BRCA mutations in triple negative breast cancer patients in Guatemala: A descriptive study.

Abstract

e22543 Background: In Guatemala, breast cancer is the most common malignancy among women, the habitants in the country are characterized by being of different ethnic groups and little is understood about the prevalence of germline mutations and their influence in the prognosis and diagnosis of triple negative breast cancer patients, reason why the aim of our study is to determine the prevalence of BRCA1 and BRCA2 germline mutations among this population. Methods: Forty-five patients with confirmed biopsy of triple negative breast cancer by immunohistochemistry treated at Liga Nacional Contra el Cáncer-INCAN Guatemala in 2022 were enrolled in the study. Triple negativity was defined as < 1% estrogen, progesterone and HER2 staining by immunohistochemistry or not amplified by fluorescence in situ hybridization in those with HER2 borderline result. After consent, patients had next generation sequencing and multiplex ligation-dependent probe amplification for BRCA1 and BRCA2 genes. From medical records, we obtained: demographic, clinico-pathological and treatment data. Median was calculated for age, while frequencies and percentages were computed for the categorical variables. Results: The study identified 19 patients with a BRCA1 or BRCA2 germline mutations (42.22%). The median age at cancer diagnosis was 39 vs. 49 years old compared to patients with lack of mutations of the genes analyzed. The majority harboring a mutation (36.84%) were from the countryside, especially the regions IV and V (southeast and central). Among all groups, (66.67%) were diagnosed with locally advanced disease and initially treated with neoadjuvant chemotherapy. According to our findings, the most prevalent mutations were located in the BRCA1 gene (47.37%), with BRCA1 c.212+1G > A and BRCA2 c.2806_2809del being the most frequent variants (36.84%). Conclusions: Triple negative breast cancer patients in Guatemala have higher prevalence of BRCA1 and BRCA2 mutations than reported among other populations, longer follow up of this study is expected to confirm the results and further understand how the presence of mutations could affect the response to treatment of the patients, their prognosis and the impact in their families. [Table: see text]