Abstract P3-07-12: Correlation between clinicopathological characteristics and oncotype Dx recurrence score (RS) in early breast cancer. Experience in a Mexican population
Authors: Amador-García Geovani , Rodriguez-Meléndez Elina Alexandra , Martínez-Herrera José Fabián , Andrade-Moreno Raúl Alejandro , Reyes-Sánchez Eduardo , Vázquez-Juárez Daniela , López-Zepeda Lorena , Padilla-Rodríguez Álvaro , Olivares-Beltrán Guillermo Manuel , Villalobos-Prieto Alberto , Aguayo-González Álvaro , Pérez-Zincer Fernando , Camacho-Limas Christian Patricio , Lázaro-León José Miguel , Serrano-Olvera Juan Alberto , Gerson-Cwilich Raquel 
Published: March 2020

Introduction: Breast cancer represents the most frequently neoplasm diagnosed in women. Early breast cancer (EBC) occurs in 36-50% of cases, with recurrence rates of more than 20% at 10 years in our country. Adjuvant chemotherapy reduces recurrence rates in high-risk patients. Oncotype Dx® values ​​the expression of 21 genes associated with recurrence. This study describes the characteristics of a third-level center population and its association with the risk of recurrence over a period of 10 years.

Methods: A retrospective review of medical records of patients with early stage IA-IIB, hormone receptors (HR +) and HER2- breast cancer treated in our institution from January 2008 to December 2018 was conducted. Clinicopathological characteristics and Oncotype Dx® recurrence score (RS) were collected and a descriptive statistical analysis of the general variables was performed.

Results: We included 136 patients with EBA clinical stage (IA-IIB), HR +/ HER2-, N0-1. Median age at diagnosis was 55.03 years (30-80), the most frequent histology in the general population was invasive ductal carcinoma (88.23%), 68.38% presented in stage IA. Patients were classified into recurrence risks according to the original description of the 21-gen expression test, 72 patients (53%) were classified as low risk (LR), 49 patients (36%) at intermediate risk (IR) and 15 (11%) patients at high risk (HR) of recurrence.

For LR patients, mean age at diagnosis was 55.5 years (30-80), for HR patients the mean age was 51.9 years (32-79). Estrogen receptors (ER) were present in all patients. Progesterone receptors were positive in 97.2% of patients with LR and only in 69% in HR. 32% of LR patients expressed Ki-67 levels greater than 15% compared to HR (80%). Lymph node status was positive in 11.1% of LR patients, 30.6% for IR and 20% for RH, tumor size was &gt;20mm (T2) in 18% of LR patients and 26.6% in the HR group. Lymphovascular invasion (LVI) was present in 25% of LR patients while for HR it was positive in 60%, similar findings were found for perineural invasion (PNI) with 20.8% present in LR and 33.3% in the HR group. Nuclear grade was higher in the HR group (20% grade 3) compared to that of LR (5.5%).

When reclassifying the risk categories using the cut-off values ​​in TAILORx trial, the population distribution was modified, with a notable increase in the population in IR with 86 (63.2%) patients in this group, 28 patients in the LR group (20.5%) and 22 patients (16.1%) in HR.

Conclusions: We reported the clinicopathological characteristics of a Mexican population and its distribution according to Oncotype Dx® risk groups. A higher rate of proliferation was observed by Ki-67 in the HR group, as well as a lower age of presentation, higher rates of LVI and PNI, and a higher nuclear grade. This findings agree with those reported in the literature. The update in the cut-off values ​​for the risk categories in TAILORx resulted in an increase in the proportion of patients at intermediate and high risk.

Citation Format: Geovani Amador-García, Elina Alexandra Rodriguez-Meléndez, José Fabián Martínez-Herrera, Raúl Alejandro Andrade-Moreno, Eduardo Reyes-Sánchez, Daniela Vázquez-Juárez, Lorena López-Zepeda, Álvaro Padilla-Rodríguez, Guillermo Manuel Olivares-Beltrán, Alberto Villalobos-Prieto, Álvaro Aguayo-González, Fernando Pérez-Zincer, Christian Patricio Camacho-Limas, José Miguel Lázaro-León, Juan Alberto Serrano-Olvera, Raquel Gerson-Cwilich. Correlation between clinicopathological characteristics and oncotype Dx recurrence score (RS) in early breast cancer. Experience in a Mexican population [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 P3-07-12.