Evaluation of ER and Ki-67 proliferation index as prognostic factors for survival following neoadjuvant chemotherapy with doxorubicin/docetaxel for locally advanced breast cancer

Background: The aim of the study was to identify reliable predictive biological markers for treatment outcome following neoadjuvant adriamycin/docetaxel (AT) chemotherapy in locally advanced breast cancer patients. Materials and methods: This study was a phase II study on AT neoadjuvant chemotherapy in locally advanced breast cancer patients. Patients received 50 mg/m² of doxorubicin intravenously (IV) over 15 min followed by docetaxel 75 mg/m² infused over 1 h, repeated every 3 weeks for three cycles. Surgery was performed within 3-4 weeks following the last cycle of chemotherapy. We analyzed the pre-treatment and post-treatment expression levels of ER, PgR, HER-2, Ki-67 proliferation index, and p53 and examined the correlation between the markers and clinical parameters with treatment response, overall survival and relapse-free survival following neoadjuvant treatment. Results: From July 2001 to September 2004, 61 patients were enrolled. The meaningful parameters adversely influencing survival were post-treatment ER(-) status (P = 0.013) and post-treatment Ki-67 index above 1.0% (P = 0.013). At the multivariate level, the post-treatment Ki-67 proliferation index ≤ 1.0 was the only meaningful prognostic factor for better survival (P = 0.033). Notably, tumors with Ki-67 index ≤ 1.0 were more likely to express ER with statistical significance (P = 0.002). Tumors with ER(+) and Ki-67 index ≤ 1.0 showed the highest survival rate, followed by ER(+) and Ki-67 index > 1.0%, ER(-) and Ki-67 ≤ 1.0%, and ER(-) and Ki-67 > 1.0% with the worst survival (P = 0.033). Conclusion: Collectively, post-treatment ER status and Ki-67 proliferation index were prognostic of overall survival following neoadjuvant AT chemotherapy.