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Objectives, to stablish the frequency of BRCA1/2 mutation rate in high-penetrance breast cancer susceptibility population Methods Based on NCCN guidelines for testing criteria for high-penetrance breast cancer susceptibility genes genetic counseling was offered to 140 breast cancer patients in the hemato-oncology unit of Roosevelt Hospital at Guatemala City performing test with NGS and MLPA technology from 2019 to 2021. Results The overall BRCA1/2 mutation rate high-risk patients were 23% (33/140). Of the patients with mutations, 66.6% (22/33) had BRCA1 mutation, 33.3% (11/33) had BRCA2 mutation, of the mutated population the median age was 45 years. Regarding the phenotype in the mutated population, 75% were triple negative, 16% luminal and 9% with Her2 overexpression. Of the patients carrying the BRCA1 mutation, we identified the c.212+1G>A mutation in 40% of the patients, possibly a founder mutation. In the triple negative population and under 45 years of age, the percentage of patients with BRCA 1/2 mutation is 40.9 (88.8% BRCA1 and 11.1% BRCA2). Conclusions: we found a percentage of BRCA 1/2 mutations in the selected population (NCCN criteria) similar to that reported in other Latin American countries, highlighting the high percentage of BRCA mutations in women under 45 years with triple negative phenotype, previous reports have highlighted the frequency of the c.212+1G>A mutation of BRCA1 in breats cancer patient in Guatemala, in this study 40% of the BRCA1 mutations correspond to said mutation, considering it as a probable founder mutation. Citation Format: Juan Alvarado-Muñoz, Agatha Reyes-Morales, Marco Chivalan, Silvana Torselli, Hector Valenzuela, Gozalo Yalibat, Mario Ordoñez, Rosa León, Egly Alvarez. BRCA1/2 gene mutations in patients with high-risk breast cancer in a tertiary-level hospital in Guatemala [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P5-03-17.

Background: Breast cancer is the frequent neoplasia in young women, which in developing countries is associated with more adverse outcomes. In Latin America, reports have shown an increased incidence of breast cancer in young women. No information exist regarding breast cancer characteristics in young Guatemalan women. We aimed to describe the clinical-pathological features among women aged 45 years or less treated in a tertiary-level hospital in Guatemala. Methods: We examined data from 119 women aged 45 years or less diagnosed with primary invasive breast cancer at the Oncology Unit Roosevelt Hospital in Guatemala between 2016 and 2020. Data were drawn from medical files on sociodemographic characteristics, histology, clinical stage, and breast cancer subtypes.Results: Of the total sample, breast cancer in women aged 45 years or less represented 31.2% of the cases. Of these, 24.36% is before 35 years, 28.57% between 35 to 39 years, and 47.05% between 39 to 45 years. Advanced clinical stages affected 66.6% of young women (48.33% for stages III and 18.33% stage IV). Data from specific breast cancer molecular subtype showed that 72.35% of cases in young women expressed an aggressive molecular subtype (Her-2 positive 27.06%, triple-negative 21.76%, and luminal/Her-2 positive 23.53%). Regarding treatment, most young patients received surgical treatment, as well as neoadjuvant or adjuvant chemotherapy. Only 24.37% received hormonal and 26.89% radiation therapy. Conclusions: Our finding suggested that young women treated for breast cancer at a tertiary-level hospital in Guatemala had a high proportion of aggressive molecular subtypes and a high rate of locally advanced disease. This aggressive cancer behavior among young women is consistent with findings in other Latin American countries. Evidence examining risk factors for aggressive cancer in young women, such as delay in diagnosis and treatment timing, is warranted. Table 1. Distributions of socio-demographic and cancer-related characteristics variables% (SE)n = 119ETHNIC GROUPMayan Indigenous12.61 (3.05)No-Mayan Indigenous87.39 (3.05)HISTOLOGYDuctal96.64 (1.66)Lobular1.68 (1.18)Other1.68 (1.18)CLINICAL STAGE*I1.67 (1.17)II31.67 (4.26)III48.33 (4.58)IV18.33 (3.54)BREAST CANCER SUBTYPELuminal27.65 (4.76)Her2 positive27.06 (5.11)Triple-negative21.76 (5.05)Luminal/Her223.53 (6.61)TREATMENTSurgery55.46 (4.58)Neoadjuvant Chemotherapy82.35 (3.51)Adjuvant Chemotherapy47.06 (4.59)Radiotherapy26.89 (4.08)Hormonotherapy24.37 (3.95) Citation Format: Juan F Alvarado-Muñoz, Agatha Reyes-Morales, Alba J Kihn-Alarcón, Marco Chivalan, Silvana Torselli, Victor Puac-Polanco. Breast cancer in young women in a tertiary-level hospital in Guatemala [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS7-64.

