Methods for selection of neoadjuvant treatment with chemotherapy for patients with hormone receptor-positive and HER2-negative with early breast cancer.

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e12591 Background: Neoadjuvant chemotherapy (NCT) in hormone receptor positive and HER2 negative early breast cancer used to achieve a poor pathological response although patients with residual tumor inferior to 10 mm had a better significant survival. Methods: We analyzed the pathologic response (complete or major response if the residual tumor is inferior to 10 mm) in a consecutive series of 333 patients treated in our center considering clinicopathological classical variables, oncotype RS score, and non-response to previous sort course of hormonotherapy measured by the decrease in the Ki67 index. Results: Median age was of 51 years (24-87), median tumor size of 32mm (9-10) and 54% had nodal involvement. Pathologic complete response (pCR) was achieved in 16,5% and pathologic response according Symmans method type 0 and I in 33,6 %. Variables associated with pCR were initial tumor size < 30 mm (OR: 0,409; p: 0,004), progesterone receptor < 100 by histoscore (OR: 0,289; p: 0,00001) and Ki67 index > 30 (OR: 2,23; p: 0,008). When these 3 variables have been associated, the pCR increases by 45%. When use the ONCOTYPE RS score to select patients to NCT the pCR found was 23,5% that increases to 42% if the RS score was superior to 32 in a series of 136 patients. Considering the RCB pathologic response, RS>32 achieved a total of 73% of RCB 0-1 response. Finally, using the hormone non-response in patients with short course of hormonotherapy with non-decreases the Ki67 index, we found a 30% of pCR and 63% of RCB type 0-1 pathologic response. Conclusions: Selecting patients with early breast cancer with positive hormone receptors for neoadjuvant treatment with chemotherapy achieves a high response rate, going from 16% and reaching 40% in selected cases. The genomic platform and hormonal testing through Ki67 changes are very useful tools to select these patients. [Table: see text]