Breast density and the risk of breast cancer

Abstract

Introduction: Breast cancer is the type of cancer that mostly affects women worldwide, both in developing and developed countries. It is the world's leading cause of cancer death in women, with an estimated 520,000 deaths per year. Excluding non-melanoma skin cancer, breast cancer accounts for 28.1% of all cases of cancer in women. To date, mammographic screening is advocated worldwide as a method of secondary prevention and early diagnosis of breast cancer. However, it is negatively influenced by breast density (BD), considering that there is a reduction in the sensitivity of the method as breast density increases. There may be a loss of up to 30-40% of the sensitivity of mammography in cases of dense breasts. It should also be noted that BD is currently considered an independent risk factor for breast cancer. Studies have shown an increased risk of up to 4 to 6 times in cases of dense breasts. Although it is not yet clear which mechanism is involved for this increased risk, it is believed to be related to the increased volume of fibroglandular tissue and, thus, to the increased number of epithelial cells subject to carcinogenesis and cancer development. In addition, some recent studies have evaluated the possible correlation between BD and tumor aggressiveness, showing a certain association between denser breasts and high grade and less differentiated tumors. Objective: to evaluate the relationship between breast density and the development of breast cancer and its subtypes in Brazilian women. Methods: this is a clinical analytical and retrospective trial for the evaluation of breast density and breast cancer. The population group will be composed of patients who underwent mammography at the Clinic Hospital of Botucatu-Unesp from 2014 to 2018 and had the breast density standard classified according to the fifth edition of the BIRADS (Breast Imaging Reporting and Data System) by the team of Center for Evaluation in Breast Diseases of the Faculty of Medicine of Botucatu - Department of Gynecology, Obstetrics and Breast Diseases of the Botucatu Medical School - UNESP. The sample will be non-probabilistic and by adhesion. Exclusion criteria will be: BIRADS mammography 4 or 5 with no biopsy result and patient with BIRADS 0 mammography without further investigation until data collection. The main variables of breast density related to breast cancer will be verified. The observed results will be annotated in specific protocols and stored in database developed in spreadsheet of Microsoft Excel for Windows software properly adapted for statistical analysis. From the data, tables with the results will be performed. Statistical tests will be bilateral and the level of significance adopted will be 5%. The analyzes will be done using the Statistical Analyzes System (SAS) for Windows, version 9.2, by the Research Support Office (EAP) of the Botucatu Medical School, that will conduct the analysis procedures. Expected results the project is expected to show that there is a relationship between breast density and breast cancer, associating dense breasts with an increased risk of breast cancer, as well as increased risk of aggressive tumors. Thus, with a significant repercussion on the characterization and consequent greater attention of patients with dense breasts.