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Purpose: RACGAP1 is a Rac GTPase-activating protein involved in cell growth regulation, cell transformation and metastasis. The aim of the present study was to explore the prognostic and/or predictive significance of RACGAP1 mRNA expression on disease-free survival (DFS) and overall survival (OS) in high-risk early breast cancer patients and compare it to that of Ki67 protein expression and to the Nottingham prognostic index (NPI)., Methods: A total of 595 high-risk breast cancer patients were treated in a two-arm trial evaluating postoperative dose-dense sequential chemotherapy with epirubicin followed by CMF with or without paclitaxel. RNA was extracted from 314 formalin-fixed paraffin-embedded primary tumor tissue samples followed by one-step quantitative RT-PCR for assessing RACGAP1 mRNA expression., Results: High RACGAP1 mRNA expression (above the median) was associated with poor DFS (log-rank, p = 0.002) and OS (p < 0.001). High histological grade, as well as high Ki67 protein expression, was more frequent in the high-expression group of RACGAP1. Results of the Cox multivariate regression analysis revealed that high RACGAP1 mRNA expression independently predicted poor overall survival (Wald's p = 0.008). High Ki67 protein expression was also an adverse prognostic factor for death (p = 0.016), while high NPI score values were not., Conclusions: High RACGAP1 mRNA expression, as assessed by qRT-PCR, was found to be of adverse prognostic significance in high-risk early breast cancer patients treated with dose-dense sequential chemotherapy. The utility of RACGAP1 mRNA expression in patient selection for treatment with aggressive chemotherapy regimens should be further explored and validated in larger cohorts.

Purpose: It is well recognized that breast cancer is a heterogeneous disease. The purpose of the current study was to classify patients according to the immunohistochemical phenotype of their tumors in an effort to evaluate the outcome of the respective groups of patients and specifically of those with triple-negative breast cancer (TNBC) following dose-dense sequential adjuvant chemotherapy., Methods: A total of 595 patients with high-risk breast cancer were treated with adjuvant anthracycline-based dose-dense sequential chemotherapy with or without paclitaxel in the context of a randomized study. ER, PgR, HER2, Ki67, EGFR, and CK5 protein expression were evaluated in 298 formalin-fixed paraffin-embedded tumor samples by immunohistochemistry (IHC). HER2 was also evaluated by chromogen in situ hybridization (CISH). HER2 status and Ki67 protein expression differentiated luminal IHC subtypes (luminal B tumors being HER2 and/or Ki67-positive)., Results: Among the 298 tumors, the immunohistochemical panel classified 37 (12%) as luminal A, 198 (66%) as luminal B, 27 (9%) as HER2 enriched, and 36 (12%) as TNBC. The median follow-up time was 97 months. Patients with luminal A tumors had the best prognosis, with improved disease-free survival (log-rank, P = 0.033) and overall survival (P = 0.006) compared with the other three tumor subtypes. The three subtypes had an increased risk for relapse and death compared with luminal A in multivariate analysis, as well. No benefit from paclitaxel treatment was detected in any of the four subtypes or the total cohort. Hierarchical clustering based on mRNA expression of ER, PgR, and HER2 by quantitative RT-PCR identified patient groups that were comparable to the subtypes identified by IHC., Conclusions: The results of this study confirm that triple negative, luminal B and HER2-enriched phenotypes identified by IHC are of adverse prognostic value in high-risk breast cancer patients treated with dose-dense sequential adjuvant chemotherapy.