Abstract P4-05-15: Follow-up of prospective cohort of Mexican premenopausal women with breast cancer who received guided adjuvant treatment with the EndoPredict assay
Authors: Vazquez-Juarez Daniela , Vaca-Cartagena Bryan F , Becerril-Gaitan Andrea , Deneken-Hernandez Zuratzi , Ferrigno Ana S , Maffuz-Aziz Antonio , Lopez-Martinez Edna A , Barragan-Carrillo Regina , Muñoz-Lozano Jose F , Villarreal-Garza Cynthia 
Published: March 2022

Background: Choosing the appropriate treatment for patients with early hormone receptor (HR)-positive and HER2-negative breast cancer (BC) remains a challenging process that must balance possible therapy benefits against potential side effects. Recent reports on premenopausal patients raise concerns about the safety of omitting chemotherapy (CT), and no consensus has been reached to define the use of these tools in the decision-making process. Thus, further research is needed to guide the use of genomic testing on this young group. Due to the limited data of the EndoPredict (EP) assay performance in premenopausal women, we aim to describe the follow-up results of a prospective cohort that utilized the EP assay to guide adjuvant treatment decision-making in this group of patients. Methods: Premenopausal women with HR-positive, HER2 negative, T1-T2, and N0-N1 BC who received adjuvant treatment guided by the results of the EP assay in two referral BC centers in Mexico were included. Clinicopathological and genomic characteristics were collected. Recurrence-free survival (RFS) and distant disease-free survival (DDFS) were evaluated using the Kaplan-Meier estimate. The Chi-squared and Log-rank tests were employed for group comparisons. Results: A total of 99 patients with a median age at diagnosis of 43 years (IQR 39-46) were analyzed. Most patients had T2 (54%), node-negative disease (72%), and low/intermediate-grade disease (85%). The distribution of clinical stages at diagnosis was: IA (38%), IB (2%), IIA (37%), IIB (22%). Regarding EPclin scores, 54% patients were categorized as high-risk while 47% had low-risk of distant recurrence. With respect to CT, 15% of patients in the low-risk group received CT compared to 100% in the high-risk category (p&lt;0.001). Only 9% of patients received hormone therapy (HT) along with ovarian suppression mainly due to financial restrictions. Median follow-up for the entire cohort was 39 months (IQR 33-50). In total, 7 patients experienced disease recurrence: 3 in the low-risk and 4 in high-risk EPclin groups; data are shown in the table. Of the recurrences, 4 (57%) were local/regional and 3 (43%) were distant. Of note, all 3 recurrences experienced by patients assigned to a low-risk category were local/regional. Remarkably, all patients with recurrent disease received HT only with tamoxifen. Regarding sites of distant metastasis, 1 was visceral, 1 was non-visceral, and the other was mixed (visceral and non-visceral). At 48 months, patients with low-risk and high-risk EP had a RFS of 89.8% (95CI 78.04%-100%) and 92.1% (83.08-100%), respectively. Regarding DDFS, at 48 months the low-risk EP group had no events recorded, while DDFS for the high-risk group was 94.2% (95%CI 85.97-100%), (p=0.094). One patient in the high-risk group has died up to this follow-up. Conclusion: In this cohort, the use of EP as a guidance for treatment decision-making proved to be an effective tool as patients with low-risk EP in whom CT was omitted did not have an increased risk of distant recurrence. Moreover, patients with high-risk EP scores had a not significant worse DDFS compared with those with low-risk EP, possibly accounting for patients not receiving the most optimal HT. A longer follow-up is required to monitor recurrence events and survival. Further studies are warranted for assessing EP and other genomic signatures’ impact in CT de-escalation and survival among premenopausal women.

Clinicopathological characteristics of patients with recurrent disease.Age (y) at diagnosisStage (pT pN)GradeER (%)PR (%)Ki67 (%)EP resultEPclin scoreCTHTType of recurrence37IIA (T2 N0)29595N/ILow risk2.7NoTamoxifenLocal/regional43IA (T1c N0)2802010Low risk2.9NoTamoxifenLocal/regional45IA (T1c N0)21006020Low risk3.2NoTamoxifenLocal/regional42IIA (T2 N0)N/I1007040High risk3.9YesTamoxifenLocal/regional38IIA (T2 N0)2704040High risk4.2YesTamoxifenDistant35IIB (T2 N1)2604010High risk4.4YesTamoxifenDistant41IIB (T2 N1)2909070High risk5.1YesTamoxifen (after CT-induced ovarian failure)DistantER= Estrogen receptor status. PR= Progesteron receptor status. N/I= No information.

Citation Format: Daniela Vazquez-Juarez, Bryan F Vaca-Cartagena, Andrea Becerril-Gaitan, Zuratzi Deneken-Hernandez, Ana S Ferrigno, Antonio Maffuz-Aziz, Edna A Lopez-Martinez, Regina Barragan-Carrillo, Jose F Muñoz-Lozano, Cynthia Villarreal-Garza. Follow-up of prospective cohort of Mexican premenopausal women with breast cancer who received guided adjuvant treatment with the EndoPredict assay [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P4-05-15.