Abstract P6-08-55: High triple-negative breast cancer prevalence and poor outcome of hormone receptor positive breast cancer among young Mexican women

Abstract

Abstract Background: Breast cancer (BC) among young women is an emerging public health issue in Mexico, as the proportion of incident cases and deaths has been reported to be greater in women aged <40 years compared to high-income regions. However, there is scarce information in Hispanic populations regarding the presentation and outcome of this subgroup of patients. The purpose of our study was to compare the distribution of BC subtypes between age subgroups and to determine the prognostic significance of young age stratified by molecular subtype based on ER, PR, and HER2 status. Methods: This study included all consecutive patients with BC diagnosed at the National Cancer Institute in Mexico in the year 2007. A panel of ER, PR, and HER2 was used as a means of classifying BC into three molecular subtypes: (a) Hormone-receptor (HR) positive and HER2-negative, (b) Triple-negative, and (c) HER2-positive. The Chi-square test was used to compare the distribution of baseline characteristics among groups according to age (≤40 years vs. >40 years). Cox proportional hazard analysis was applied to assess the association of clinical and pathological factors with recurrence free survival with follow-up through 2013. Results: Of the 696 analyzed patients, 134 (19.3%) were ≤40 years. For the whole group, locally advanced BC accounted for the majority of the cases (61%), and there was no difference regarding clinical stage of presentation between age subgroups. The BC subtype distribution differed among age subgroups (HR-pos/HER2-neg: 42% vs. 52%, triple-negative: 30% vs. 21%, HER2-pos: 24% vs. 23%, for young vs. non-young respectively). After a median follow-up of 74.6 months, 48% of young patients experienced a recurrence compared to 39% of women >40 years. After subtype and clinical stage stratification, young age remained a significant independent predictor of recurrence in patients with HR-pos/HER2-neg tumors (hazard ratio 1.71; 95% CI:1.09-2.69; P = 0.019), but was not found to be a predictor of recurrence for patients with HER2-pos and triple negative subtypes. Conclusions: The results of our present study suggest that the poor survival associated with young age is not only driven by a high proportion of triple-negative BC, but also by poor prognosis in the most prevalent HR-pos/HER2-neg subgroups. Possible explanations for this finding are a greater proportion of Luminal B BC subtype and/or tamoxifen resistance in the young age group. Further characterization of HR-pos BC should be pursued and aggressive therapeutic strategies must be considered for treatment of young women with high-risk features. It is critical to note the extremely high prevalence of BC among young women in our Institution, which comprised 19% of the total population. To address this unmet, growing burden, we adopt the model of a specialized program for the care of young women with BC, the first in Latin America, at the National Cancer Institute in Mexico. The goals of our program include optimizing complex clinical care and supporting needs for young women and their families; promoting medical, biomedical, and social research; and educating women and health professionals to promote early cancer detection and improved multidisciplinary management. Citation Format: Cynthia Villarreal-Garza, Nancy Reynoso-Noveron, Claudia Arce-Salinas, Fernando Lara-Medina, Enrique Bargallo, Leticia Mendoza-Galindo, Federico Lasa, Maria Teresa Ramirez, Alejandro Mohar. High triple-negative breast cancer prevalence and poor outcome of hormone receptor positive breast cancer among young Mexican women [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P6-08-55.