Abstract P2-08-54: Change in therapeutic management after EndoPredict assay in a prospective decision impact study of Mexican premenopausal patients
Authors: Villarreal-Garza C , Deneken-Hernandez Z , Maffuz-Aziz A , Lopez-Martinez EA , Muñoz-Lozano JF , Barragan-Carrillo R , Peña-Curiel O , Moreno B , Ramos-Elias P , Diaz H , Bautista-Piña V 
Published: May 2019

Background: Often, therapeutic decision-making in breast cancer (BC) patients is deeply influenced by age, with young women receiving highly aggressive systemic therapy, even when low clinical risk features are present. Currently, genomic signature studies have included a limited number of young patients, thus hindering their use in this population. Furthermore, significant data about their impact on clinical decision-making is lacking. Consequently, the medical community should strive to identify young patients who would not benefit from chemotherapy (CT). The aim of this prospective study was to determine the impact of the EndoPredict assay on adjuvant decision-making by a multidisciplinary team in premenopausal women.

Patients and method: A total of 92 premenopausal women with hormone receptor-positive, HER2 negative, T1-T2, and N0-N1 BC have been included. Clinicopathological characteristics were recorded and each case presented in a multidisciplinary tumor board. Consensual therapeutic decisions before and after EndoPredict results were registered. Pearson chi-square was used to analyze differences between groups.

Results: Median age at diagnosis was 43.5 years (y), with 68% being ≤ 45y. 28% had node-positive disease. Stage at diagnosis was: I (40%), IIA (36%), and IIB (23%). 11%, 72%, and 10% of tumors were low-, intermediate-, or high-grade, respectively.

A total of 39 patients (46%) had a low-risk EPclin result. Notably, 61% of patients in the N0 group had a low-risk result compared to 9% with N1 status (p&lt;.001). Additionally, 30% of patients ≤ 40y-old had a low-risk EPclin, compared with 53% in older patients (p=.0421). Tumor grade was significantly associated with EPclin, with 90% of low-grade tumors being low-risk, while 89% of grade 3 BC had a high-risk result (p=.0023). Grade 2 BC was not predictive of EPclin results, with 45% of patients being classified as low risk. No significant association was found between Ki67 or LVI, and EPclin.

Change in CT decision was recorded in 14/85 patients (17%), with the greatest impact in CT reduction (table 1). Furthermore, 22/85 (26%) and 19/85 (22%) had a change in CT and anti-hormonal therapy regimen, respectively. Overall therapeutic compliance with EndoPredict results was 95%: 100% of patients with a high-risk EPclin received CT, while 87% with a low-risk result did not.

Table 1.Pre- and Post-EndoPredict CT consensus  Post-TestPost-Test   No CTCTTotalPre-TestNo CT24 (28%)4 (5%)28 (33%)Pre-TestCT10 (12%)47 (55%)57 (67%) Total34 (40%)51 (60%)85 (100%)

Conclusions: This is the first study that evaluates the EndoPredict assay effect in decision-making in a premenopausal BC patient cohort. The less overall therapy change observed, compared to previous studies, could be the result of a reliable clinical judgment for identifying high-risk patients, which represent a large proportion in this young group. Overall, the test's greatest impact was aiding the discrimination of patients that would not benefit from CT, thus avoiding unnecessary adverse effects. In conclusion, the EndoPredict test successfully assisted the clinical decision-making process in premenopausal patients, with a high rate of therapeutic compliance and a significant change in overall decision.

Citation Format: Villarreal-Garza C, Deneken-Hernandez Z, Maffuz-Aziz A, Lopez-Martinez EA, Muñoz-Lozano JF, Barragan-Carrillo R, Peña-Curiel O, Moreno B, Ramos-Elias P, Diaz H, Bautista-Piña V. Change in therapeutic management after EndoPredict assay in a prospective decision impact study of Mexican premenopausal patients [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-08-54.