Abstract P2-16-20: Treatment outcomes in triple negative breast cancer patients undergoing neoadjuvant chemotherapy. The importance of Ki-67

Abstract

Abstract Aim of study: The aim of this retrospective project is to evaluate the treatment outcomes including pathological complete response (pCR), time to progression and overall survival in patients (pts) treated with taxane, and/or anthracycline/alkylating agents based neoadjuvant chemotherapy (NAC). Background: Ki-67 immunohistochemical determination is a widely used biomarker of cell proliferation in pts undergoing endocrine treatment for breast cancer. The role of Ki-67 in triple negative breast cancer (TNBC) pts undergoing NAC for early disease remains controversial. Pathological Complete Response following NAC has been proposed as a prognostic indicator of long-term outcome. Methods: We analyzed retrospectively data on 86 pts with TNBC. Pathological complete response (pCR) was defined as the complete disappearance of the invasive cancer in the breast and absence of tumor in the axillary lymph nodes examined by axillary clearance. The purpose of this analysis was to investigate factors associated with combined pCR. Results: There were 35 pCR’s (40.7%). At 2 years 82% of pts who attained a pCR were disease free compared to 67% of pts who did not attain a pCR (log rank test p < 0.0117). On univariate analysis factors associated with higher combined pCR included primary tumor size (T1=84% vs T2 and T3 =50% of pts, chi2= 6.81, p<0.03317), Ki67 (>30=68% vs. eq or < 30%= 18% of pts, p<0.00020), age (< than 50 =71% vs. equal or >50 =44% of pts), tumor grade (1=88% vs. 2=60% vs. 3=44% of pts, chi2 = 6.2560 p<0.04381) and stage (I= 89% vs. IIA=60% vs. IIB=46% vs. III=40% of pts, p<0.01350). Factors not associated with a higher pCR included menopausal status, extranodal spread and lympho-vascular invasion. In a logistic regression model Ki-67 as a continuous variable (p<0.012577) and age < than 50 (p<0.03318) retained its significance; while tumor size, stage of disease, tumor grade loss significance. Conclusion: Ki67 and age are independent prognostic factors of pCR in pts with early TNBC undergoing NAC. Citation Format: Bernardo Leon Rapoport, Jacqui Barnard-Tidy, Ronwyn van Eeden, Teresa Smit, Simon Nayler, Carol Benn. Treatment outcomes in triple negative breast cancer patients undergoing neoadjuvant chemotherapy. The importance of Ki-67 [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P2-16-20.