Background. Triple-negative (TNBC) is the most aggressive subtype of breast cancer and represents 12% of all cases in the US. In the Mexican population, the prevalence of TNBC is 23%. The prognosis is poor for most of these women, with a higher risk of locoregional recurrence, lower disease-free survival, and lower cancer-specific survival. The sociodemographic characteristics of Central American women, such as indigenous, afro descendants, and Hispanic descent, have been associated with factors such as high nuclear grade, high proliferation index, aggressive clinical presentation with advanced stages, high recurrence rates, and an increased risk of cancer fatality rate. Yet, no epidemiological characterization of women treated for TNBC in specialized hospitals in Central American countries exists to this date. Therefore, we describe the characteristics of women diagnosed with TNBC in three specialized hospitals in Guatemala and Honduras. Methods. We identify 1,501 women with breast cancer who attended three specialized hospitals, two in Guatemala and one in Honduras, from 2015 to 2021. Self-reported sociodemographic and clinical characteristics were determined, as well as pathologic data from medical records. Results. Of the 1,501 women, 272 (18.12%) were diagnosed with triple-negative phenotype. The median age was 49.5 years, with 25% under 40.5 years of age, 95.2% reported mestizo race, 51.5% were pre-menopausal, 49.6% had a high histologic grade (grade 3), and 98.8 had locally advanced disease (Table 1). Conclusions: The characteristics described in our sample were similar to those in other Hispanic populations. The prevalence of TNBC in our sample was lower than in Mexico but higher than that of the US. Our sample was made of primarily young women with locally advanced disease and pathologic factors associated with aggressive cancer behavior, such as high grade, lymphovascular invasion, and high Ki67 index. This first report is the product of a multidisciplinary team with interest in breast cancer subtypes. Our objectives include expanding the collaboration of clinical researchers to all the Central American and Caribbean countries and contributing to the understanding of molecular behavior of TNBC and support advances in treatment. Table 1.Characterization of women diagnosed with TNBC in three hospitals in Central AmericanCHARACTERISTIC% (95% CI)n = 272RaceMestizo95.2 (91.9 - 97.2)Indigenous4.8 (2.8 - 8.1)AgeMean (SD)49.5 years (11.7)IQR40.5 - 57Tobacco useYes3.7 (2.0 – 6.7)Number of pregnanciesMean (SD)1.5 (0.5)IQR1 – 2MenopauseYes48.5 (42.6 – 54.5)Use of contraceptivesYes14.0 (10.3 – 18.7)MulticentricYes19.2 (14.9 – 24.5)HypertensionYes8.4 (5.7 – 12.4)DiabetesYes8.8 (6.0 – 12.9)IMCLess than 3042.3 (36.5 – 48.3)Family history of cancerYes12.9 (9.4 – 17.5)Histologic grade15.5 (3.3 – 9.0)244.8 (39.0 – 50.8)349.6 (43.7 – 55.6)Lymphovascular invasionYes44.5 (38.6 – 50.5)Clinical stageI1.1 (0.3 – 3.4)II40.4 (34.7 – 46.4)III54.4 (48.4 – 60.8)IV4.0 (2.2 – 7.2)KI 67Mean (SD)46.9 (24.1)IQR30 - 70TherapyNeoadjuvant chemotherapy29.2 (21.3 – 38.7)RPC32.1 (23.9 – 41.6)Surgery97.4 (94.5 – 98.7)Adjuvant chemotherapy55.0 (49.0 – 60.8)Radiotherapy94.4 (90.8 – 96.6)MetastasisYes4.0 (2.2 – 7.2)BRCAMutated0.4 (0.0 – 2.6)WT2.2 (1.0 – 4.8) Citation Format: Agatha Reyes-Morales, Juan Francisco Alvarado-Muñoz, Suyapa Bejarano, Hugo Castro, Victor Puac-Polanco, Marco Chivalan, Silvana Torselli. Characterization of triple-negative breast cancer in two Central American countries [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 P3-12-23.