Evaluation of the HER2 positivity rate and the influence of three types of breast biopsy in immunohistochemistry result in women with invasive breast cancer at the Brasília’s University Hospital

Abstract

Purpose: To assess the rate of HER2 positivity in patients with breast cancer at Brasília’s University Hospital (HUB) and to verify if the type of biopsy influences the outcome of immunohistochemistry Methods: Observational, retrospective and descriptive study. The data were collected from patients treated from January 2009 to December 2010 and the selection criteria were: female patients with invasive breast cancer and with histopathological diagnosis carried out at HUB. A spreadsheet was made with the results of HER2 immunohistochemistry and the type of biopsy realized. Data were analyzed by χ2 difference test. Results: The study included 134 patients. In this sample, it was observed 13.43% of HER2 positivity frequency, 82.84% of negative and 3.73% was inconclusive (2+). Biopsy done by core biopsy had a tendency to positivity (1.32 deviation), by sector to negativity (-2.29 deviation) and lumpectomy was indifferent (0.97 deviation). Conclusions: Based on this result, the best type of biopsy to perform immunohistochemistry is a core biopsy. The rate of HER2 positivity is below the literature. Therefore, we suggest that the material sent for immunohistochemistry should be carefully prepared from the collection. Thus, very probably, results will be obtained, with tumors that overexpress HER2, closer to the literature.