and also to evaluate the outcome of breast cancer patients treated with neoadjuvant chemotherapy (NAC).
Methods: 144 breast cancer patients treated with NAC at the Oncology Institute of Vojvodina, Serbia from 2011 to 2015 were included in this study. Changes in biologic markers ER,PR, HER2/neu and Ki-67 were evaluated at diagnostic core biopsy and at the final surgery tissue specimens.
Results: Of 144 patients pathological complete response was achieved in 17 (12%) and these were excluded from the study. Evaluated were 127 patients with residual tumor after the final surgery. A change in hormone receptor status (ER,PR) occurred in 9.4% of the patients (ER in 5%, PR in 14.5%) and HER2 status in 4.7% of the patients. ER and PR status change from negative to positive was associated with better overall survival (OS), but without statistical significance (p=0.16). Patients with conversion of HER2 status from negative to positive lived longer (65 vs 42 months). Furthermore, it was determined that HER2 change from negative to positive was associated with better OS (p=0.03). Ki-67 changed in 17 (11.8%) patients. The decrease of Ki-67 expression after NAC was associated with better outcome. Median follow up was 37.5 months (range 16.2-76.8).
Conclusion: Changes in hormone receptor status, HER2 status and Ki-67 occurred after NAC in patients with LABC. A change from negative to positive hormone receptor status and HER2 status offers new treatment options, like endocrine therapy, and/or trastuzumab therapy for breast cancer patients. The decrease of Ki-67 expression after NAC was associated with better outcome.