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Journal of Oncology
Volume 2019, Article ID 1947215, 5 pages
https://doi.org/10.1155/2019/1947215
Research Article

Association of ESR1 Mutations and Visceral Metastasis in Patients with Estrogen Receptor-Positive Advanced Breast Cancer from Brazil

1PPG Ciências Médicas, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil
2Centro de Pesquisa da Serra Gaúcha (CEPESG), Caxias do Sul, Brazil
3Latin American Cooperative Oncology Group (LACOG), Porto Alegre, Brazil
4Grupo Diagnose Patologia, Genética e Biologia Molecular, Caxias do Sul, Brazil
5FARO STAT Solutions, Porto Alegre, Brazil
6Instituto Nacional do Câncer (INCA), Rio de Janeiro, Brazil
7Clínica São Vicente, Rio de Janeiro, Brazil

Correspondence should be addressed to Tomás Reinert; moc.liamtoh@treniersamot

Received 15 April 2019; Accepted 2 June 2019; Published 14 August 2019

Guest Editor: Chia-Jung Li

Copyright © 2019 Tomás Reinert et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Mutations in the ESR1 gene (ESR1m) are important mechanisms of resistance to endocrine therapy in estrogen receptor-positive advanced breast cancer and have been recognized as a prognostic and predictive biomarker as well as a potential therapeutic target. However, the prevalence of ESR1m in real-world patients has not been adequately described. Therefore, we sought to evaluate the prevalence of ESR1m in metastatic samples from Brazilian patients with estrogen receptor-positive (ER+) advanced breast cancer previously treated with endocrine therapy. The presence of ESR1m was evaluated in formalin-fixed paraffin-embedded (FFPE) breast cancer tissue using real-time quantitative polymerase chain reaction (RT-qPCR). Mutations in codons 380, 537, and 538 of the ESR1 gene were analyzed. Out of 77 breast cancer samples, 11 (14.3%) showed mutations in the ESR1 gene. ESR1m were detected in a variety of organs, and the D538G substitution was the most common mutation. In visceral metastasis, ESR1m were detected in 25% (8/32) of the samples, whereas in nonvisceral metastasis, ESR1m were detected in 6.7% (3/45) of the samples. The odds of a sample with visceral metastasis having an ESR1 mutation is 4.66 times the odds of a sample of nonvisceral metastasis having an ESR1 mutation (95% CI: 1.13–19.27; value = 0.0333). Our study indicates that the prevalence of ESR1m in samples from Brazilian patients with metastatic ER+ breast cancer is similar to that described in patients included in clinical trials. We observed an association of ESR1m with visceral metastasis.